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1.  The Midland and North of England Stillbirth Study (MiNESS) 
Background
The United Kingdom has one of the highest rates of stillbirth in Europe, resulting in approximately 4,000 stillbirths every year. Potentially modifiable risk factors for late stillbirths are maternal age, obesity and smoking, but the population attributable risk associated with these risk factors is small.
Recently the Auckland Stillbirth Study reported that maternal sleep position was associated with late stillbirth. Women who did not sleep on their left side on the night before the death of the baby had double the risk compared with sleeping on other positions. The population attributable risk was 37%. This novel observation needs to be replicated or refuted.
Methods/Design
Case control study of late singleton stillbirths without congenital abnormality. Controls are women with an ongoing singleton pregnancy, who are randomly selected from participating maternity units booking list of pregnant women, they are allocated a gestation for interview based on the distribution of gestations of stillbirths from the previous 4 years for the unit. The number of controls selected is proportional to the number of stillbirths that occurred at the hospital over the previous 4 years.
Data collection: Interviewer administered questionnaire and data extracted from medical records. Sample size: 415 cases and 830 controls. This takes into account a 30% non-participation rate, and will detect an OR of 1.5 with a significance level of 0.05 and power of 80% for variables with a prevalence of 57%, such as non-left sleeping position.
Statistical analysis: Mantel-Haenszel odds ratios and unconditional logistic regression to adjust for potential confounders.
Discussion
The hypotheses to be tested here are important, biologically plausible and amenable to a public health intervention. Although this case–control study cannot prove causation, there is a striking parallel with research relating to sudden infant death syndrome, where case–control studies identified prone sleeping position as a major modifiable risk factor. Subsequently mothers were advised to sleep babies prone (“Back to Sleep” campaign), which resulted in a dramatic drop in SIDS. This study will provide robust evidence to help determine whether such a public health intervention should be considered.
Trial registration number
NCT02025530
doi:10.1186/1471-2393-14-171
PMCID: PMC4032501  PMID: 24885461
Stillbirth; Perinatal mortality; Perinatal death; Risk factors; Sleep position; Reduced fetal movements; Fetal growth restriction
2.  A triple risk model for unexplained late stillbirth 
Background
The triple risk model for sudden infant death syndrome (SIDS) has been useful in understanding its pathogenesis. Risk factors for late stillbirth are well established, especially relating to maternal and fetal wellbeing.
Discussion
We propose a similar triple risk model for unexplained late stillbirth. The model proposed by us results from the interplay of three groups of factors: (1) maternal factors (such as maternal age, obesity, smoking), (2) fetal and placental factors (such as intrauterine growth retardation, placental insufficiency), and (3) a stressor (such as venocaval compression from maternal supine sleep position, sleep disordered breathing). We argue that the risk factors within each group in themselves may be insufficient to cause the death, but when they interrelate may produce a lethal combination.
Summary
Unexplained late stillbirth occurs when a fetus who is somehow vulnerable dies as a result of encountering a stressor and/or maternal condition in a combination which is lethal for them.
doi:10.1186/1471-2393-14-142
PMCID: PMC3991879  PMID: 24731396
Stillbirth; Triple risk; Vulnerable fetus
3.  A postal survey of maternal sleep in late pregnancy 
Background
Sleep disturbances in late pregnancy are common. This study aimed to survey sleep problems in third trimester pregnant women and to compare sleep in the pre-pregnancy period with the third trimester.
Methods
Third-trimester women (n=650) were sent a postal survey containing questions relating to sleep experience, including perceived sleep quality, sleep difficulties, night waking, sleep environment, snoring, daytime tiredness and daytime napping. Time periods reported on were before pregnancy and in the last week.
Results
Respondents numbered 244 (38%). Before pregnancy, the mean reported duration of night-time sleep was 8.1 (SD 1.1) hours; in the last week this had decreased to 7.5 (SD 1.8) hours (p<.0001). Only 29% rated their sleep quality in the last week as very good or fairly good, compared with 82% rating their sleep this way before the pregnancy. The main reasons for sleeping difficulties were discomfort (67%) and pain (36%). Snoring increased significantly over the course of the pregnancy, with 37% reporting snoring often or every night in the last week. Those with a pre-pregnancy body mass index of greater than 25 were significantly more likely to snore (p=.01). Only 4% of women had an abnormal Epworth Sleepiness Scale score (i.e. >10) prior to pregnancy, whereas in the last week 33% scored in the abnormal range. Likewise, 5% had regularly napped during the daytime before pregnancy, compared with 41% in the last week.
Conclusions
Sleep problems are common in women in late pregnancy, and increase markedly compared with before pregnancy.
doi:10.1186/1471-2393-12-144
PMCID: PMC3541269  PMID: 23228137
Pregnancy; Sleep disturbances; Sleep quality; Snoring; Daytime sleepiness
4.  Sleep position and risk of late stillbirth 
BMC Pregnancy and Childbirth  2012;12(Suppl 1):A12.
doi:10.1186/1471-2393-12-S1-A12
PMCID: PMC3428675
5.  Concluding remarks 
BMC Pregnancy and Childbirth  2012;12(Suppl 1):A14.
doi:10.1186/1471-2393-12-S1-A14
PMCID: PMC3428676
7.  Emerging ideas to better understand and prevent stillbirths 
BMC Pregnancy and Childbirth  2012;12(Suppl 1):A1.
doi:10.1186/1471-2393-12-S1-A1
PMCID: PMC3428684  PMID: 22950795
8.  Relationship between obesity, ethnicity and risk of late stillbirth: a case control study 
Background
In high income countries there has been little improvement in stillbirth rates over the past two decades. Previous studies have indicated an ethnic disparity in the rate of stillbirths. This study aimed to determine whether maternal ethnicity is independently associated with late stillbirth in New Zealand.
Methods
Cases were women with a singleton, late stillbirth (≥28 weeks' gestation) without congenital abnormality, born between July 2006 and June 2009 in Auckland, New Zealand. Two controls with ongoing pregnancies were randomly selected at the same gestation at which the stillbirth occurred. Women were interviewed in the first few weeks following stillbirth, or at the equivalent gestation for controls. Detailed demographic data were recorded. The study was powered to detect an odds ratio of 2, with a power of 80% at the 5% level of significance, given a prevalence of the risk factor of 20%. A multivariable regression model was developed which adjusted for known risk factors for stillbirth, as well as significant risk factors identified in the current study, and adjusted odds ratios and 95% confidence intervals were calculated.
Results
155/215 (72%) cases and 310/429 (72%) controls consented. Pacific ethnicity, overweight and obesity, grandmultiparity, not being married, not being in paid work, social deprivation, exposure to tobacco smoke and use of recreational drugs were associated with an increased risk of late stillbirth in univariable analysis. Maternal overweight and obesity, nulliparity, grandmultiparity, not being married and not being in paid work were independently associated with late stillbirth in multivariable analysis, whereas Pacific ethnicity was no longer significant (adjusted Odds Ratio 0.99; 0.51-1.91).
Conclusions
Pacific ethnicity was not found to be an independent risk factor for late stillbirth in this New Zealand study. The disparity in stillbirth rates between Pacific and European women can be attributed to confounding factors such as maternal obesity and high parity.
doi:10.1186/1471-2393-11-3
PMCID: PMC3027197  PMID: 21226915

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