The longer a pregnancy continues past 37 weeks gestation, the higher the risk of a stillbirth, according to a new meta-analysis published this week in PLOS Medicine by Shakila Thangaratinam of Queen Mary University of London, UK, and colleagues.
Of the 3000 babies stillborn every year in the UK, a third appeared healthy at 37 weeks. In the new work, researchers searched major electronic databases for studies on term pregnancies that included weekly numbers of stillbirths or neonatal deaths. Thirteen studies, providing data on 15 million pregnancies and 17,830 stillbirths, were identified and included in their analysis.
The risk of stillbirth increased with gestational age from 0.11 stillbirths per 1000 pregnancies at 37 weeks (95% CI 0.07 to 0.15) to 3.18 stillbirths per 1000 pregnancies at 42 weeks (95% CI 1.84 to 4.35). From 40 to 41 weeks, there was a 64% increase in the risk of stillbirth. Neonatal mortality remained steady in babies born from 38 to 41 weeks, but was significantly higher for babies born at 42 weeks compared to 41 weeks (RR 1.87, 95% CI 1.07 to 2.86, p=0.012).
"Any mother considering prolongation of pregnancy beyond 37 weeks should be informed of the additional small but significantly increased risks of stillbirths with advancing gestation," the authors say. "There is a need to assess the acceptability of early delivery at term to parents and healthcare providers to avoid the small risk of stillbirth. Better stratification of apparently low risk women for complications using individualized prediction models could reduce the number of women who need to be delivered to avoid one additional stillbirth."
The authors received no specific funding for this work.
The authors have declared that no competing interests exist.
Muglu J, Rather H, Arroyo-Manzano D, Bhattacharya S, Balchin I, Khalil A, et al. (2019) Risks of stillbirth and neonatal death with advancing gestation at term: A systematic review and meta-analysis of cohort studies of 15 million pregnancies. PLoS Med 16(7): e1002838. https:/
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Women's and Sexual Health Division, University Hospital Lewisham, Lewisham and Greenwich NHS Trust, London, United Kingdom
Women's Division, North Middlesex University Hospital, London, United Kingdom
Clinical Biostatistics Unit, Hospital Ramon y Cajal (IRYCIS) and CIBER Epidemiology and Public Health (CIBERESP), Madrid, Spain
Dugald Baird Centre for Research on Women's Health, Aberdeen Maternity Hospital, University of Aberdeen, Aberdeen, United Kingdom
University of Malaya, Kuala Lumpur, Malaysia
Fetal Medicine Unit, St George's University Hospitals NHS Foundation Trust, London, United Kingdom
Molecular and Clinical Sciences Research Institute, St George's University of London, London, United Kingdom
Barts Research Centre for Women's Health, Women's Health Research Unit, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, United Kingdom
Multidisciplinary Evidence Synthesis Hub, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, United Kingdom
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