Boston, MA A number of studies over the years have found an association between obesity and pregnancy complications, including pre-eclampsia (hypertension), gestational diabetes and stillbirth, but there was little evidence of a direct, cause-and-effect relationship. A new, large-scale study from researchers at the Harvard School of Public Health (HSPH) and the Karolinska Institutet in Stockholm, Sweden, found that an increase in body mass index (BMI) between first and second pregnancies was associated with adverse outcomes, findings that support a possible causal relationship between obesity and pregnancy complications. The results are published in the September 30 edition of The Lancet.
Obesity is a growing problem worldwide. The World Health Organization considers it a major global health threat. In Sweden, during the years of the study (1992-2001), the percentage of pregnant women either overweight or obese increased from 25 percent to 36 percent. 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 researchers, Eduardo Villamor, assistant professor of international nutrition at HSPH and Sven Cnattingius, professor of epidemiology at Karolinska Institutet, looked at a study population of 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 (BMI is weight in kilograms divided by the square of height in meters). The researchers then calculated the difference between BMI at the beginning of the first and second pregnancies. The adverse outcomes that Villamor and Cnattingius 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.
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Contact: Todd Datz
tdatz@hsph.harvard.edu
617-432-3952
Harvard School of Public Health
28-Sep-2006