Overweight and Pregnancy

Today the World Health Organization considers obesity and pregnancy complications as one of the serious global health threat. Though there is little evidence of a direct, cause-and-effect relationship between these two health problems, a number of studies have established a correlation between these two and pre-eclampsia (hypertension), gestational diabetes and stillbirth. Findings of a new study conducted in Sweeden and U.S.A. suggests that an increase in body mass index (BMI) between first and second pregnancies could have negative outcomes, a proposition that support a possible causal relationship between these two problems. In Sweeden the percentage of pregnant women either overweight or obese increased from 25 percent to 36 percent during 1992-2001. In the U.S., the prevalence of obesity in women aged 20-39 years jumped from 9 percent in 1960-1962 to 28 percent in 1999-2000

The study surveyed more than 150,000 Swedish women having their first and second births between 1992 and 2001. They calculated BMI at the first prenatal visit of each pregnancy. The researchers then examined the difference between BMI at the beginning of the first and second pregnancies. The adverse outcomes that the study looked at during the second pregnancy included maternal complications, such as pre-eclampsia, gestational diabetes gestational hypertension and caesarean delivery, and perinatal complications, such as stillbirth and large-for-gestational-age birth. The results showed that weight gain between first and second pregnancies was associated with an increased risk of all these overweight and obesity-related negative outcomes. A gain of one to two BMI units increased the risk of gestational diabetes gestational hypertension or large-for-gestational age birth an average of 20 to 40 percent.

September 9th · Comment(11)

A gain of three or more BMI units showed a 63 percent greater chance of stillbirth compared to a gain of less than one BMI unit and also a greater effect on all other complications. Additionally, the study found that the risk of adverse outcomes increased even in women who were not overweight, but who gained a modest amount of weight between pregnancies. For instance, if a woman who was 5 ft., 5 in., tall and weighed 139 lbs. (giving her a BMI of 23, not considered overweight) gained 6.6 lbs. (1 BMI unit) between her first and second pregnancies, her average risk of gestational diabetes

would increase by more than 30 percent. If she gained 12.2 pounds (2 BMI units), her risk would increase 100 percent. The risk would continue if she gained more weight and became obese.Earlier studies had looked at the risk of pregnancy complications in relation to a single isolated examination of pre-pregnant weight, and found that obesity appeared to increase the frequency of such complications. In this study, we went further back in time to look at how women arrived at that pre-pregnant weight. It turns out that women do not need to become overweight or obese in order to increase their chances of having poor gestational outcomes; only a relatively modest increase in weight between pregnancies could lead to serious complications. In addition, weight loss in overweight women appeared to lower their risk of pregnancy complications. However, it is not possible to differentiate whether weight gain between pregnancies could have been due to lack of weight loss after the first pregnancy, excessive weight gain during initial pregnancy or a weight increase between the time after the first delivery and the next conception. There is also the possibility that other factors or illnesses could be associated with both weight gain and adverse pregnancy outcomes. It is possible that breastfeeding could be one such factor, since women who breastfeed retain less weight post partum while breastfeeding for longer periods of time lowers diabetes risk. But overall, there is a strong evidence that weight gain before pregnancy could lead to a number of pregnancy complications.