“Obesity can increase estrogen production, which can prevent an embryo from attaching to the uterine wall.Comstock/Thinkstock
If you’re a fan of the NBC weight loss show, "The Biggest Loser," you may remember season 11 winner Olivia Ward stating that she joined the competition with the express purpose of improving her chances of becoming pregnant. She had been diagnosed with polycystic ovary syndrome (PCOS), a cause of female infertility that’s more common in obese women, and was told by a doctor that she wouldn’t be able to get pregnant if she didn’t lose weight [source: Prevention]. She was 261 pounds (118.4 kilograms) at the time; she went on to lose nearly half her weight while on the show.
Of course, not everyone can relate to being on national television, but chances are plenty of people can identify with Ward’s plight. You see, nearly 34 percent of American adults are obese [source: Centers for Disease Control and Prevention]. And obesity — which means a person’s actual weight is more than 20 percent higher than his or her recommended weight — is a risk factor for infertility in both women and men [sources: Boyles; Levine].
So it’s clear that being heavy can inhibit your fertility. And while you probably won’t take Ward’s path of shedding weight on camera, you might consider making diet and nutrition changes if your goal is to get pregnant.
To learn more about the relationship between weight and fertility, keep reading.
- Is there a link between obesity and infertility?
- Why Preconception Weight Is Important for Fertility
- Why Being Too Skinny Is Worse for Fertility Than Being Obese
- His and Hers Tips to Maximize Fertility
Is there a link between obesity and infertility?
On the previous page, we brought up the connection between obesity and infertility. That’s because there’s a growing mountain of evidence linking the two.
For example, research shows that spontaneous pregnancy (pregnancy without fertility treatments) becomes less likely the higher a woman’s body mass index (BMI) is more than 29 [source: Science Daily]. In particular, severely obese women are 43 percent less likely to get pregnant than women who are of average weight or simply overweight (but not obese) [source: Boyles].
And it’s not just women whose fertility is influenced by weight. Men, too, can experience reproductive challenges due to obesity. A Danish study found that men with a BMI over 25 had around 22 percent lower sperm concentration and 24 percent lower sperm count than men of normal weight [source: WebMD].
Interestingly, the study examining female fertility noticed problems primarily in obese women (BMI over 30); whereas the study observing male fertility sees trouble starting when the BMI is around 25, which is considered overweight but not yet obese.
While such results may be confusing, the best lesson to be taken from them is — overweight or obese — both partners should consider losing weight, if necessary, to increase the odds of conception.
To learn more about how weight affects fertility, head to the next section.
Weigh Your Options
If you’re in your 20s and obese, you should definitely lose weight to improve your chances of getting pregnant. But if you’re over age 35 and ready to start a family, experts recommend working to conceive as soon as possible. You can still try to lose weight as well; just don’t put off trying to get pregnant while doing so [source: FitPregnancy].
Why Preconception Weight Is Important for Fertility
We’ve pointed out that obesity can hinder your odds of getting pregnant. But you might be wondering how exactly preconception weight affects your fertility. Medical scientists, too, are still trying to find specific answers to this question. The issue is complex and still being actively investigated by researchers, but experts do have insight into a couple of ways obesity impacts fertility:
- PCOS: As previously mentioned, PCOS, or polycystic ovary syndrome, is more common in obese women. This endocrine disorder occurs when a woman’s ovaries produce higher-than-normal amounts of male hormones (all women have a certain amount of male hormones in their bodies, just as all men have a degree of female hormones), and prevents the ovaries from producing fully mature eggs.
- Excess estrogen: Obesity can increase estrogen production in both men and women. In men, too much estrogen can inhibit sperm production [source: University of Utah]. In women, it can prevent an embryo from attaching to the uterine wall [source: WebMD].
Of course, these are ways in which obesity effects fertility. But did you know that being underweight can also have a major impact on your ability to get pregnant? We’ll look at that particular problem on the next page.
Why Being Too Skinny Is Worse for Fertility Than Being Obese
Celebrity news reporter Giuliana Rancic famously publicized her infertility struggles on her reality TV show. And in an interview with Barbara Walters, she admitted that her doctor told her to gain weight to improve her chances of becoming pregnant [source: Glines].
As it so happens, very thin women like Rancic tend to have more trouble conceiving than obese women do. A recent study examined three groups of women seeking in vitro fertilization (IVF) procedures: very thin, normal weight and obese. The normal-weight women had a 50 percent success rate with IVF, obese women had 45 percent and thin women had only 34 percent [source: Macrae].
Low bodyweight can also prevent a woman from conceiving naturally. One possible reason for this is that being underweight can lead to amenorrhea, the absence of menstrual periods [source: Mayo Clinic]. If you’re experiencing amenorrhea, you’re not ovulating. Thin women may also have irregular periods, which can lead to inconsistent ovulation.
A man who’s too thin can be infertile as well. Just as being overweight can reduce a man’s sperm count, so can being underweight [source: Levine].
So don’t think you’re off scot-free just because you’re not overweight or obese. If you’re having a difficult time conceiving and either you or your partner has a body mass index (BMI) under 18.5, you should consider a healthy weight-gain regimen recommended by a dietitian or physical trainer.
For more tips on improving your fertility, click on the next page.
Not sure whether or not you’re obese? According to the Centers for Disease Control and Prevention, the Body Mass Index (BMI) ratings will reveal if you’re underweight (below 18.5), normal (18.5-24.9), overweight (25-29.9) or obese (30 and above). Attention, gamers: That’s one high score you don’t want to hit.
His and Hers Tips to Maximize Fertility
So, by this point you know two important steps to improving your fertility: If you’re obese, lose weight; if you’re underweight, gain it. But, obviously, that’s not all. If weight were the only factor influencing a couple’s ability to conceive, the world would have fewer fertility clinics and lots more babies.
Fortunately, there are other things you can do to increase your chances of getting pregnant. In addition to weight management, both men and women should:
- Improve nutrition
- Manage stress
- Quit smoking
- Cut back on alcohol and caffeine
- Reduce exposure to environmental toxins
- Get regular checkups
In addition,women should avoid vigorous physical activity when trying to get pregnant. Going overboard with exercise can reduce progesterone production and interfere with ovulation [source: Mayo Clinic]. To a lesser degree, excessive exercise can impact a man’s fertility by reducing testosterone levels [source: Levine]. Of course, moderate physical exercise is allowed for both sexes — even recommended.
While men should follow the same general guidelines as women, there are a few differences to keep in mind. For example, abstaining from sex for more than a few days can affect a man’s sperm quality. And certain male-specific health conditions, like low testosterone and variococeles (varicose veins in the testicles), should be addressed by a doctor so that they don’t interfere with conception. As for the boxers vs. briefs debate: There’s no scientific answer to that question, but educated guesses land on the side of boxers [source: Levine].
If you’d like to learn more about fertility, check out the resources in our next section.
Lots More Information
- 10 Common Myths About Getting Pregnant
- 8 Surprising Fertility Facts
- Does stress affect fertility?
- Boyles, Salynn. "Obesity Linked to Infertility in Women." WebMD. Dec. 11, 2007. (June 6, 2012) http://www.webmd.com/infertility-and-reproduction/news/20071211/obesity-linked-to-infertility-in-women
- Centers for Disease Control and Prevention. "About BMI for Adults." Sept. 13, 2011. (June 6, 2012) http://www.cdc.gov/healthyweight/assessing/bmi/adult_bmi/index.html
- Centers for Disease Control and Prevention. "Overweight and Obesity." Nov. 17, 2011. (June 6, 2012) http://www.cdc.gov/nchs/fastats/overwt.htm
- Fertility Authority. "’The Biggest Loser’ Olivia Ward Loses PCOS, Gains Fertility." (June 6, 2012) http://www.fertilityauthority.com/articles/biggest-loser-olivia-ward-loses-pcos-gains-fertility
- FitPregnancy. "Preconception Weight Loss." (June 6, 2012) http://www.fitpregnancy.com/fertility-conception/preconception-weight-loss
- Glines, Carole. "Giuliana Rancic Shares Her Fertility Struggles on ‘The View’." Feb. 25, 2010. (June 6, 2012) http://www.okmagazine.com/news/giuliana-rancic-shares-her-fertility-struggles-view
- Levine, Deb. "Boxers or Briefs: Myths and Facts about Men’s Infertility." WebMD. 1999. (June 6, 2012) http://www.webmd.com/infertility-and-reproduction/guide/male-infertility-facts
- Macrae, Fiona. "Being too skinny damages fertility more than obesity." Daily Mail. Oct. 21, 2011. (June 6, 2012) http://www.dailymail.co.uk/health/article-2051512/Being-skinny-damages-fertility-obesity.html
- MayoClinic. "Amenorrhea-Causes." May 17, 2011. (June 6, 2012) http://www.mayoclinic.com/health/amenorrhea/DS00581/DSECTION=causes
- MayoClinic. "Female fertility: Why lifestyle choices count." May 5, 2012. (June 6, 2012) http://www.mayoclinic.com/health/female-fertility/MY01095/NSECTIONGROUP=2
- MedlinePlus. "Polycystic Ovary Syndrome." (June 6, 2012) http://www.nlm.nih.gov/medlineplus/polycysticovarysyndrome.html
- Prevention. "Biggest Loser Olivia Ward: "An Amazing Woman"." Nov. 2011. (June 6, 2012) http://www.prevention.com/weight-loss/biggest-loser/biggest-loser-weight-loss-success-story-olivia-ward
- ScienceDaily. "Obesity Reduces Chances Of Spontaneous Pregnancy In Women Who Are Subfertile But Ovulating Normally."Dec. 11, 2007. (June 6, 2012) http://www.sciencedaily.com/releases/2007/12/071211233947.htm
- University of Utah. "Aromatase Inhibitors in the Treatment of Male Infertility." Nov. 2011. (June 6, 2012) http://clinicaltrialsfeeds.org/clinical-trials/show/NCT00440180
- WebMD. "Estrogen Affects Fertility Window." Feb. 10, 2003. (June 6, 2012) http://www.webmd.com/infertility-and-reproduction/news/20030210/estrogen-affects-fertility-window
- WebMD. "Obesity Takes Toll on Sperm and Fertility." Oct. 22, 2004. (June 6, 2012) http://www.webmd.com/infertility-and-reproduction/news/20041022/obesity-takes-toll-on-sperm-fertility
- WomensHealth.gov. "Polycystic ovary syndrome (PCOS) fact sheet." Mar. 17, 2010. (June 6, 2012) http://womenshealth.gov/publications/our-publications/fact-sheet/polycystic-ovary-syndrome.cfm