FRIDAY, Feb. 3, 2017 (HealthDay News) — It’s not just a woman’s weight that matters when couples are trying to conceive, a new study suggests.
When a woman and her partner are both obese, their chances for pregnancy during any menstrual cycle are about half that of a normal-weight couple, according to the analysis from the U.S. National Institutes of Health.
“It translates to maybe a longer time to get pregnant,” said lead study author Rajeshwari Sundaram. She is a senior investigator at the U.S. National Institute of Child Health and Human Development, a unit of NIH.
Prior studies show an association between female obesity and reduced odds for pregnancy in a single menstrual cycle, as well as a link between men’s increased body weight and lower sperm count, the researchers noted.
This study breaks new ground because it enrolled couples hoping to get pregnant, not couples undergoing fertility treatment. Measurements of body fat were taken before they conceived, and the researchers followed each couple for a year or until a pregnancy occurred.
Lauren Wise, professor of epidemiology at Boston University School of Public Health, said, “This study represents an important contribution to the literature on couples’ body size and fertility.”
Wise, who was not involved in the study, said its strengths include use of more than one measure of body composition and fertility over multiple menstrual cycles. The researchers also controlled for physical activity, a key factor, she added. However, they did not take couples’ diets into account.
The findings, Sundaram said, are representative of reproductive-age couples in the United States.
A total of 501 couples from Michigan and Texas joined the study from 2005 to 2009, as they were ready to try to get pregnant. Infertile couples were excluded. The women ranged in age from 18 to 40 and the men were over 18.
The researchers interviewed each partner to gather data on lifestyle, habits, and medical and reproductive history. Couples completed daily journals on lovemaking, and women recorded their menstrual cycles and pregnancy test results.