The association between threatened preterm labour and perinatal outcomes at term: a population-based cohort study
Thursday, February 13, 2020
2:45 PM – 3:00 PM
Location: Max Bell - MB252
Introduction: Exposure to threatened preterm labour (TPTL) with delivery at term has been associated with adverse perinatal outcomes such as lower birth weight, although studies have been limited by sample size. The objective of this study was to estimate the association between TPTL and perinatal outcomes of infants born at term.
Methods: A retrospective cohort study was conducted with data from the Nova Scotia Atlee Perinatal Database on singleton pregnancies delivered at term (≥37 weeks) from 1988 to 2018. Pregnancies with known major fetal anomalies, chromosomal abnormalities, or antepartum hemorrhage were excluded. TPTL was defined in pregnancies with a hospital admission before 37 weeks’ gestation and a code for TPTL with steroids administered or tocolysis. TPTL with term delivery was compared to no TPTL with term delivery using logistic regression, in order to estimate odds ratios (OR) with 95% confidence intervals (CI). Primary outcome measures included birth weight and perinatal mortality and severe morbidity. Institutional REB approval was obtained.
Results: 248,008 term deliveries were included, and of these, 2,237 (0.9%) had TPTL. Women with TPTL were more likely to be ≤ 35 years, multiparous, non-smokers, have previous preterm delivery, and have no other obstetrical complications. The odds of the primary outcomes were higher among those with TPTL relative to those without [birth weight < 2500 g (OR 2.7, CI 2.2-3.3), birth weight < 10th percentile for gestational age (OR 1.5, CI 1.3-1.7), and a composite of severe neonatal morbidity (OR 1.5, CI 1.2-1.8)]. Other outcomes were also associated with TPTL [induction of labour (OR 1.2, CI 1.1-1.3), and 5-minute Apgar ≤7 (OR 1.3, CI 1.02-1.7)].
Conclusion: Although the prevalence of TPTL in term deliveries is low, affected pregnancies are at increased risk for adverse perinatal outcomes. Increased fetal surveillance should be considered in the management of pregnancies affected by TPTL.