Fetomaternal Bleeding and Neonatal Hematocrit following Cesarean Delivery: Routine versus Transplacental Transection.

To evaluate fetomaternal bleeding following routine cesarean delivery compared with cesarean delivery involving transplacental transection.  A prospective cohort study evaluating cesarean delivery in which the placenta was transected (cases) versus controls (placenta not transected) from January 2016 to April 2018. A maternal Kleihauer-Betke's (KB) test and newborn hematocrit were performed shortly after delivery.  The rate of a positive KB test was not significantly different between cases (  = 31) and controls (  = 61) (19 vs. 14%; odds ratio [OR]: 1.44; 95% confidence interval [CI]: 0.46-4.49;  = 0.74). Median neonatal hematocrits were not different. However, the rate of newborn hematocrits <40% at delivery was higher in cases compared with controls (23 vs. 3%; OR: 8.90; 95% CI: 1.72-45.90;  = 0.005).  A cesarean requiring transplacental transection to accomplish delivery does not significantly increase the rate of fetomaternal bleeding but is associated with a higher likelihood of newborn hematocrit <40% at delivery.