Placental complications in subsequent pregnancies after prior cesarean section performed in the first versus second stage of labor

Objective: To examine whether prior cesarean delivery (CD) in the first stage of labor (non-progressive labor in the first stage - NPL1), when compared with CD in the second stage of labor (non-progressive labor in the second stage - NPL2), is associated with different rates of third stage placental complications in the subsequent delivery.

Methods: A retrospective cohort study, of all deliveries following a CD due to NLP1 or NLP2 that occurred between the years 1988 and 2013, was undertaken. Multiple gestation pregnancies, known uterine malformations or uterine fibroids were excluded. Rates of third stage complications (retained placenta, adherent/increta/percreta placenta, manual removal of the placenta) were compared between the groups. Univariate analysis was followed by multivariate analysis.

Results: During the study period, there were 3828 subsequent deliveries of parturients who were operated due to NPL1 and NPL2 (72.91 and 27.09%, respectively). Rates of manual removal of the placenta as well as adherent placenta were significantly higher among parturients following CD due to NPL2 (28.4 versus 24.0%, p = .04, 1.2 versus 0.4% p < .01, respectively). In a multivariate analysis controlling for possible confounders, adherent placenta was found to be independently associated with vaginal delivery following CD due to NPL2 (odds ratio 2.98, 95% confidence interval 1.30-6.77).

Conclusions: Prior CD due to NPL2 as opposed to NPL1 is independently associated with adherent placenta in the subsequent delivery. A higher index of suspicion may be needed when evaluating these women during pregnancy as well as during management of the delivery.