Least microtransfusion from mother to fetus in elective cesarean delivery

Objective: To examine the variability of maternal-fetal microtransfusion in different modes of delivery, as measured by hepatitis B surface antigen (HBsAg) and placental alkaline phosphatase. Methods: We recruited 97 HBsAg-positive pregnant women. The mode of delivery included elective cesarean in 16, normal spontaneous vaginal delivery in 56, vacuum or forceps delivery in 12, and emergency cesarean after labor in 13. We measured HBsAg and placental alkaline phosphatase levels in 97 pairs of maternal and fetal blood samples collected at delivery. Results: The mean maternal placental alkaline phosphatase levels did not differ among these four groups. The mean cord placental alkaline phosphatase level of the elective cesarean group was the lowest (P < .05). All samples of cord sera for this group were negative for HBsAg, compared with 38 of 56, eight of 12, and seven of 13 in the spontaneous vaginal, vacuum or forceps, and emergency cesarean groups, respectively (P < .05). Conclusion: The level of mother-to-fetus microtransfusion was least in the elective cesarean group, as revealed by both the lowest cord placental alkaline phosphatase and HBsAg levels. These observations may have implications for reducing perinatal transmission of blood-borne viruses.