Being Heavy and Chances of Pregnancy

Being heavy through the hips can make you less likely to become pregnant

There is an ongoing study on young black women (Black Women’s Health Study) who are obese or heavy through the hips to see how likely they are to become pregnant. Your likelihood of becoming pregnant is called fecundity

The women in the study were adjusted for age, education, smoking history, alcohol intake, physical activity, parity (the number of full term deliveries), region, and waist-to-hip ratio.

A large waist-to-hip ratio also was significantly associated with lower fecundity, or longer time to pregnancy (TTP).

“Overall and central adiposity (tummy fat) are associated with reduced fecundability in black women,” Lauren Wise, Sc.D., said at the annual meeting of the Society for Pediatric and Perinatal Epidemiologic Research.

Little is known about the determinants of fertility in black women, who are disproportionately affected by the obesity epidemic in the United States. Studies of central adiposity and fertility in whites have been inconclusive, with some suggesting that adiposity (being obese) may interfere with estrogen (hormone) metabolism, increase insulin resistance (increasing your risk for diabetes), and change the quality (as to whether thick or thin) and pH (acid level) of the mucus of the cervix, said Dr. Wise of the Slone Epidemiology Center at Boston University.

The ongoing Black Women’s Health Study is looking at about 60,000 women is the largest study of U.S. black women’s health yet conducted, and now in its 17th year of follow-up. A total of 15,500 women completed a Web-based survey in 2011 reporting the TTP for each planned pregnancy. There were 10,000 births, of which only 4,000 births (4 out of every 10 pregnancies) were planned. The researchers excluded both the unplanned pregnancies and women who had incomplete data, a history of infertility, and age older than 40 years either in 1995 or while they attempted pregnancy.

The average age was 34 years for all body mass index(BMI, a measure of obesity) groups including those classified as overweight (BMI, 25-29 kg/m2), obese (BMI, 30-34) and very obese (BMI, 35 or greater).

Dr. Wise and her colleagues also stated that a higher BMI was associated with less education and less vigorous exercise, and vice versa; and was also positively associated with waist-to-hip ratio, waist circumference, and current smoking status.

After adjusting for all previous possible variabilities plus BMI, researchers found that a waist circumference of 33-35 inches – but not beyond – was significantly associated with lower fecundity.

Fecundity was not lower in women who were underweight (BMI less than 18.5).

During a discussion of the results, one attendee pointed out that asking participants about marital status, which the investigators did, is not the same as asking about relationship status or frequency of intercourse.

Another audience member observed that male obesity is proving to be just as important as female obesity in terms of a couple’s inability to conceive.

Indeed, a recent review involving 14 studies and about 10,000 men reported that overweight and obese men are at increased risk of sperm count abnormalities(oligozoospermia or azoospermia), compared with normal-weight men (Arch. Intern. Med. 2012;172:440-2).

Possible explanations for this relationship include several mechanisms that lead to increased temperature around the scrotum; and accumulation of toxins and liposoluble endocrine (hormone) disruptors in fatty tissue.

The analysis and the Black Women’s Health Study are sponsored by the National Institutes of Health. Dr. Wise and her coauthors reported no disclosures.

Leave a Reply