Preterm uterine contractions ultimately delivered at term: safe but not out of danger

Abstract

Objectives: Patients with pregnancies complicated with premature uterine contractions (PMC), but delivered at term are considered as false preterm labor (PTL), and represent a common obstetric complication. We aimed to assess obstetric and neonatal outcomes of pregnancies complicated with PMC, but delivered at term, as compared to term normal pregnancies.

Study design: Obstetric, maternal and neonatal outcomes of singleton pregnancies complicated with PMC between 24-33(6)/7 weeks (PMC group), necessitating hospitalization and treatment with tocolytics and/or steroids, during 2009-2014, were reviewed. The study group included only cases who eventually delivered ≥37 weeks, which were compared to a control group of subsequent term singleton deliveries who had not experienced PMC during pregnancy. Neonatal adverse composite outcome included: phototherapy, RDS, sepsis, blood transfusion, cerebral injury, NICU admission.

Results: The PMC group (n=497) was characterized by higher rates of nulliparity (p=0.002), infertility treatments (p=0.02), and polyhydramnios (p<0.001), as compared to controls (n=497). Labor was characterized by higher rates of instrumental deliveries (p=0.03), non-reassuring fetal heart rate tracings (p<0.001) prolonged third stage of labor (p=0.04), and increased rate of post-partum maternal anemia (Hb<8g/dL) p=0.004, in the PMC group as compared to controls. Neonates in the PMC groups had lower birth weights compared to controls, 3149g±429 vs. 3318g±1.1, p<0.001, respectively. By logistic regression analysis, PMC during pregnancy was independently associated with neonatal birth-weight <3rd percentile (adjusted OR 4.6, 95% CI 1.5-13.7).

Conclusions: Pregnancies complicated with PMC, even-though delivered at term, entail adverse obstetric and neonatal outcomes, and may warrant continued high risk follow up.

Keywords: Preterm uterine contractions; Small for gestational age; Term.