Fact or myth?

3. The risk of spontaneous preterm birth is higher in obese than non-obese women.

Myth

Obese women have a greater likelihood of indicated preterm birth -- early delivery for a medical reason, such as maternal diabetes or high blood pressure. But, paradoxically, the risk of spontaneous preterm birth -- when a woman goes into labor for an unknown reason -- is actually 20 percent lower in obese than non-obese women. There is no established explanation for why this is the case, but Thornburg says current thinking suggests that this is probably related to hormone changes in obese women that may decrease the risk of spontaneous preterm birth.

Fact or myth?

4. Respiratory disease in obesity -- including asthma and obstructive sleep apnea -- increases the risk for non-pulmonary pregnancy complications, such as cesarean delivery and preeclampsia (high blood pressure).

Fact

Obese women have increased rates of respiratory complications, and up to 30 percent experience an exacerbation of their asthma during pregnancy, a risk almost one-and-a-half times more than non-obese women. According to Thornburg, respiratory complications represent just one piece of the puzzle that adds to poor health in obesity, which increases the likelihood of problems in pregnancy. She stresses the importance of getting asthma and any other respiratory conditions under control before getting pregnant.

Fact or myth?

5. Breastfeeding rates are high among obese women.

Myth

Breastfeeding rates are poor among obese women, with only 80 percent initiating and less than 50 percent continuing beyond six months, even though it is associated with less postpartum weight retention and should be encouraged as it benefits the health of mom and baby.

Thornburg acknowledges that it can be challenging for obese women to breast feed. It often takes longer for their milk to come in and they can have lower production (breast size has nothing to do with the amount of milk produced). Indicated preterm birth can result in prolonged separations of mom and baby as infants are admitted to the neonatal intensive care unit or NICU. This, coupled with the higher rate of maternal complications and cesarean delivery -- up to 50 percent in some studies -- in obese women, can make it harder to successfully breast feed.

"Because of these challenges, mothers need to be educated, motivated and work with their doctors, nurses and lactation professionals to give breast feeding their best shot. Even if you can only do partial breastfeeding, that is still better than no breastfeeding at all," says Thornburg.