Recurring complications in second pregnancy.

OBJECTIVE: To clarify the obstetric consequences in a second pregnancy after a first singleton pregnancy complicated by spontaneous preterm delivery or preeclampsia and stratified by the variation in fetal growth.

METHODS: In a registry-based cohort study, we identified women having a first and second singleton delivery in Denmark from 1978 to 2007 (n=536,419). The exposures and endpoints were preterm delivery, preeclampsia, fetal growth, placental abruption, and stillbirth after 20 weeks of gestation. We used chi and t test to compare differences between incidences on first and second pregnancies.

RESULTS: Compared with a spontaneous first delivery at term, a delivery between 32 and 36 weeks of gestation increased the risk of preterm delivery in the second pregnancy from 2.7% to 14.7% (odds ratio [OR] 6.12, 95% confidence interval [CI] 5.84-6.42) and the risk of preeclampsia from 1.1% to 1.8% (OR 1.60, 95% CI 1.41-1.81); a delivery before 28 weeks increased the risk of a second preterm delivery to 26.0% (OR 13.1, 95% CI 10.8-15.9) and a second pregnancy with preeclampsia to 3.2% (OR 2.96, 95% CI 1.80-4.88). A first delivery in preeclamptic women between 32 and 36 weeks, compared with delivery after 37 weeks, increased the risk of preeclampsia in a second pregnancy from 14.1% to 25.3% (OR 2.08, 95% CI 1.87-2.31) and a small for gestational age infant from 3.1% to 9.6% (OR 2.82, 95% CI 2.38-3.35). Compared with the mean, fetal growth 2 to 3 standard deviations below mean in the first pregnancy increased the risk of preeclampsia from 1.1% to 1.8% (OR 1.62, 95% CI 1.34-1.96) in the second pregnancy.

CONCLUSION: Spontaneous preterm delivery, preeclampsia, and fetal growth deviation tend to recur and predispose to each other in a second pregnancy. Severe complications further increase these risks.

LEVEL OF EVIDENCE: II.