Obese Couples Risk Lower Fertility
Study Shows Weight of Both Partners May Affect Conception
March 7, 2007 -- A couple trying to conceive may face an extra challenge when both the man and the woman are overweight or obese, new research suggests.
Compared with normal-weight couples, obese couples participating in a Danish study were almost three times as likely to take more than a year to achieve a pregnancy.
Previous studies have shown that weight can affect fertility in women, but the Danish study is the first to examine the impact of overweight or obesity in couples.
The findings strongly suggest, but do not prove, a causal association between excess weight in both partners and decreased fertility, researcher Cecilia Ramlau-Hansen tells WebMD.
“Because of the study design we cannot say for a fact that it is extra body fat that makes people less fertile, but it certainly appears that this is the case,” she says. “If a couple is overweight and wants to have a child it may be beneficial for both partners to attempt weight loss.”
Weight Loss Reduced Time to Conception
The researchers analyzed data from 47,835 couples who participated in a nationwide study of pregnancy outcomes in Denmark. Women in the study completed four interviews over a period of two years, giving information for both themselves and their partners on weight, height, previous pregnancies, smoking, and socioeconomic status.
The findings are published in the March issue of the journal Human Reproduction.
A total of 8.2% of the women, 6.8% of the men, and 1.4% of the couples in the study were obese, defined as having a body mass index (BMI) of 30 or more. BMI looks at weight in relation to height and is used as an indicator of body fat.
As measured by BMI, a 5-foot-2-inch person who weighs 165 pounds or more is considered obese, as is a 6-foot-tall person who weighs 220 or more.
Just over half of the men and two-thirds of the women in the study were normal weight.
Ramlau-Hansen and colleagues from Denmark’s University of Aarhus evaluated the time it took the couples to become pregnant. Sub-fertility was defined as failure to conceive for at least a year after initiating unprotected sex with the goal of conceiving.