731: The risk of abnormal placentation and hemorrhage in subsequent pregnancy following primary elective caesarean delivery

Abstract

China has the highest caesarean rate in the world largely driven by the overuse of elective caesarean delivery (CD). With termination of the one child policy in 2015, more women are now having a second pregnancy. We aimed to evaluate the relationship between mode of first delivery with subsequent placenta previa, placenta accreta/increta and significant postpartum hemorrhage (PPH). This retrospective cohort study included women with 2 consecutive singleton deliveries between 2007-2017 at our institution if the women were nulliparous and delivered at term at the time of first delivery. The first pregnancy delivery mode was classified as (1) vaginal delivery, (2) antepartum CD without labor, or (3) intrapartum CD after onset of labor. Within these 3 groups, rates of placenta previa, placenta accreta/increta and PPH at the time of the second delivery were compared. Significant PPH was defined as hemorrhage requiring blood transfusion. Logistic regression was used to adjust for maternal characteristics, gestational week, obstetric complications, previous pregnancy loss, history of placenta previa, and the time interval between the two pregnancies. RESULTS: A total of 8 208 women were analyzed. Most first deliveries were vaginal (n=5210, 63.5%), followed by antepartum CD (n=2432, 29.6%) and intrapartum CD (n=566, 6.9%). The incidence of placenta previa in subsequent deliveries differed by previous delivery mode: vaginal, 0.9%; antepartum CD, 2.0%; intrapartum CD,1.6% (P<0.001). Similar differences were also observed with respect to placenta accreta/increta (0.5% vs 1.5% vs 0.9%, P<0.001) and PPH (0.6% vs 1.2% vs 0.4%, P=0.017). Compared to the previous vaginal delivery group, the antepartum CD group had increased risks of placenta previa (aORs 2.02, 95% CI 1.35-3.05), placenta accreta/increta (aOR 2.52; 95% CI 1.53-4.14) and PPH ( aOR 1.78, 95%CI 1.14-2.98) in subsequent pregnancies. However, previous intrapartum CD was not significantly associated with increased risks of these complications. Previous antepartum CD was associated with 2-fold increased risks of placenta previa, placenta accreta/increta and significant PPH in the second delivery compared to women with a prior vaginal delivery. The increased risks of subsequent abnormal placentation following primary antepartum CD may be important for counseling concerning non-medically indicated elective caesarean.View Large Image Figure ViewerDownload Hi-res image Download (PPT)