Recurrence of Gestational Age in Sibships: Implications for Perinatal Mortality

• Published in: American journal of epidemiology 1999-10, Vol.150 (7), p.756-762
• Main Authors: Melve, Kari Klungsøyr, Skjærven, Rolv, Gjessing, Hakon K., Øyen, Nina
• Format: Article
• Language: English
• Subjects: Adult; Biological and medical sciences; Birth Order; Diseases of mother, fetus and pregnancy; Female; Gestational Age; Gynecology. Andrology. Obstetrics; Humans; infant; Infant Mortality; Infant, Newborn; Infant, Premature; Medical sciences; Norway - epidemiology; Nuclear Family; Pregnancy; Pregnancy. Fetus. Placenta; premature; Registries; Risk Factors; sibling relations
• ISSN: 0002-9262; 1476-6256
• DOI: 10.1093/oxfordjournals.aje.a010078

The authors Studied the extent to which preterm birth and parinatal mortality are dependent on the gestational ages of previous births within sibships. The study was based on data collected by the Medical Birth Registry of Norway from 1967 to 1995. Newborns were linked to their mothers through Norway's unique personal identification number, yielding 429, 554 pairs of mothers and first and second singleton newborns with gestational ages of 22–46 weeks, based on menstrual dats. Siblings' gestational ages were significantly correlated (r = 0.26). The risk of having a preterm second birth was nearly 10 times higher among motherswhose firstborn child had been delivered before 32 weeks gestation than among mothers whose first child had been born at 40 weeks, Howeve, parintatl mortality in preterm second births was slgnificantly higher among mothers whose first infant had been born at term, comparted with mothers whose firstborn child wasdelivered at 32–37 weeks. Since parinatal mortality among preterm infants is dependent on the geational age in the mother's previous birth, a common threshold of 37 weels' gestation for defining preterm birth as a risk factor for perinatal death may not be appropriate for all births to all mothers. Am J Epidemiol 1999; 150: 756-62.