A major national study in Sweden has shown a remarkable 47% reduction in infant mortality and morbidity in pregnancies extending beyond 41 weeks of gestation. This reduction follows changes in induction procedures that have been implemented since 2020. The study highlights the impact of earlier induction on improving the chances of survival and reducing complications for babies born at or after 41 weeks.
Study Background: Pregnancy typically lasts around 40 weeks, but approximately 22% of women experience pregnancies that extend to 41 weeks or longer. Although Sweden has a relatively low risk of stillbirth and early-life death, this risk increases with the duration of the pregnancy beyond 41 weeks. As a result, questions about the appropriate timing for induction have been a point of focus.
Published in PLOS Medicine, the study analyzed registry data from over 150,000 births in Sweden, focusing on those who were at least one week past their expected due date. The researchers aimed to assess how infant mortality and morbidity in late-term pregnancies have changed since 2020 when Swedish maternity hospitals altered their induction practices based on research findings from 2019.
Induction Practice Shift: Prior to 2020, the standard practice was to induce labor at 42 weeks gestation. However, a 2019 study revealed that inducing labor at 41 weeks resulted in fewer infant deaths compared to waiting until 42 weeks. In response, Sweden implemented a more active management approach in 2020, offering induction at 41 weeks or performing individual assessments to determine the need for induction.
Study Findings: The comparison between the periods 2017-2019 and 2020-2023 revealed a significant drop in infant mortality. The number of stillbirths or infants dying within four weeks of birth fell from 124 (1.7 per 1,000 births) in the earlier period to 74 (0.9 per 1,000 births) in the later period, marking a 47% decrease. The study also indicated a reduction in neonatal morbidity in the more recent period, as well as an increase in emergency cesarean sections. Interestingly, cesarean section rates also rose in pregnancies between 39 and 40 weeks, although the increase was more pronounced after 41 weeks.
While the exact factors responsible for the improved survival rates remain unclear, the shift towards routine induction at 41 weeks or intensive monitoring seems to be a significant contributor.
Expert Insights: Karin Källén, Professor of Clinical Epidemiology in Obstetrics and Gynecology at Lund University, emphasized the importance of the findings, noting that the reduction in neonatal death and severe morbidity, coupled with an increase in inductions and emergency cesarean sections, has likely saved around 18 infant lives annually in Sweden.
Ulla-Britt Wennerholm, Adjunct Professor of Obstetrics and Gynecology at Sahlgrenska Academy, University of Gothenburg, highlighted that the study provides strong evidence supporting the active management approach of induction or individual assessment at 41 weeks. However, she also stressed that, while the overall improvement is significant, the absolute risk for individual women and their babies remains low, regardless of whether delivery occurs at 41 or 42 weeks.
Conclusion: This Swedish study provides compelling evidence that altering induction practices to include earlier interventions at 41 weeks gestation has led to a significant reduction in infant mortality and morbidity. Although the exact mechanisms behind this improvement are still under investigation, the findings underscore the benefits of active management in late-term pregnancies. This research not only contributes to the ongoing discourse on pregnancy management but also emphasizes the importance of continuous evaluation and adaptation of clinical practices to enhance maternal and infant health.
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