Shoulder dystocia in deliveries of neonates <3500 grams

Objectives To study risk factors for shoulder dystocia (ShD) among women delivering <3500 g newborn.Methods A retrospective case-control study of all term live-singleton deliveries during 2011-2019. Women with neonatal birthweight <3500 g were included. We compared cases of ShD to other deliveries by univariate and multivariable regression.Results There were 79/41 092 (0.19%) cases of ShD among neonates <3500 g. In multivariable regression analysis, the following factors were independently associated with ShD; operative vaginal delivery (odds ratio [OR] 2.78; 95% confidence interval [CI]: 1.28-6.02, P = 0.009), vaginal birth after cesarean (VBAC, OR 2.74; 1.22-6.13, P = 0.010), sonographic abdominal circumference to biparietal diameter ratio (3.73 among ShD vs. 3.62, OR 1.35; 95% CI: 1.12-1.63, P = 0.001) and sonographic abdominal circumference to head circumference ratio (1.036 among ShD vs. 1.011, OR 3.04; 95% CI: 1.006-9.23, P = 0.049).Conclusions There is an association between operative vaginal delivery and ShD also in deliveries <3500 g. Importantly, the proportions between the fetal head and abdominal circumference are a better predictor of ShD than the newborn fetal weight and VBAC is associated with ShD.

Automated summary

The study aimed to investigate the risk factors for shoulder dystocia (ShD) in women delivering newborns weighing less than 3500 g. The results showed that operative vaginal delivery, vaginal birth after cesarean, the ratio of sonographic abdominal circumference to biparietal diameter, and the ratio of sonographic abdominal circumference to head circumference were independently associated with ShD.