[Analysis of factors affecting vaginal birth after cesarean]

To investigate the factors affecting the vaginal birth after cesarean (VBAC).

Totaly 298 women who underwent trial of labor after cesarean section (TOLAC) from Jan 2015 to Dec 2015 were recruited from Beijing Obstetrics and Gynecology Hospital, FuXing Hospital, Tongzhou Maternal and Child Health Hospital of Beijing, the Second Affiliated Hospital of Chongqing Medical University and the People's Hospital of Chengyang District of Qingdao. The maternal age, the interval from the last cesarean section, the body mass index (BMI) before pregnancy, the weight gain during pregnancy, the way into labor, the Bishop score before labor, the gestational age and the birth weight of the neonate were recorded in a self-made form. The factors affecting VBAC were analyzed by univariate analysis and multivariable logistic regression.

(1)The incidence of VBAC, uterine rupture, postpartum hemorrhage and neonatal asphyxia were 70.5% (210/298), 2.7% (8/298), 9.4% (28/298) and 1.3% (4/298), respectively. No maternal death and perinatal death occurred. (2)The univariate analysis suggested that the maternal age, the BMI before pregnancy, the Bishop score before labor, the labor induction, the gestational age at delivery and the neonatal weight were factors affecting VBAC. The maternal age and the Bishop score before labor were significantly higher in the VBAC group than in the unsuccessful TOLAC group(P<0.05). While the BMI before pregnancy, the induction rate, the gestational weeks at delivery and the birth weight of the neonate were significantly lower in the VBAC group than in the unsuccessful TOLAC group (P<0.05). Multivariable logistic regression analysis showed that successful VBAC was affected by the maternal age, the BMI before pregnancy, the Bishop score before labor and the birth weight of the neonates(P<0.05).

The maternal age, the BMI before pregnancy, the Bishop score before labor and the birth weight of neonate are the main factors affecting VBAC.