Obese women more likely to have unwanted pregnancies

Tiffany O'Callaghan/ www.time.com

Though they tend to have sex less frequently than their slimmer peers, obese women may be four times more likely to have an unwanted pregnancy, according to findings published in BMJ this week. In a study of more than 12,000 French men and women between the ages of 18 to 69, researchers found that obese women were less likely than healthy weight peers to use oral contraception or seek information on contraception options, and were also more likely to have unplanned pregnancies. Compared with normal weight men, obese men, the study found, were more likely to struggle with erectile dysfunction.

The team of researchers from France and England collected data through nearly hour long telephone interviews conducted in 2006. By asking participants' height and weight, researchers were able to calculate body mass index (BMI). Using World Health Organization classifications, researchers considered individuals with a BMI less than 18.5 underweight, 18.5 to 25 normal weight, 25 to 30 overweight, and higher than 30 obese. (According to estimates from a BMI calculator from the National Heart Lung and Blood Institute for a 5'5" woman: up to 112 lbs. would be underweight; 112 to 150lbs., normal; 150 to 180 lbs. overweight; and over 180 lbs., obese. For a 6'0" man: up to 137 lbs. would be underweight; 137 to 185 lbs., normal; 185 to 220, overweight; and over 200 lbs., obese.)

Of the study population, 63% of women and 54% of men were normal weight, 21% of women and 35% of men were overweight, and 9% of both genders were obese. Researchers noted that, in keeping with previous research, compared with their lower BMI peers, obese respondents were more likely to report suffering from chronic conditions such as diabetes, heart disease and depression. They also found that obese study participants were more likely to have completed fewer years of formal education.

They also noted that, as has been documented elsewhere, for respondents in serious heterosexual relationships, a partner's BMI strongly correlated to one's own. That is, two thirds of obese women and more than one third of obese men gave height and weight measurements for their romantic partners indicating that they too were either obese or overweight.

Yet the ultimate point of the study was to examine how BMI — and associated health issues — might affect sexual health. To that end, researchers found that, compared with normal weight women, obese women were 30% less likely to report having a sexual partner in the previous year, and obese women were half as likely as lower BMI peers to say that sexuality was an important component of their "personal life balance." 

Among women under age 30, researchers noted that obese respondents were four times as likely to report having had an unplanned pregnancy or abortion compared with normal BMI-range peers. They also found that, compared to normal range BMI women, obese women were less likely to have spoken with a doctor in the previous year about options for contraception, were less likely to use the birth control pill or condoms, and were significantly more likely — 8 times more likely, specifically — to report using less effective contraception methods (such as "pulling out").

For both overweight and obese men, the likelihood of confronting sexual dysfunction in the previous year was more than twice that of normal BMI-range peers. Additionally, while rates of sexually transmitted disease did not differ significantly among women based on BMI, obese men were far more likely than normal weight peers to report having a sexually transmitted disease in the previous 5 years. Among 30- to 49-year-old men with more than one sexual partner in the previous year, obese men were less likely to report using condoms.

Given the prevalence of obesity, the findings, the authors say, point to a significant public health problem, and a need to tactfully improve education and outreach. As the authors sum up:

"The scale of the problem and the magnitude of the effects (particularly the fourfold increase in risk of unintended pregnancy among obese women) warrants focused attention. In terms of targeting advice and care, a considerable proportion of the population is obese, is easily identified as such, and is at increased risk in terms of poorer sexual health status."

While obesity and sex may be two of the trickiest topics for doctors to tackle in conversations with patients, in an accompanying editorial, Dr. Sandy Goldbeck-Wood, an obstetrician and gynecologist at Ipswich Hospital in the U.K. and a specialist in psychosocial medicine, argues that it's physicians' duty to confront the issues in spite of any discomfort. What's more, Goldbeck-Wood concludes that there are three principle lessons to be gleaned from the study. First, that clinicians need to pay closer attention to "the complex contraceptive needs of obese women." Second, that they point to the fact that sexual health is a component of the intricate and interwoven relationships between a huge range of mental and physical ailments. And lastly, she concludes, from a public health standpoint:

"The study lends a new slant to a familiar message: that obesity can harm not only health and longevity, but your sex life."