- Previous studies on infertility have focused on the body composition and weight status of female partners.
- But a new study states that the body composition of both male and female partners play an important role in deciding fertility status.
- Study states that obese couples take longer to conceive.
- Fertility specialists therefore should also consider including couples' body composition and weight status when counseling patients.
Couples in which both partners are obese may take longer to achieve pregnancy, compared to their non-obese counterparts.
According to a study by researchers at the National Institutes of Health, obese couples may take anywhere from 55% to 59% longer to conceive.
‘Obese couples may take anywhere from 55%-59% longer time to achieve pregnancy.’
Previous studies on fertility have focused largely on just the female partner's BMI or self-reported height and weight.
"A lot of studies on fertility and body composition have focused on the female partner, but our findings underscore the importance of including both partners," said Rajeshwari Sundaram, Ph.D., a senior investigator in the Division of Intramural Population Health Research at NIH's Eunice Kennedy Shriver National Institute of Child Health and Human Development.
The current study did not focus on those undergoing treatment for infertility. It focuses on couples in the general population .
"Our results also indicate that fertility specialists may want to consider couples' body compositions when counseling patients." Sundaram adds.
The couples in the study were part of the Longitudinal Investigation of Fertility and the Environment (LIFE) Study, which examined the relationship between fertility and exposure to environmental chemicals.
The study enrolled 501 couples from Michigan and Texas from 2005 to 2009.
The ages of women ranged from 18 to 44 years and the men were over 18 years old.
Women kept journals to record their monthly menstrual cycles, intercourse and the results of home pregnancy tests.
The researchers followed the couples until pregnancy or for up to one year of trying to conceive.
Researchers also calculated body mass index (BMI) for each participant, and divided the obese couples into two subgroups:
- obese class I with a BMI from 30 to 34.9
- most obese group, obese class II with a BMI of 35 or greater
The researchers compared the average time among couples in non- obese group (84 men and 228 women), to achieve a pregnancy, to that of the couples in the obese class II group (75 men and 69 women).
The researchers used a statistical measure called the fecundability odds ratio (FOR) to calculate the probability that a couple would achieve pregnancy.
The FOR estimates the couples' probability of pregnancy each menstrual cycle while trying for pregnancy, relative to their BMIs.
Findings show that:
- couples in class II took much longer to achieve pregnancy compared to non-obese couples
- couples in the non-obese group had a FOR of 1
- couples in obese class II had a FOR of .45, which indicated that they took 55% longer to achieve pregnancy than their normal weight counterparts
After adjusting for other factors such as age, smoking status, physical activity level and cholesterol level that are known to influence fertility, the ratio for obese class II couples dropped to .41. This indicated that they took 59% longer time to achieve pregnancy.
The authors concluded that the chances of fertility may be reduced by couples' obesity.
They recommend that fertility specialists should consider couples' weight status and body composition when counseling them about achieving pregnancy.
The health benefits of a healthy weight reduces risk of other diseases such as Type 2 diabetes, heart disease and cancer. In addition, taking steps to lose weight may help reduce the time needed to conceive.
The findings appear online in Human Reproduction
- Rajeshwari Sundaram et al. Couples' body composition and time-to-pregnancy. Human Reproduction; (2017) doi:10.1093/humrep/dex001