Global cesarean section (CS) rates range from 1% to 52%, with a previous CS being the commonest indication. Labour following a previous CS carries risk of scar rupture, with potential for offspring hypoxic brain injury, leading to high rates of repeat elective CS. However, the effect of delivery by CS on long-term outcomes in children is unclear. Increasing evidence suggests that in avoiding exposure to maternal bowel flora during labour or vaginal birth, offspring delivered by CS may be adversely affected in terms of energy uptake from the gut and immune development, increasing obesity and asthma risks, respectively. This study aimed to address the evidence gap on long-term childhood outcomes following repeat CS by comparing adverse childhood health outcomes after (1) planned repeat CS and (2) unscheduled repeat CS with those that follow vaginal birth after CS (VBAC).
Methods and Findings
A data-linkage cohort study was performed. All second-born, term, singleton offspring delivered between 1 January 1993 and 31 December 2007 in Scotland, UK, to women with a history of CS (n = 40,145) were followed up until 31 January 2015. Outcomes assessed included obesity at age 5 y, hospitalisation with asthma, learning disability, cerebral palsy, and death. Cox regression and binary logistic regression were used as appropriate to compare outcomes following planned repeat CS (n = 17,919) and unscheduled repeat CS (n = 8,847) with those following VBAC (n = 13,379).
Risk of hospitalisation with asthma was greater following both unscheduled repeat CS (3.7% versus 3.3%, adjusted hazard ratio [HR] 1.18, 95% CI 1.05–1.33) and planned repeat CS (3.6% versus 3.3%, adjusted HR 1.24, 95% CI 1.09–1.42) compared with VBAC. Learning disability and death were more common following unscheduled repeat CS compared with VBAC (3.7% versus 2.3%, adjusted odds ratio 1.64, 95% CI 1.17–2.29, and 0.5% versus 0.4%, adjusted HR 1.50, 95% CI 1.00–2.25, respectively). Risk of obesity at age 5 y and risk of cerebral palsy were similar between planned repeat CS or unscheduled repeat CS and VBAC. Study limitations include the risk that women undergoing an unscheduled CS had intended to have a planned CS, and lack of data on indication for CS, which may confound the findings.
Birth by repeat CS, whether planned or unscheduled, was associated with an increased risk of hospitalisation with asthma but no difference in risk of obesity at age 5 y. Greater risk of death and learning disability following unscheduled repeat CS compared to VBAC may reflect complications during labour. Further research, including meta-analyses of studies of rarer outcomes (e.g., cerebral palsy), are needed to confirm whether such risks are similar between delivery groups.
Women who have had a previous cesarean section (CS) face a slightly elevated risk of negative outcomes during a subsequent vaginal birth. This is because, in rare cases, the abdominal CS scar ruptures during labor, which may cause complications and serious problems, such as oxygen deprivation to the brain of a child. As a result, pregnant women who have had a previous CS and their doctors sometimes make a decision to plan a repeat CS instead of a vaginal birth after cesarean section (VBAC). Besides vaginal birth being “more natural,” some studies have suggested that exposure to the mother’s microbiome (the bacteria and fungi that live in the vagina and gut) in the birth canal might be important for the healthy development of the infant’s own microbiome and its immune system. Consistent with this notion, some studies have reported higher levels of allergies (including eczema and asthma) and overweight or obesity in children born by CS.
Why Was This Study Done?
Scotland keeps detailed records of births and childhood health data, which allow researchers to study possible links between type of birth and subsequent childhood health outcomes. In this study, the researchers focused on singleton births (as opposed to twins, triplets, etc.) to mothers who have had a previous CS. In this group, where the decision about a preferred delivery mode is likely made before labor starts, they examined how childhood health outcomes compared between repeat CS and VBAC.
What Did the Researchers Do and Find?
The researchers studied all second births between 1 January 1993 and 31 December 2007 of singleton children to mothers in Scotland who had previously had a first child born by CS. Using available health records, they categorized these second births into scheduled repeat CS (assumed to be planned), unscheduled repeat CS, and VBAC. They then examined the childrens’ health records until 31 January 2015 and looked for correlations between type of birth and the following outcomes: obesity at age five years, hospitalization with asthma, prescription of a salbutamol inhaler (an asthma medication) at age five, hospitalization with inflammatory bowel disease, type 1 diabetes, learning disability, cerebral palsy, cancer, and death.
Of 40,145 births that took place, 44.6% were scheduled repeat CS, 22.1% were unscheduled repeat CS, and 33.3% were VBAC. The only consistent difference the researchers found between repeat CS (scheduled or unscheduled) and VBAC was a slightly elevated risk for hospitalization with asthma in children born by CS. They felt that this was not clinically significant, especially as there was no difference in the rate of salbutamol inhaler prescription. The risk of obesity at age five was similar between children born by repeat CS (scheduled or unscheduled) and those born by VBAC. Learning disability and death were more common following unscheduled repeat CS, but not scheduled repeat CS, than following VBAC.
What Do These Findings Mean?
Overall, the right decision about a planned birth mode, vaginal or cesarean, depends on the individual case of mother and child. If mothers with a previous CS plan a vaginal birth, they should do so in a hospital that is prepared to perform a CS at short notice in case of scar rupture. The findings here suggest that there are no substantially worse outcomes associated with planned repeat cesarean births. They therefore support a process of planning birth after a previous CS that reflects a woman’s values and preferences. Whether the births analyzed in this study were initially planned to be vaginal or CS is not known. The researchers assumed an intended CS was one that was scheduled ahead of time and performed on the scheduled date. All other CSs were categorized as unplanned and likely represent a mix of emergency CS ahead of a planned CS and emergency CS after complications during a planned vaginal birth. The reasons for the observed higher risk of learning disability and death following unscheduled repeat CS are not clear because the records did not include the indication (i.e., the medical reason) for a CS, but the results are consistent with the known higher risk of an emergency CS to mothers and children.
The risks and benefits of different birth modes, especially in view of exposure to the mother’s microbiome, are active areas of research. The results here disagree with some earlier studies in different settings, but these were unable to adjust for some factors that can affect child health that are taken into account here, such as whether mothers were obese, smoked, or had asthma. The findings of this study are consistent with a study by the same researchers that analyzed all singleton first births from the Scottish health records and found slightly increased asthma rates, but no increased obesity or type 1 diabetes, in young children who had been delivered by CS compared with those who had a vaginal birth.
This list of resources contains links that can be accessed when viewing the PDF on a device or via the online version of the article at http://dx.doi.org/10.1371/journal.pmed.1001973.
The Royal College of Obstetricians and Gynaecologists in the UK has a practice guideline and patient information leaflet on birth after cesarean section
The American Congress of Obstetricians and Gynecologists has a practice bulletin for vaginal birth after previous cesarean delivery, women’s health resources related to vaginal birth after cesarean, and women’s health resources related to cesarean section in general
Wikipedia has a page on delivery after previous cesarean section (note that Wikipedia is an online encyclopedia that anyone can edit)
The Royal Australian and New Zealand College of Obstetricians and Gynaecologists has a statement on birth after previous cesarean section
The Institute of Obstetricians and Gynaecologists of the Royal College of Physicians of Ireland has a clinical practice guideline on delivery after cesarean section