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1.  Prenatal Stress Exposure Related to Maternal Bereavement and Risk of Childhood Overweight 
PLoS ONE  2010;5(7):e11896.
Background
It has been suggested that prenatal stress contributes to the risk of obesity later in life. In a population–based cohort study, we examined whether prenatal stress related to maternal bereavement during pregnancy was associated with the risk of overweight in offspring during school age.
Methodology/Principal Findings
We followed 65,212 children born in Denmark from 1970–1989 who underwent health examinations from 7 to 13 years of age in public or private schools in Copenhagen. We identified 459 children as exposed to prenatal stress, defined by being born to mothers who were bereaved by death of a close family member from one year before pregnancy until birth of the child. We compared the prevalence of overweight between the exposed and the unexposed. Body mass index (BMI) values and prevalence of overweight were higher in the exposed children, but not significantly so until from 10 years of age and onwards, as compared with the unexposed children. For example, the adjusted odds ratio (OR) for overweight was 1.68 (95% confidence interval [CI] 1.08–2.61) at 12 years of age and 1.63 (95% CI 1.00–2.61) at 13 years of age. The highest ORs were observed when the death occurred in the period from 6 to 0 month before pregnancy (OR 3.31, 95% CI 1.71–6.42 at age 12, and OR 2.31, 95% CI 1.08–4.97 at age 13).
Conclusions/Significance
Our results suggest that severe pre-pregnancy stress is associated with an increased risk of overweight in the offspring in later childhood.
doi:10.1371/journal.pone.0011896
PMCID: PMC2912844  PMID: 20689593
2.  Prenatal Exposure to Bereavement and Type-2 Diabetes: A Danish Longitudinal Population Based Study 
PLoS ONE  2012;7(8):e43508.
Background
The etiology of type-2 diabetes is only partly known, and a possible role of prenatal stress in programming offspring for insulin resistance has been suggested by animal models. Previously, we found an association between prenatal stress and type-1 diabetes. Here we examine the association between prenatal exposure to maternal bereavement during preconception and pregnancy and development of type-2 diabetes in the off-spring.
Methods
We utilized data from the Danish Civil Registration System to identify singleton births in Denmark born January 1st 1979 through December 31st 2008 (N = 1,878,246), and linked them to their parents, grandparents, and siblings. We categorized children as exposed to bereavement during prenatal life if their mothers lost an elder child, husband or parent during the period from one year before conception to the child’s birth. We identified 45,302 children exposed to maternal bereavement; the remaining children were included in the unexposed cohort. The outcome of interest was diagnosis of type-2 diabetes. We estimated incidence rate ratios (IRRs) from birth using log-linear poisson regression models and used person-years as the offset variable. All models were adjusted for maternal residence, income, education, marital status, sibling order, calendar year, sex, and parents’ history of diabetes at the time of pregnancy.
Results
We found children exposed to bereavement during their prenatal life were more likely to have a type-2 diabetes diagnosis later in life (aIRR: 1.31, 1.01–1.69). These findings were most pronounced when bereavement was caused by death of an elder child (aIRR: 1.51, 0.94–2.44). Results also indicated the second trimester of pregnancy to be the most sensitive period of bereavement exposure (aIRR:2.08, 1.15–3.76).
Conclusions
Our data suggests that fetal exposure to maternal bereavement during preconception and the prenatal period may increase the risk for developing type-2 diabetes in childhood and young adulthood.
doi:10.1371/journal.pone.0043508
PMCID: PMC3429491  PMID: 22952698
3.  Antenatal maternal bereavement and childhood cancer in the offspring: a population-based cohort study in 6 million children 
British Journal of Cancer  2012;107(3):544-548.
Background:
Prenatal stress may increase the susceptibility to childhood cancer by affecting immune responses and hormonal balance. We examined whether antenatal stress following maternal bereavement increased the risk of childhood cancer.
Methods:
All children born in Denmark from 1968 to 2007 (N=2 743 560) and in Sweden from 1973 to 2006 (N=3 400 212) were included in this study. We compared cancer risks in children born to women who lost a first-degree relative (a child, spouse, a parent, or a sibling) the year before pregnancy or during pregnancy with cancer risks in children of women who did not experience such bereavement.
Results:
A total of 9795 childhood cancer cases were observed during follow-up of 68 360 707 person years. Children born to women who lost a child or a spouse, but not those who lost other relatives, had an average 30% increased risk of any cancer (hazard ratio (HR) 1.30, 95% confidence interval (CI) 0.96–1.77). The HRs were the highest for non-Hodgkin disease (512 cases in total, HR 3.40, 95% CI 1.51–7.65), hepatic cancer (125 cases in total, HR 5.51, 95% CI 1.34–22.64), and testicular cancer (86 cases in total, HR 8.52, 95% CI 2.03–37.73).
Conclusion:
Our data suggest that severe antenatal stress following maternal bereavement, especially due to loss of a child or a spouse, is associated with an increased risk of certain childhood cancers in the offspring, such as hepatic cancer and non-Hodgkin disease, but not with childhood cancer in general.
doi:10.1038/bjc.2012.288
PMCID: PMC3405225  PMID: 22759879
childhood cancer; bereavement; prenatal stress; mother; association
4.  Use of corticosteroids during pregnancy and risk of asthma in offspring: a nationwide Danish cohort study 
BMJ Open  2014;4(6):e005053.
Objective
To examine whether in utero exposure to local and systemic corticosteroids is associated with asthma development in offspring.
Design
Cohort study.
Setting
Denmark.
Participants
We included all singletons born alive in Denmark between 1996 and 2009. Data on maternal corticosteroid use, asthma in offspring and covariates were obtained from medical registries.
Main outcome measures
We compared asthma risks of children prenatally exposed to corticosteroids and of children of former corticosteroid users with that of unexposed children. We computed absolute risks and used proportional-hazards regression to compute adjusted HRs (aHRs). Using logistic regression we compared exposed children with unexposed siblings in a ‘within-mother-between-pregnancy’ analysis. Adjustment addressed varying length of follow-up.
Results
We identified 877 778 children, 3.6% of whom were prenatally exposed to systemic (n=5327) or local (n=24 436) corticosteroids. A total of 105 677 children developed asthma during follow-up with a 10-year risk of 18.4% among the exposed and 13.5% among the unexposed. The aHR was 1.54 (95% CI 1.45 to 1.65) for systemic use, 1.45 (95% CI 1.40 to 1.50) for local use and 1.32 (95% CI 1.30 to 1.34) for former use. The adjusted OR of the ‘within-mother-between-pregnancy’ analysis was 1.11 (95% CI 0.98 to 1.25).
Conclusions
These population-based data do not support a strong causal association between maternal corticosteroid use during pregnancy and increased asthma risk in offspring.
doi:10.1136/bmjopen-2014-005053
PMCID: PMC4054622  PMID: 24902733
CLINICAL PHARMACOLOGY; EPIDEMIOLOGY; PERINATOLOGY; RESPIRATORY MEDICINE (see Thoracic Medicine)
5.  Psychological Stress and Hospitalization for Childhood Asthma-a Nationwide Cohort Study in Two Nordic Countries 
PLoS ONE  2013;8(10):e78816.
Objective
Exposures to psychological stress in early life may contribute to the development or exacerbation of asthma. We undertook a cohort study based on data from several population-based registers in Denmark and Sweden to examine whether bereavement in childhood led to increased asthma hospitalization.
Methods
All singleton children born in Denmark during 1977-2008 and in Sweden during 1973-2006 were included in the study (N=5,202,576). The children were followed from birth to the date of first asthma hospitalization, emigration, death, their 18th birthday, or the end of study (31 December 2007 in Sweden and 31 December 2008 in Denmark), whichever came first. All the children were assigned to the non-bereaved group until they lost a close relative (mother, father or a sibling), from when they were included in the bereaved group. We evaluated the hazard ratio (HR) of first hospitalization for asthma in bereaved children using Cox proportional hazards regression models, compared to those who were in the non-bereaved group. We also did a sub-analysis on the association between bereavement and first asthma medication.
Results
A total of 147,829 children were hospitalized for asthma. The overall adjusted HR of asthma hospitalization in bereaved children was 1.10 (95% confidence interval (CI): 1.04-1.16), compared to non-bereaved children. The risk of asthma hospitalization was increased in those who lost a close relative at age of 14-17 years (HR=1.54, 95% CI: 1.23-1.92), but not in younger age groups. The association between bereavement and asthma hospitalization did not change over time since bereavement. In the sub-analysis in singleton live births during 1996-2008 recorded in the DMBR, bereavement was associated with a lower use of asthma medication (HR=0.87, 95% CI: 0.80-0.95).
Conclusions
Our data suggests that psychological stress following bereavement in late adolescence is associated with an increased risk of asthma hospitalization or lowers the threshold for asthma hospitalization.
doi:10.1371/journal.pone.0078816
PMCID: PMC3808299  PMID: 24205324
6.  Maternal Use of Antibiotics and the Risk of Childhood Febrile Seizures: A Danish Population-Based Cohort 
PLoS ONE  2013;8(4):e61148.
Objective
In a large population-based cohort in Denmark to examine if maternal use of antibiotics during pregnancy, as a marker of infection, increases the risk of febrile seizures in childhood in a large population-based cohort in Denmark.
Methods
All live-born singletons born in Denmark between January 1, 1996 and September 25, 2004 and who were alive on the 90th day of life were identified from the Danish National Birth Registry. Diagnoses of febrile seizures were obtained from the Danish National Hospital Register and maternal use of antibiotics was obtained from the National Register of Medicinal Product Statistics. Hazard ratios (HR) and 95% confidence intervals (95% CI) were estimated by Cox proportional hazard regression models.
Results
We followed 551,518 singletons for up to 5 years and identified a total of 21,779 children with a diagnosis of febrile seizures. Slightly increased hazard ratios were observed among most exposure groups when compared to the unexposed group, ex. HR 1.08 95% CI: 1.05–1.11 for use of any systemic antibiotic during pregnancy.
Conclusion
We found weak associations between the use of pharmacologically different antibiotics during pregnancy and febrile seizures in early childhood which may indicate that some infections, or causes or effects of infections, during pregnancy could affect the fetal brain and induce susceptibility to febrile seizures.
doi:10.1371/journal.pone.0061148
PMCID: PMC3627381  PMID: 23613800
7.  Timing of prenatal maternal exposure to severe life events and adverse pregnancy outcomes: A population study of 2.6 million pregnancies 
Psychosomatic medicine  2011;73(3):234-241.
Objective
To identify the impact of timing of prenatal stress exposure on offspring risk for shortened gestational age (GA), preterm birth (PTB), low birth weight (LBW), and small for gestational age (SGA) using a population-based sample.
Methods
Swedish longitudinal population registries were linked to study all individuals born in Sweden 1973–2004. Prenatal maternal stress exposure was defined as death of the father of the child or first degree relative of the mother. Using linear and logistic regression, timing of stress exposure was examined across pregnancy, by month, and by novel periods created based on month of stress exposure findings.
Results
A total of 2,618,777 live-born, singleton infants without congenital anomalies were included; 32,286 exposed to prenatal maternal stress. Examining associations between stress exposure and outcome by the month revealed that risk increases mid-gestation, particularly following months 5 and 6. Combining months 1–4, 5 and 6, and 7–9 as potential periods of differing vulnerability, it was found that stress during period 2 (months 5 and 6) was associated with the greatest risk for shortened GA (−0.52 days, SE=0.15, p=0.0006), PTB (OR=1.24, 99% CI=1.08–1.42), LBW (OR=1.38, 99% CI=1.19–1.61), and SGA (OR=1.25, 99% CI=1.05–1.49).
Conclusions
Risk for shortened GA, PTB, LBW, and SGA are greater following stress exposure during the 5th and/or 6th month of pregnancy. It may be beneficial to refine future analyses to these months. Possible mechanisms include alterations in the hypothalamic-pituitary-adrenal axis and associated stress-responsive molecular regulators.
doi:10.1097/PSY.0b013e31820a62ce
PMCID: PMC3070756  PMID: 21321257
Stress; pregnancy; timing; preterm birth; low birth weight; small for gestational age
8.  Early Life Disease Programming during the Preconception and Prenatal Period: Making the Link between Stressful Life Events and Type-1 Diabetes 
PLoS ONE  2010;5(7):e11523.
Background
To assess the risk of developing Type-1 diabetes among children who were exposed to maternal bereavement during the prenatal or 1-year preconception period.
Methods
We identified N = 1,548,746 singleton births born in Denmark between January 1st 1979 through December 31st 2004, and their next of kin. Altogether, 39,857 children were exposed to bereavement during their prenatal life. The main outcome of interest was hospitalization for type-1 diabetes (ICD 8: 249; ICD 10: E10).
Results
We found the strongest association for type-1 diabetes among children exposed to traumatic father or sibling deaths (aIRR: 2.03, 1.22–3.38); the association was mainly seen for girls (aIRR: 2.91, 1.61–5.26).
Conclusions
We found evidence to suggest that female fetuses exposed to severe prenatal stress are at increased risk for developing type-1 diabetes.
doi:10.1371/journal.pone.0011523
PMCID: PMC2901388  PMID: 20634978
9.  Febrile seizures 
Clinical Evidence  2010;2010:0324.
Introduction
Simple febrile seizures are generalised in onset, last <15 minutes, and do not occur more than once in 24 hours. Complex febrile seizures are longer lasting, have focal symptoms, and can recur within 24 hours. This review only deals with simple febrile seizures. About 2% to 5% of children in the USA and Western Europe, and 6% to 9% of infants and children in Japan will have experienced at least one febrile seizure by the age of 5 years. Simple febrile seizures may slightly increase the risk of developing epilepsy, but have no known adverse effects on behaviour, scholastic performance, or neurocognition.
Methods and outcomes
We conducted a systematic review and aimed to answer the following clinical questions: What are the effects of treatments given during episodes of fever in children with one or more previous simple febrile seizures? What are the effects of long-term (daily, for >1 month) anticonvulsant treatment in children with a history of simple febrile seizures? What are the effects of treatments on reducing the risk of subsequent epilepsy in children with a history of simple febrile seizures? We searched: Medline, Embase, The Cochrane Library, and other important databases up to March 2010 (Clinical Evidence reviews are updated periodically, please check our website for the most up-to-date version of this review). We included harms alerts from relevant organisations such as the US Food and Drug Administration (FDA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA).
Results
We found 18 systematic reviews, RCTs, or observational studies that met our inclusion criteria. We performed a GRADE evaluation of the quality of evidence for interventions.
Conclusions
In this systematic review we present information relating to the effectiveness and safety of the following interventions: anticonvulsants (intermittent or continuous) and antipyretic treatments (physical antipyretic measures, paracetamol, ibuprofen).
Key Points
Febrile seizures are defined as events in infancy or childhood usually occurring between 3 months and 5 years of age associated with a fever, but without evidence of intracranial infection or defined cause for the seizure. Simple febrile seizures are generalised in onset, last <15 minutes, and do not occur more than once in 24 hours. Complex seizures are longer lasting, have focal symptoms, and can recur within 24 hours. This review only deals with simple febrile seizures.About 2% to 5% of children in the USA and Western Europe, and 6% to 9% of infants and children in Japan will have experienced at least one febrile seizure by age 5 years.Simple febrile seizures may slightly increase the risk of developing epilepsy, but have no known adverse effects on behaviour, scholastic performance, or neurocognition.
So far evidence showing whether antipyretic drug treatments or physical methods of temperature reduction are useful in treating episodes of fever to prevent seizure recurrence in children with one or more previous simple febrile seizures is lacking. Intermittent anticonvulsants used in treating episodes of fever to prevent seizure recurrence in children are associated with adverse effects, including hyperactivity, irritability, and difficulties with speech, activity level, or sleep.
Continuous anticonvulsant treatment may be effective for reducing recurrence in children with a history of simple febrile seizures, but is associated with adverse effects; for example, phenobarbital may be associated with cognitive impairments and behavioural adverse effects, including hyperactivity, irritability, and aggressiveness. Serious adverse events that may be associated with sodium valproate include hepatotoxicity and haematological toxicity, both of which may occasionally be fatal. Anticonvulsants do not seem to reduce the risk of epilepsy up to 12 years later in children with a history of simple febrile seizures.
PMCID: PMC3275324  PMID: 21406130
10.  Redefining Outcome of First Seizures by Acute Illness 
Pediatrics  2010;126(6):e1477-e1484.
BACKGROUND
Seizures are common in children, but the causes and recurrence risk for children with a nonfebrile first seizure remain poorly understood.
OBJECTIVE
In a prospective longitudinal study of children who presented with a first-time seizure, we investigated the viral etiology of associated infectious illnesses and sought to determine the risk of recurrent seizures stratified by fever and type of illness.
PATIENTS AND METHODS
Children (aged 6 months to 6 years) were enrolled at the time of evaluation for their first seizure and followed monthly for up to 5 years. Seizure and illness data were collected through parent interviews and medical-record reviews. Stool, serum, and cerebrospinal fluid collected within 48 hours of the first seizure were evaluated for viral gastrointestinal pathogens.
RESULTS
Of the 117 children enrolled, 78 (67%) had febrile seizures, 34 (29%) had nonfebrile-illness seizures, and 5 (4%) had unprovoked seizures. Children with nonfebrile-illness seizures were more likely than those with febrile seizures to have acute gastroenteritis (47% and 28%, respectively; P = .05). No significant differences in seizure recurrence were found between children with or without a fever at first seizure. Children with acute gastroenteritis at first seizure, regardless of fever, had a lower risk of seizure recurrence compared with children with other acute illnesses (hazard ratio: 0.28; 95% confidence interval: 0.09–0.80).
CONCLUSIONS
Our results confirm the role of gastrointestinal illness as a distinguishing feature in childhood seizures. Children with this distinct presentation have a low rate of seizure recurrence and few neurologic complications.
doi:10.1542/peds.2010-1138
PMCID: PMC3040576  PMID: 21098153
seizures; febrile; rotavirus; norovirus; child; gastroenteritis
11.  Febrile seizures 
Clinical Evidence  2008;2008:0324.
Introduction
Simple febrile seizures are generalised in onset, last less than 15 minutes, and do not occur more than once in 24 hours. Complex seizures are longer lasting, have focal symptoms, and can recur within 24 hours. This review only deals with simple febrile seizures. About 2-5% of children in the USA and Western Europe, and 6-9% of infants and children in Japan, will have experienced at least one febrile seizure by the age of 5 years. Simple febrile seizures may slightly increase the risk of developing epilepsy, but have no known adverse effects on behaviour, scholastic performance, or neurocognition.
Methods and outcomes
We conducted a systematic review and aimed to answer the following clinical questions: What are the effects of treatments given during episodes of fever in children with one or more previous simple febrile seizures? What are the effects of long-term (daily, for more than 1 month) anticonvulsant treatment in children with a history of simple febrile seizures? What are the effects of treatments on reducing the risk of subsequent epilepsy in children with a history of simple febrile seizures? We searched: Medline, Embase, The Cochrane Library and other important databases up to August 2007 (BMJ Clinical Evidence reviews are updated periodically, please check our website for the most up-to-date version of this review). We included harms alerts from relevant organisations such as the US Food and Drug Administration (FDA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA).
Results
We found 19 systematic reviews, RCTs, or observational studies that met our inclusion criteria. We performed a GRADE evaluation of the quality of evidence for interventions.
Conclusions
In this systematic review we present information relating to the effectiveness and safety of the following interventions: anticonvulsants (intermittent or continuous), and antipyretic treatments (physical antipyretic measures, paracetamol, ibuprofen).
Key Points
Febrile seizures are defined as events in infancy or childhood usually occurring between 3 months and 5 years of age associated with a fever, but without evidence of intracranial infection, or defined cause for the seizure. Simple febrile seizures are generalised in onset, last less than 15 minutes, and do not occur more than once in 24 hours. Complex seizures are longer lasting, have focal symptoms, and can recur within 24 hours. This review only deals with simple febrile seizures.About 2-5% of children in the USA and Western Europe, and 6-9% of infants and children in Japan will have experienced at least one febrile seizure by age 5 years.Simple febrile seizures may slightly increase the risk of developing epilepsy, but have no known adverse effects on behaviour, scholastic performance, or neurocognition.
We do not know whether antipyretics are useful in treating episodes of fever to prevent seizure recurrence in children with one or more previous simple febrile seizures. Intermittent anticonvulsants used in treating episodes of fever to prevent seizure recurrence in children are associated with adverse effects, including hyperactivity, irritability, and difficulties with speech, activity level, or sleep.
Continuous anticonvulsant treatment may be effective for reducing recurrence in children with a history of simple febrile seizures, but is associated with adverse effects: for example, phenobarbital is associated with cognitive impairments and behavioural adverse effects, including hyperactivity, irritability, and aggressiveness. Anticonvulsants do not appear to reduce the risk of epilepsy up to 12 years later in children with a history of simple febrile seizures.
PMCID: PMC2907951  PMID: 19450310
12.  Maternal Bereavement and Childhood Asthma—Analyses in Two Large Samples of Swedish Children 
PLoS ONE  2011;6(11):e27202.
Background
Prenatal factors such as prenatal psychological stress might influence the development of childhood asthma.
Methodology and Principal Findings
We assessed the association between maternal bereavement shortly before and during pregnancy, as a proxy for prenatal stress, and the risk of childhood asthma in the offspring, based on two samples of children 1–4 (n = 426 334) and 7–12 (n = 493 813) years assembled from the Swedish Medical Birth Register. Exposure was maternal bereavement of a close relative from one year before pregnancy to child birth. Asthma event was defined by a hospital contact for asthma or at least two dispenses of inhaled corticosteroids or montelukast. In the younger sample we calculated hazards ratios (HRs) of a first-ever asthma event using Cox models and in the older sample odds ratio (ORs) of an asthma attack during 12 months using logistic regression. Compared to unexposed boys, exposed boys seemed to have a weakly higher risk of first-ever asthma event at 1–4 years (HR: 1.09; 95% confidence interval [CI]: 0.98, 1.22) as well as an asthma attack during 12 months at 7–12 years (OR: 1.10; 95% CI: 0.96, 1.24). No association was suggested for girls. Boys exposed during the second trimester had a significantly higher risk of asthma event at 1–4 years (HR: 1.55; 95% CI: 1.19, 2.02) and asthma attack at 7–12 years if the bereavement was an older child (OR: 1.58; 95% CI: 1.11, 2.25). The associations tended to be stronger if the bereavement was due to a traumatic death compared to natural death, but the difference was not statistically significant.
Conclusions/Significance
Our results showed some evidence for a positive association between prenatal stress and childhood asthma among boys but not girls.
doi:10.1371/journal.pone.0027202
PMCID: PMC3210147  PMID: 22087265
13.  Early life bereavement and childhood cancer: a nationwide follow-up study in two countries 
BMJ Open  2013;3(5):e002864.
Objective
Childhood cancer is a leading cause of child deaths in affluent countries, but little is known about its aetiology. Psychological stress has been suggested to be associated with cancer in adults; whether this is also seen in childhood cancer is largely unknown. We investigated the association between bereavement as an indicator of severe childhood stress exposure and childhood cancer, using data from Danish and Swedish national registers.
Design
Population-based cohort study.
Setting
Denmark and Sweden.
Participants
All live-born children born in Denmark between 1968 and 2007 (n=2 729 308) and in Sweden between 1973 and 2006 (n=3 395 166) were included in this study. Exposure was bereavement by the death of a close relative before 15 years of age. Follow-up started from birth and ended at the first of the following: date of a cancer diagnosis, death, emigration, day before their 15th birthday or end of follow-up (2007 in Denmark, 2006 in Sweden).
Outcome measures
Rates and HRs for all childhood cancers and specific childhood cancers.
Results
A total of 1 505 938 (24.5%) children experienced bereavement at some point during their childhood and 9823 were diagnosed with cancer before the age of 15 years. The exposed children had a small (10%) increased risk of childhood cancer (HR 1.10; 95% CI 1.04 to 1.17). For specific cancers, a significant association was seen only for central nervous system tumours (HR 1.14; 95% CI 1.02 to 1.28).
Conclusions
Our data suggest that psychological stress in early life is associated with a small increased risk of childhood cancer.
doi:10.1136/bmjopen-2013-002864
PMCID: PMC3664350  PMID: 23793702
Childhood cancer; bereavement; psychological stress; risk factor; follow up
14.  Family history and recurrence of febrile seizures. 
Archives of Disease in Childhood  1994;70(5):395-399.
To determine the value of a detailed family history for the assessment of the risk of recurrence of febrile seizures, 115 children who visited the emergency room of an academic children's hospital were studied prospectively. The recurrence risk of febrile seizures was analysed in relation to the child's family history and the proportion of relatives affected by febrile seizures using Kaplan-Meier estimates and Cox proportional hazard models. A first degree family history positive for febrile seizures (parents or siblings affected by febrile seizures) increased a child's two year recurrence risk from 27 to 52%. No significant increase of recurrence risk for febrile seizures was found in children with second degree relatives (grandparents and uncles/aunts) or cousins only affected by febrile seizures. Recurrence risk was significantly correlated with the proportion of first degree relatives affected by febrile seizures: risks were 27, 40, and 83% in children whose proportion was 0, 0-0.5, and > or = 0.5 respectively. Analysis of the recurrence risk in relation to a weighted proportion, adjusted for the attained age and sex of first degree relatives, showed similar results. It is concluded that the application of the proportion of first degree relatives affected by febrile seizures generates a more differentiated assessment of the recurrence risk of febrile seizures.
PMCID: PMC1029827  PMID: 8017960
15.  In-Utero Exposure to Bereavement and Offspring IQ: A Danish National Cohort Study 
PLoS ONE  2014;9(2):e88477.
Background
Intelligence is a life-long trait that has strong influences on lifestyle, adult morbidity and life expectancy. Hence, lower cognitive abilities are therefore of public health interest. Our primary aim was to examine if prenatal bereavement measured as exposure to death of a close family member is associated with the intelligence quotient (IQ) scores at 18-years of age of adult Danish males completing a military cognitive screening examination.
Methods
We extracted records for the Danish military screening test and found kinship links with biological parents, siblings, and maternal grandparents using the Danish Civil Registration System (N = 167,900). The prenatal exposure period was defined as 12 months before conception until birth of the child. We categorized children as exposed in utero to severe stress (bereavement) during prenatal life if their mothers lost an elder child, husband, parent or sibling during the prenatal period; the remaining children were included in the unexposed cohort. Mean score estimates were adjusted for maternal and paternal age at birth, residence, income, maternal education, gestational age at birth and birth weight.
Results
When exposure was due to death of a father the offsprings' mean IQ scores were lower among men completing the military recruitment exam compared to their unexposed counterparts, adjusted difference of 6.5 standard IQ points (p-value = 0.01). We did not observe a clinically significant association between exposure to prenatal maternal bereavement caused by death of a sibling, maternal uncle/aunt or maternal grandparent even after stratifying deaths only due to traumatic events.
Conclusion
We found maternal bereavement to be adversely associated with IQ in male offspring, which could be related to prenatal stress exposure though more likely is due to changes in family conditions after death of the father. This finding supports other literature on maternal adversity during fetal life and cognitive development in the offspring.
doi:10.1371/journal.pone.0088477
PMCID: PMC3928249  PMID: 24558394
16.  Risk Factors of the First Febrile Seizures in Iranian Children 
Objective. Febrile seizures are the most common type of convulsion in children. The identification of influencing factors on incidence of the first febrile seizures is of prime priority. The aim of this study was to identify the risk factors of the first febrile seizures in Iranian children. Methods. In this case-control study 80 children aged 9 month to 5 years with their first febrile seizures were compared with 80 children with fever without seizure based on different risk factors in 2007. Results. There was significant difference between two groups regarding the gender, family history of febrile seizures, breast-feeding duration, and the body temperature (P < .05). Conclusion. Our study showed that factors including the gender, family history of febrile seizures, breast-feeding duration, and the body temperature are among the risk factors in occurrence of the first febrile seizure. Preventive measures to remove such risk factors could lead to lower the incidence of febrile seizures.
doi:10.1155/2010/862897
PMCID: PMC2905933  PMID: 20652051
17.  Prenatal corticosteroid exposure alters early developmental seizures and behavior 
Epilepsy research  2011;95(1-2):9-19.
In humans, corticosteroids are often administered prenatally to improve lung development in preterm neonates. Studies in exposed children as well as in children, whose mothers experienced significant stress during pregnancy indicate behavioral problems and possible increased occurrence of epileptic spasms. This study investigated whether prenatal corticosteroid exposure alters early postnatal seizure susceptibility and behaviors. On gestational day 15, pregnant rats were injected i.p. with hydrocortisone (2× 10 mg/kg), betamethasone (2× 0.4 mg/kg) or vehicle. On postnatal day (P)15, seizures were induced by flurothyl or kainic acid (3.5 or 5.0 mg/kg). Horizontal bar holding was determined prior to seizures and again on P17. Performance in the elevated plus maze was assessed on P20-22. Prenatal exposure to betamethasone decreased postnatal susceptibility to flurothyl-induced clonic seizures but not to kainic acid-induced seizures. Prenatal hydrocortisone decreased postnatal weight but did not affect seizure susceptibility. Hydrocortisone alone did not affect performance in behavioral tests except for improving horizontal bar holding on P17. A combination of prenatal hydrocortisone and postnatal seizures resulted in increased anxiety. Prenatal exposure to mineralocorticoid receptor blocker canrenoic acid did not attenuate, but surprisingly amplified the effects of hydrocortisone on body weight and significantly worsened horizontal bar performance. Thus, prenatal exposure to excess corticosteroids alters postnatal seizure susceptibility and behaviors. Specific effects may depend on corticosteroid species.
doi:10.1016/j.eplepsyres.2011.01.019
PMCID: PMC3109105  PMID: 21429712
betamethasone; hydrocortisone; kainic acid; flurothyl; anxiety
18.  Recurrence risk after first febrile seizure and effect of short term diazepam prophylaxis. 
Archives of Disease in Childhood  1985;60(11):1045-1049.
In a prospective randomised study, 289 children admitted consecutively to hospital with their first febrile seizure were allocated, by date of admission, to short term diazepam prophylaxis (n = 152) or to no prophylaxis (n = 137) and followed for 18 months. In untreated children, five major risk factors for recurrent febrile convulsions were identified: age 15 months or less at the time of the first febrile seizure, epilepsy in first degree relatives, febrile convulsions in first degree relatives, a first complex febrile seizure, and day nursery care. The 18 month recurrence rate was 80 to 100% if three to five risk factors were present, 50% if two factors were identified, 25% where one factor was found, and 12% if there were no predictors. During prophylaxis the recurrence rate was uniformly low (mean 12%) in all risk groups. In high (three or more factors) and intermediate (two factors) risk children prophylaxis provided effective seizure control and reduced the recurrence rate from 80%, or more, to 12% and 50% to 12%, respectively. In children with one risk factor 50% of all recurrences were prevented (25% to 12%). Prophylaxis was ineffective in very low risk children (12% to 12%).
PMCID: PMC1777614  PMID: 3907504
19.  Pre- and Postnatal Parental Smoking and Acute Otitis Media in Early Childhood 
Aim
To explore associations between acute otitis media in early childhood and prenatal and postnatal tobacco smoke exposure.
Methods
Subjects were 32,077 children born 2000 – 2005 in the Norwegian Mother and Child Study with questionnaire data on tobacco smoke exposure and acute otitis media up to 18 months of age. Multivariate regression models were used to obtain adjusted relative risks for acute otitis media.
Results
Acute otitis media was slightly more common in children exposed to parental smoking. The incidence from 0–6 months was 4.7% in unexposed children, and 6.0% in children exposed both pre-and postnatally. After adjusting for postnatal exposure and covariates, the relative risk for acute otitis media 0–6 months when exposed to maternal smoking in pregnancy was 1.34, 95% confidence interval: 1.06–1.69. Maternal smoking in pregnancy was associated with acute otitis media up to 12 months of age. Compared to non-exposed children, there was a slightly increased risk of recurrent acute otitis media for children exposed both pre- and postnatally with a relative risk of 1.24, 95% confidence interval: 1.01–1.52,.
Conclusion
Even in a cohort with relatively low exposure levels of parental smoking, maternal smoking in pregnancy was associated with an increased risk of acute otitis media in early childhood.
doi:10.1111/j.1651-2227.2009.01506.x
PMCID: PMC2993880  PMID: 19764924
Acute otitis media; Smoking; Pregnancy; Norway; Cohort studies
20.  Prenatal Exposure to Antiepileptic Drugs and Dental Agenesis 
PLoS ONE  2014;9(1):e84420.
Objective
The aim of the study was to investigate the association between prenatal exposure to AEDs and the risk of dental agenesis and to differentiate between the possible effects of the different drugs used.
Methods
Data on 214 exposed and 255 unexposed children, aged 12–18 years, were extracted from the Prescription Database of the Central Denmark Region and North Denmark Region and the Danish Medical Birth Registry. The children's dental charts were examined for the presence of dental agenesis.
Results
Overall, children exposed to AED in utero had an increased risk of developing dental agenesis, but as a group, the difference was not significant (OR = 1.7; [95% CI: 0.8–3.6]). The risk of developing dental agenesis was three-fold increased (OR = 3.1; [95% CI: 1.3–7.4]) in children exposed to valproate in mono- or in poly-therapy with other AEDs than carbamazepine or oxcarbazepine. The risk was further increased (OR = 11.2; [95% CI: 2.4–51.9]) in children exposed to valproate and carbamazepine or oxcarbazepine in combination.
Conclusions
The present study shows that dental agenesis is a potential congenital abnormality that is related to prenatal exposure to valproate, and dental agenesis may be considered a sensitive marker for the teratogenicity of valproate.
doi:10.1371/journal.pone.0084420
PMCID: PMC3885552  PMID: 24416231
21.  Long-Term Health Outcomes in Children Born to Mothers with Diabetes: A Population-Based Cohort Study 
PLoS ONE  2012;7(5):e36727.
Background
To examine whether prenatal exposure to parental type 1 diabetes, type 2 diabetes, or gestational diabetes is associated with an increased risk of malignant neoplasm or diseases of the circulatory system in the offspring.
Methods/Principal Findings
We conducted a population-based cohort study of 1,781,576 singletons born in Denmark from 1977 to 2008. Children were followed for up to 30 years from the day of birth until the onset of the outcomes under study, death, emigration, or December 31, 2009, whichever came first. We used Cox proportional hazards model to estimate hazard ratios (HR) with 95% confidence intervals (95% CI) for the outcomes under study while adjusting for potential confounders. An increased risk of malignant neoplasm was found in children prenatally exposed to maternal type 2 diabetes (HR = 2.2, 95%CI: 1.5–3.2). An increased risk of diseases of the circulatory system was found in children exposed to maternal type 1 diabetes (HR = 2.2, 95%CI: 1.6–3.0), type 2 diabetes (HR = 1.4, 95%CI: 1.1–1.7), and gestational diabetes (HR = 1.3, 95%CI: 1.1–1.6), but results were attenuated after excluding children with congenital malformations. An increased risk of diseases of the circulatory system was also found in children exposed to paternal type 2 diabetes (HR = 1.5, 95%CI: 1.1–2.2) and the elevated risk remained after excluding children with congenital malformations.
Conclusions
This study suggests that susceptibility to malignant neoplasm is modified partly by fetal programming. Diseases of the circulatory system may be modified by genetic factors, other time-stable family factors, or fetal programming.
doi:10.1371/journal.pone.0036727
PMCID: PMC3359312  PMID: 22649497
22.  Severe bereavement stress during the prenatal and childhood periods and risk of psychosis in later life: population based cohort study 
Objective To examine the risk of psychosis associated with severe bereavement stress during the antenatal and postnatal period, between conception to adolescence, and with different causes of death.
Design Population based cohort study.
Setting Swedish national registers including births between 1973 and 1985 and followed-up to 2006.
Participants In a cohort of 1 045 336 Swedish births (1973-85), offspring born to mothers exposed to severe maternal bereavement stress six months before conception or during pregnancy, or exposed to loss of a close family member subsequently from birth to 13 years of age were followed until 2006. Admissions were identified by linkage to national patient registers.
Main outcome measures Crude and adjusted odds ratios for all psychosis, non-affective psychosis, and affective psychosis.
Results Maternal bereavement stress occurring preconception or during the prenatal period was not associated with a significant excess risk of psychosis in offspring (adjusted odds ratio, preconception 1.24, 95% confidence interval 0.96 to 1.62; first trimester 0.95, 0.58 to1.56; second trimester 0.79, 0.46 to 1.33; third trimester 1.14, 0.78 to 1.66). Risks increased modestly after exposure to the loss of a close family member from birth to adolescence for all psychoses (adjusted odds ratio 1.17, 1.04 to 1.32). The pattern of risk was generally similar for non-affective and affective psychosis. Thus estimates were higher after death in the nuclear compared with extended family but remained non-significant for prenatal exposure; the earlier the exposure to death in the nuclear family occurred in childhood (all psychoses: adjusted odds ratio, birth to 2.9 years 1.84, 1.41 to 2.41; 3-6.9 years 1.47, 1.16 to 1.85; 7-12.9 years 1.32, 1.10 to 1.58) and after suicide. Following suicide, risks were especially higher for affective psychosis (birth to 2.9 years 3.33, 2.00 to 5.56; 6.9 years 1.84, 1.04 to 3.25; 7-12.9 years 2.68, 1.84 to 3.92). Adjustment for key confounders attenuated but did not explain associations with risk.
Conclusions Postnatal but not prenatal bereavement stress in mothers is associated with an increased risk of psychosis in offspring. Risks are especially high for affective psychosis after suicide in the nuclear family, an effect that is not explained by family psychiatric history. Future studies are needed to understand possible sources of risk and resilience so that structures can be put in place to support vulnerable children and their families.
doi:10.1136/bmj.f7679
PMCID: PMC3898661  PMID: 24449616
23.  A longitudinal study of the long-term consequences of drinking during pregnancy: heavy in utero alcohol exposure disrupts the normal processes of brain development 
Exposure to alcohol in utero can cause birth defects including face and brain abnormalities, and is the most common preventable cause of intellectual disabilities. Here we use structural magnetic resonance imaging (MRI) to measure cortical volume change longitudinally in a cohort of human children and youth with prenatal alcohol exposure (PAE) and a group of unexposed control subjects, demonstrating that the normal processes of brain maturation are disrupted in individuals whose mothers drank heavily during pregnancy. Trajectories of cortical volume change within children and youth with PAE differed from those of unexposed control subjects in posterior brain regions, particularly in the parietal cortex. In these areas, control children appear to show a particularly plastic cortex with a prolonged pattern of cortical volume increases followed by equally vigorous volume loss during adolescence, while the alcohol-exposed participants showed primarily volume loss, demonstrating decreased plasticity. Furthermore, smaller volume changes between scans were associated with lower intelligence and worse facial morphology in both groups, and were related to the amount of PAE during each trimester of pregnancy in the exposed group. This demonstrates that measures of IQ and facial dysmorphology predict, to some degree, the structural brain development that occurs in subsequent years. These results are encouraging in that interventions aimed at altering “experience” over time may improve brain trajectories in individuals with heavy PAE, and possibly other neurodevelopmental disorders.
doi:10.1523/JNEUROSCI.1161-12.2012
PMCID: PMC3515671  PMID: 23115162
24.  Cognitive Outcome of Offspring from Dexamethasone-Treated Pregnancies at Risk for Congenital Adrenal Hyperplasia Due to 21-Hydroxylase Deficiency 
European Journal of Endocrinology  2012;167(1):103-110.
Objectives
To test whether dexamethasone (DEX) treatment of pregnancies at risk for congenital adrenal hyperplasia (CAH) impairs cognitive functioning in the offspring.
Design
Observational follow-up of prenatally DEX-exposed offspring and controls.
Methods
Study 1 included 140 children age 5-12 years: 67 DEX-exposed (long-term: 8 CAH girls) and 73 unexposed (with 15 CAH girls). Study 2 included 20 participants age 11-24 years: 7 DEX-exposed (long-term: 1 CAH woman) and 13 unexposed (with 4 CAH women). Neuropsychological testing was done in hospital settings or patients' homes. Data analysis aimed at maximizing detection of effects of DEX exposure.
Results
The vast majority of group comparisons were not marginally or conventionally significant. The few significant findings on short-term prenatal DEX exposure suggested more positive than adverse outcomes. By contrast, the few significant findings in females with CAH and long-term DEX exposure indicated slower mental processing than in controls on several neuropsychological variables, although partial correlations of DEX-exposure duration with cognitive outcome did not corroborate this association.
Conclusions
Our studies do not replicate a previously reported adverse effect of short-term prenatal DEX exposure on working memory, while our findings on cognitive function in CAH girls with long-term DEX exposure contribute to concerns about potentially adverse cognitive aftereffects of such exposure. Yet, our studies are not definitive, and replications in larger samples are required.
doi:10.1530/EJE-11-0789
PMCID: PMC3383400  PMID: 22549088
25.  Wheezing, asthma, hay fever, and atopic eczema in relation to maternal occupations in pregnancy 
Objectives
To examine whether prenatal occupational exposures, especially to organic solvents, are associated with atopic diseases in childhood.
Methods
The study comprised children born in Odense or Aalborg, Denmark between 1984 and 1987. Occupational job titles were derived from questionnaires filled out by the mothers when attending midwife centres. Assessment of organic solvent exposures was based on job titles selected by occupational specialists. A follow up questionnaire to the parents provided data on medical diagnoses as well as wheezing symptoms for 7844 children aged 14–18. Multivariate logistic regression analyses were performed to estimate the cumulative risk for wheezing (early wheezing not diagnosed as asthma), asthma, hay fever, and atopic eczema during childhood by means of odds ratios (OR) and 95% confidence intervals (CI).
Results
Explorative analyses by maternal job titles in pregnancy showed elevated odds ratios concerning different atopic diseases for occupational groups such as “bakers, pastry cooks, and confectionary makers”, “dental assistants”, “electrical and electronic assemblers”, “sewers and embroiders”, and “bookbinders and related workers”. An excess risk ratio for hay fever (OR 2.8, CI 1.1 to 7.5) was found following maternal gestational exposure to organic solvents. Furthermore, a slightly raised odds ratio for asthma was observed in children of shift workers (OR 1.2, CI 1.0 to 1.5).
Conclusion
The data suggest links between certain maternal occupations during pregnancy and atopic diseases, which merits further scrutiny. However, no consistent pattern was seen across the different atopic diseases.
doi:10.1136/oem.2005.024422
PMCID: PMC2078155  PMID: 16757508
solvents; prenatal exposure delayed effects; hypersensitivity

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