Has your doctor told you that you’re not ovulating? That your follicles are not reaching maturity? Have you tried drugs and they haven’t worked? Maybe it’s time to look at something you can control – your weight.

Before we start, let me state that most obese women are not infertile. But many infertile women are overweight or obese.

In 1968 it was estimated that approximately 600,000 women in the US sought help to conceive. It jumped to 900,000 by 1972 and stayed that way through 1980. By 1983 that number doubled to over 2 Million. According to the National Survey of Family Growth, between 2011 and 2015 over 7.5 million women in the US sought out help for infertility.

Notably, obesity and overweight have increased dramatically in reproductive age women since 1983. This correlation is important and should not be overlooked. Not by you or your doctor.

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Evidence shows that obese women, that is women with a BMI of 30 or more are at an increased risk of developing infertility. Overweight and underweight women also have a higher risk than women in a normal BMI range. But their risk is substantially lower than obese women.

PCOS is considered the major cause of not ovulating, but the reviews note that not all obese women have PCOS and not all PCOS women are obese. Yet, they make clear that body weight plays a bigger role than what we believed when it comes to ovulating.

Excess body weight is associated with insulin sensitivity and hyperandrogenism. The most common symptom of hyperandrogenism is excessive terminal hair growth. The thick pigmented hair found on the scalp, beard, armpit and pubic areas. Also known as hirsutism.

The insulin sensitivity and ovarian hyperandrogenism caused by increased body weight seems to be independent of PCOS but causes the same issue as PCOS when it comes to not ovulating.

A study done in 2002, determined that ovulatory infertility in the United States may be caused by low weight (a BMI under 20) and overweight (a BMI greater than or equal to 25).

Researchers at Harvard compared 2,527 women with anovulatory infertility against a group of 46,781 women who had given birth and did not have a history of infertility. What they found was they could determine the risk of anovulatory infertility based on BMI. The results showed that a BMI over 23.9 at age 18 increased the risk factor for ovulatory infertility. The higher the BMI, the higher the risk.

Other studies reported similar results concluding that the risk of not ovulating is slightly increased in women who are overweight and underweight but much higher in obese women. This led researchers to believe obesity interferes with ovarian functions which reduce the ovulation rate.

One of the reasons they give is that sex hormones prefer to accumulate in fat rather than the bloodstream. Therefore, obesity may alter the balance between the availability of estrogens, androgens and circulating sex hormones. This equates to a higher steroid pool than found in normal weight women.

Another reason offered is that increased body mass and adipose tissue cause the release of molecules, known as adipokines. These molecules affect proper signaling and communication for adequate ovulation.

We don’t tend to think of fat as anything but fat, but apparently, it plays a bigger role in how our reproductive system works than we ever thought and needs to be a considering factor in conception for those who struggle.

Ovulatory function and pregnancy rates frequently improve significantly after weight loss in obese anovulatory women. Researchers recommended that young obese women who are not ovulating should reach a BMI of less than 35 before trying to conceive. Older women must weigh the time frame associated with losing weight against declining fertility with advancing age.

The psychological impact of infertility is devastating for many. What if losing weight and eating healthy would allow you to naturally conceive? Ask your doctor. But first, ask your mother or grandmother how many women they knew who could not conceive. Or rather who did not have children. Then ask them how many obese women they went to school with. The small numbers will surprise you compared to how many obese women and how many women who have looked into infertility treatments you know.

The next time you visit your infertility doctor, look at the percentage of overweight women compared to normal weight women sitting in the waiting room. Things start to become clearer about the connection between weight and infertility.

Remember though, not all infertility is ovulatory infertility and not all obese women are infertile. But the incidence of obesity and infertility have jumped dramatically in the past 30 or 40 years. Is it coincidence or is there a correlation? For many, maybe weight loss should be the first step in fertility treatment?

Obesity and anovulatory infertility: A review.
Giviziez CR, Sanchez EG, Approbato MS, Maia MC, Fleury EA, Sasaki RS.
JBRA Assist Reprod. 2016 Dec 1;20(4):240-245. doi: 10.5935/1518-0557.20160046. Review.
PMID: 28050960




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