Genetic influences on preterm birth

Abstract

Adverse pregnancy outcomes, such as PTB, PPROM, placental abruption, and preeclampsia, are common and contribute to spontaneous and medically-indicated preterm deliveries, with acute and long-term complications for both the mother and infant. Etiologies underlying such adverse outcomes are not well understood. As maternal and fetal genetic factors may influence these outcomes, we estimated the magnitude of familial aggregation as one index of possible heritable contributions. Using the Missouri Department of Health’s maternally-linked birth certificate database, we performed a retrospective population-based cohort study of births (1989-1997), designating an individual born from an affected pregnancy as the proband for each outcome studied. We estimated the increased risk to siblings compared to the population risk, using the sibling risk ratio, s, and sibling-sibling odds ratio (sib-sib OR), for the adverse pregnancy outcomes of PTB, PPROM, placental abruption, and preeclampsia. Risk to siblings of an affected individual was elevated above the population prevalence of a given disorder, as indicated by S ( S (95% CI): 4.3 (4.0-4.6), 8.2 (6.5-9.9), 4.0 (2.6-5.3), and 4.5 (4.4-4.8), for PTB, PPROM, placental abruption, and preeclampsia, respectively). Risk to siblings of an affected individual was similarly elevated above that of siblings of unaffected individuals, as indicated by the sib-sib OR (sib-sib OR adjusted for known risk factors † This chapter is adapted from: Plunkett J, et al. (2008) Population-based estimate of sibling risk for adverse pregnancy outcomes. BMC Genetics, 9:44.