The effect of maternal and fetal weight on the risk of emergency cesarean section in nulliparous women.

Although many studies based on different ethnic groups have analyzed the impact of maternal and infant weight on overall cesarean section rates in recent years, research on the impact of maternal and infant weight on emergency cesarean section (EmCS) rates is lacking, especially in the Chinese population. This study aimed to analyze whether maternal and fetal weight could influence the risk of EmCS. A total of 8427 nulliparous women who delivered vaginally (full-term, singleton, and cephalic presentation) were included in this study and divided into the normal vaginal delivery (VD) and EmCS groups. Of 8427 cases, 909 (10.8%) were delivered by EmCS because of failed VD. Compared with pregnant women with a normal body mass index, the risk of EmCS in overweight women increased significantly (P < .001). Birth weight > 3550 g was associated with an increased risk of EmCS. Subgroup analyses showed that among women with underweight and normal weight, old age, inadequate gestational weight gain, and large for gestational age were independent high-risk factors for EmCS (P < .05), whereas small for gestational age was the low-risk factor. Compared with the fetal distress group, the weight of newborns in the nonfetal distress group was significantly higher (P < .001), and the main cause of EmCS in women with macrosomia, large for gestational age, or birth weight ≥ 3550 g was fetal distress (P < .05). The prepregnancy maternal and fetal weights can affect the risk of EmCS. Weight management should be enhanced to control gestational weight gain according to the prepregnancy body mass index to reduce the risk of EmCS due to failed VD.