A: Doctors have known for some time that being substantially overweight could increase the risk of complications during pregnancy, but less information was known about the consequences of weight gain between pregnancies.

A new study, however, suggests that even modest increases in weight could increase the risk of pregnancy complications. In this study, published in Lancet in September of 2006, researchers compared the first and second pregnancy outcomes in more than 150,000 Swedish women. They found that women who had a higher body mass index (BMI) at the onset of their second pregnancy had an increased risk of pregnancy complications such as pre-eclampsia (hypertension), gestational diabetes and stillbirth. The researchers also noted higher rates of Caesarean deliveries and “large-for-gestational-age” births in these women.

The most surprising part of the study was that even women who were not considered overweight had increased risk of complications with as little as 7 pounds of weight gain between pregnancies. The likelihood of complications appeared to climb as women gained more weight between pregnancies.

This study suggests that all women should try to optimize their weight before becoming pregnant. Even mothers with weight in the normal range could reduce their risk of future pregnancy complications by trying to achieve an optimal weight before their next pregnancy.

For some tips on losing weight postpartum, see my article “Baby, Take it Off: How to Lose Weight after Pregnancy.”