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Increased risk of stillbirth, ectopic pregnancy linked with primary C-sections

Publish date: July 1, 2014

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Study findings are unsurprising, with uncertain clinical relevance

Despite the increase in the

number of cesarean deliveries around the world over the past decades, there is

not a clinically significant increase in attendant maternal-fetal

complications. Thus, although the Danish study findings are neither novel nor

surprising, ultimately this study supports the observation that cesarean

delivery is another safe route for both the mother and child. It also is crucial

to recognize that this study is not a strict comparison of whether vaginal

delivery is safer than cesarean delivery, but an examination of how C-sections

may be linked to subsequent pregnancy complications.

The data for ectopic pregnancies presented in this

study have only marginal statistical relevance, but not a great clinical

significance. Additionally, a woman’s prior gynecologic history, such as

infections or surgical scarring due to the C-section procedure, greatly

influences the risk for ectopic pregnancy. Because many ectopic pregnancies can

abort prior to the detection of pregnancy, drawing any major conclusions from

these results is quite difficult.

It also is unclear to what extent the incomplete data

could influence how we interpret the findings of this study. As the fields of

developmental biology, teratology, biochemistry, and reproductive immunology

have advanced, so too has our understanding of the complex mechanisms involved

in successful pregnancy outcomes. Basing clinical applications on the findings from

this study, where gaps exist in the investigators’ knowledge of the women’s

overall health, becomes much more nebulous, and any conclusions should be

cautiously made and not extrapolated too much.

Dr. E. Albert Reece, Ph.D., MBA, is vice president for medical affairs at the University of Maryland, Baltimore, the John Z. and Akiko K. Bowers Distinguished Professor and dean of the school of medicine. He made these comments in an interview.


 

FROM PLOS MEDICINE

"Almost 50% of the explained stillbirths in this cohort were due to antenatal complications (including placental abruption/infarction, intrauterine growth restriction, preeclampsia, prematurity, and poor placental growth)," the researchers wrote. "The clinical importance is that although many of these complications are largely not preventable, an increased awareness that the fetus is at risk may facilitate increased surveillance and optimally timed delivery and may lead to improved perinatal outcomes."

The increased risk of ectopic pregnancy (HR 1.09) with overall primary C-sections translated to an absolute risk increase of 0.1% and number needed to harm of 1,000 women. The increased risk was similar for emergency (HR 1.09) and elective (HR 1.12) C-sections, both statistically significant. Overall, primary C-sections were not associated with miscarriage, and miscarriage risk was decreased (HR 0.72) for maternally requested C-sections.

The authors reported that C-section rates among first-time Danish mothers increased during the study period from 12.8% in 1982 to 23% in 2010. "This increase, coupled with better surveillance and detection of adverse or underlying complications earlier in pregnancy, could explain the increased hazard of subsequent stillbirth found in this study among women with a prior cesarean section," they wrote.

Although the findings may be particularly relevant for expectant mothers requesting a non–medically indicated C-section, "it must be acknowledged that a cesarean section can be a vital intervention, and the likelihood of adverse outcome may be decreased, for example, by choosing an elective cesarean section to avoid fetal death due to a failed vaginal birth after cesarean or to prevent sudden stillbirth post-term," the researchers wrote.

The research was supported by the National Perinatal Epidemiology Centre in Cork, Ireland, and as part of the Health Research Board PhD Scholars program in Health Services Research. A coauthor, Dr. Louise C. Kenny, is a Science Foundation Ireland Principal Investigator and director of Centre, INFANT, funded by Science Foundation Ireland.

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