INTRODUCTION: The objective of this study was to identify medical and pregnancy related risk factors for familial preterm birth.
METHODS: We performed a case-control study comparing demographic, medical and obstetric characteristics between patients with spontaneous idiopathic preterm delivery between 20 and 35 weeks gestation in addition to a prior preterm birth or a first degree relative born prematurely (cases) and patients with only full-term deliveries between 37 and 42 weeks gestation (controls). Consented study participants filled out a comprehensive questionnaire regarding family history, medical and pregnancy complications, which was then validated by review of medical records. Multivariate logistic regression assessed the association of risk factors with familial preterm birth after accounting for co-existent risks.
RESULTS: A total of 211 patients were enrolled, 103 cases and 108 controls. Of familial preterm birth cases, 30% reported bleeding during pregnancy compared to only 5% of controls, adjusted OR 9.0 (95% CI 3.31–24.47). Of the cases that delivered at extremely early gestational ages (20–28 weeks), a higher percentage (44.4%) reported bleeding during pregnancy. Other associated risk factors were prior 1st trimester miscarriage adjOR 2.55 (1.21–5.35) or 2nd trimester miscarriage, adjOR 6.3 (1.76–22.56).
CONCLUSION: Bleeding during pregnancy, as well as prior 1st or 2nd trimester miscarriage were significantly associated with cases of familial preterm birth. Bleeding in pregnancy was more robustly associated with earlier preterm births. These findings warrant further investigation into the association between bleeding and familial preterm birth.
Financial Disclosure: The authors did not report any potential conflicts of interest.
© 2016 by The American College of Obstetricians and Gynecologists. Published by Wolters Kluwer Health, Inc. All rights reserved.