We found that infants whose birth sizes were average had reduced risk of being delivered through cesarean section compared to very small or smaller than average. Many previous studies have also demonstrated that very large babies or small babies are at increased risk of cesarean. In this context, the cesarean section might indicate several pregnancy complications and associated risks with high or low birth weight. For example, a multivariate analysis of the risk factors and obstetric complications associated with macrosomia found out that high birth weight was associated with higher rates of cesarean birth and other pregnant birth complications. Studies have also demonstrated that women who gain excessive weight in the course of the pregnancy have a higher risk of having a very big neonate with a birth weight of over 4,000g or 4,500g, and in turn, they are more likely to need a cesarean section. Furthermore, gestational diabetes during pregnancy may cause mothers to have a large baby or other complications which might increase the chance of having a cesarean.
As with previous findings , we found an increased risk of cesarean birth in overweight and obese women. Overweight and obese women have a higher risk of complications during pregnancy and delivery by affecting uterine contractions during labor, increase the risk of hypertension, pre-eclampsia, gestational diabetes, increase maternal pelvic soft tissue, and cephalopelvic disproportion. Furthermore, children born to overweight and obese mothers are at increased risk of congenital abnormalities, fetal and neonatal death and macrosomia leading to a higher need for caesarean section. In addition, due to the large body volume of overweight and obese women, more time may be needed for oxytocin to reach the optimal tissue level.
Thus the presence of excess intra-abdominal adipose tissue could mechanically obstruct the progression of labor and compromise feto-placental circulation causing fetal distress necessitating caesarean birth.