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Both elective and emergency cesarean sections in first births appear to slightly increase the risk of stillbirth and ectopic pregnancy in subsequent pregnancies, according to a new study.
Compared with women whose first birth was a spontaneous vaginal delivery, primiparous women with a primary C-section were 14% more likely to have a subsequent stillbirth and 9% more likely to have a later ectopic pregnancy, but were no more likely to have a subsequent miscarriage, reported Sinéad O’Neill of Cork University Maternity Hospital, Ireland, and her associates (PLoS Med. 2014 July 1 [doi:10.1371/journal.pmed.1001670]).
The analysis was limited by incomplete data, and the increased rate of stillbirths and/or ectopic pregnancies could be driven by underlying factors that contributed to the need for a C-section, the researchers noted.
They analyzed Danish national registry data on 832,996 primiparous women with a live birth between Jan. 1, 1982, and Dec. 31, 2010, followed until the next stillbirth, miscarriage, ectopic pregnancy, live birth, death or emigration. Miscarriage was defined as loss before 28 weeks’ gestation until April 2004, and before 22 weeks’ gestation from 2004 onward.
The fully-adjusted analysis controlled for the following:
• Maternal age, origin, and marital status.
• Previous stillbirth, miscarriage, or ectopic pregnancy.
• Birth year.
• Socioeconomic status (mother’s education and both parents’ gross income).
• Medical complications in the first live birth, including multiples, diabetes, gestational diabetes, placental abruption, placenta previa, and hypertensive disorders.
• Gestational age at birth and birth weight.
The researchers lacked data on maternal body mass index, smoking status, and fertility treatment, as well as causes of stillbirth, maternally requested C-sections, and the gestational ages of the stillbirths and miscarriages.
The increased rate of stillbirth (hazard ratio 1.14) among women with a primary C-section, compared with women with an initial spontaneous vaginal birth, translated to an absolute risk increase of 0.03% and a number needed to harm of 3,333. Emergency C-sections showed a barely higher risk (HR 1.15), but the risk with elective C-sections (HR 1.11) did not reach statistical significance (95% CI 0.91, 1.35).
"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.
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.
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.
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.
Both elective and emergency cesarean sections in first births appear to slightly increase the risk of stillbirth and ectopic pregnancy in subsequent pregnancies, according to a new study.
Compared with women whose first birth was a spontaneous vaginal delivery, primiparous women with a primary C-section were 14% more likely to have a subsequent stillbirth and 9% more likely to have a later ectopic pregnancy, but were no more likely to have a subsequent miscarriage, reported Sinéad O’Neill of Cork University Maternity Hospital, Ireland, and her associates (PLoS Med. 2014 July 1 [doi:10.1371/journal.pmed.1001670]).
The analysis was limited by incomplete data, and the increased rate of stillbirths and/or ectopic pregnancies could be driven by underlying factors that contributed to the need for a C-section, the researchers noted.
They analyzed Danish national registry data on 832,996 primiparous women with a live birth between Jan. 1, 1982, and Dec. 31, 2010, followed until the next stillbirth, miscarriage, ectopic pregnancy, live birth, death or emigration. Miscarriage was defined as loss before 28 weeks’ gestation until April 2004, and before 22 weeks’ gestation from 2004 onward.
The fully-adjusted analysis controlled for the following:
• Maternal age, origin, and marital status.
• Previous stillbirth, miscarriage, or ectopic pregnancy.
• Birth year.
• Socioeconomic status (mother’s education and both parents’ gross income).
• Medical complications in the first live birth, including multiples, diabetes, gestational diabetes, placental abruption, placenta previa, and hypertensive disorders.
• Gestational age at birth and birth weight.
The researchers lacked data on maternal body mass index, smoking status, and fertility treatment, as well as causes of stillbirth, maternally requested C-sections, and the gestational ages of the stillbirths and miscarriages.
The increased rate of stillbirth (hazard ratio 1.14) among women with a primary C-section, compared with women with an initial spontaneous vaginal birth, translated to an absolute risk increase of 0.03% and a number needed to harm of 3,333. Emergency C-sections showed a barely higher risk (HR 1.15), but the risk with elective C-sections (HR 1.11) did not reach statistical significance (95% CI 0.91, 1.35).
"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.
Both elective and emergency cesarean sections in first births appear to slightly increase the risk of stillbirth and ectopic pregnancy in subsequent pregnancies, according to a new study.
Compared with women whose first birth was a spontaneous vaginal delivery, primiparous women with a primary C-section were 14% more likely to have a subsequent stillbirth and 9% more likely to have a later ectopic pregnancy, but were no more likely to have a subsequent miscarriage, reported Sinéad O’Neill of Cork University Maternity Hospital, Ireland, and her associates (PLoS Med. 2014 July 1 [doi:10.1371/journal.pmed.1001670]).
The analysis was limited by incomplete data, and the increased rate of stillbirths and/or ectopic pregnancies could be driven by underlying factors that contributed to the need for a C-section, the researchers noted.
They analyzed Danish national registry data on 832,996 primiparous women with a live birth between Jan. 1, 1982, and Dec. 31, 2010, followed until the next stillbirth, miscarriage, ectopic pregnancy, live birth, death or emigration. Miscarriage was defined as loss before 28 weeks’ gestation until April 2004, and before 22 weeks’ gestation from 2004 onward.
The fully-adjusted analysis controlled for the following:
• Maternal age, origin, and marital status.
• Previous stillbirth, miscarriage, or ectopic pregnancy.
• Birth year.
• Socioeconomic status (mother’s education and both parents’ gross income).
• Medical complications in the first live birth, including multiples, diabetes, gestational diabetes, placental abruption, placenta previa, and hypertensive disorders.
• Gestational age at birth and birth weight.
The researchers lacked data on maternal body mass index, smoking status, and fertility treatment, as well as causes of stillbirth, maternally requested C-sections, and the gestational ages of the stillbirths and miscarriages.
The increased rate of stillbirth (hazard ratio 1.14) among women with a primary C-section, compared with women with an initial spontaneous vaginal birth, translated to an absolute risk increase of 0.03% and a number needed to harm of 3,333. Emergency C-sections showed a barely higher risk (HR 1.15), but the risk with elective C-sections (HR 1.11) did not reach statistical significance (95% CI 0.91, 1.35).
"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.
FROM PLOS MEDICINE