1. The most dangerous complications of pregnancy, the life-threatening ones, are far more common in obese women.
The two medical complications that are highest risk to the mother are blood clots in the legs that go to the lungs, and a condition called pre-eclampsia. They account for nearly 40 percent of all maternal deaths during pregnancy, and both are much more common in obese women.
Pre-eclampsia, for example, occurs in 5-8% of women overall, but 15-24% of morbidly obese women (those with a Body Mass Index over 40.) And as with many of these risks, there does appear to be a “dose effect:” the more obese you are, the higher the risk. Deaths are still exceedingly rare, but the danger does rise.
2. The risk of stillbirth also triples in morbidly obese women.
Women who are obese tend to have a harder time with conception and are also more likely to miscarry, even if the baby is conceived through IVF. And morbidly obese women are almost three times more likely than non-obese women to have a full-term stillbirth, for reasons that aren’t entirely clear. t may be more difficult to test the babies in obese women, or it could be connected to other medical problems. Women with morbid obesity tend to also have other conditions, from diabetes and high blood pressure to asthma and sleep apnea. Other theories involve the immune system and hormones.
Overall, the risk of unexplained full-term stillbirth is about 1 in 2,000; in morbidly obese women it’s more like 1 in 600.
3.Cesarean sections are not only more common in obese women, but more dangerous.
The overall Cesarean-section rate is about one-third of deliveries; in obese women it’s more like one half.
In an obese woman who has a Cesarean, the risks of complications from anesthesia are much higher because of airway problems. It’s harder to get an epidural in; there tends to be more blood loss and much more infection; and again, obese women are more likely to get blood clots in their legs.