What maternal factor increases the risk of shoulder dystocia during childbirth?

The increased risk of shoulder dystocia during childbirth is notably associated with gestational diabetes mellitus (GDM). This condition can lead to macrosomia, where the newborn grows larger than average due to excess glucose in the maternal blood affecting fetal growth. Larger babies are more likely to encounter difficulties during delivery, such as shoulder dystocia, because their shoulders may become stuck behind the mother's pubic bone during the birthing process.

GDM increases the likelihood of complications related to fetal size and presentation. So, when the mother's blood sugar levels are not well managed, the risk of having a baby that is too big for safe passage through the birth canal rises significantly. This connection makes understanding and managing GDM essential for reducing complications like shoulder dystocia during labor and delivery.

Other factors, such as maternal age over 35 years or a normal prepregnancy BMI, do not have the same direct impact on shoulder dystocia as gestational diabetes, emphasizing the unique risks posed by metabolic conditions during pregnancy.