Submitted by Kate Seldman Sun 05/08/2011
Is obesity linked to infertility? Doctors say yes – and for a variety of reasons.
Polycystic ovarian syndrome, one of the causes of infertility, is linked to weight gain, and also to trouble losing weight. This disorder can cause hormone imbalances, failure to menstruate, irregular periods and lack of ovulation. Around 15% of PCOS sufferers are also overweight or obese.
Obesity can also affect fertility even when a woman has previously had a regular menstrual cycle and no problems ovulating. Studies show that women who have been obese since childhood are more likely to miss their periods or lose them altogether.
The obesity-infertility link may have to do with the pituitary gland: a study of obese mice showed that the body reacts in an interesting way to the high insulin levels often associated with obesity.
The pituitary gland begins responding to these elevated insulin levels by flooding the body with an excess of fertility hormones, which results in infertility. One of these hormones is luteinizing hormone, which, in overabundance, disrupts the ovaries’ ability to release eggs.
Overweight or obese women who take fertility drugs often need larger doses in order for them to work the same way that they would on women of average weight. While average-weight women may take these drugs subcutaneously (under the skin), this may not be possible for obese women: they often need intramuscular injections of the drugs in order for them to be absorbed properly.
Even then, the rate of absorption is frequently poorer than in women of average weight. Other obesity-related disorders, such as high blood pressure and Type 2 diabetes, may negatively affect a woman’s ability to get pregnant.
Doctors often recommend that obese women trying to conceive should take a break and attempt to lose weight before trying again.
This also allows for related disorders to be diagnosed and treated, which may make it more likely for the woman to get pregnant. In stubborn or extreme cases, gastric bypass surgery or bariatric surgery may help a woman lose enough weight so that her menstrual cycle is regulated, and allow her to conceive.
If she has polycystic ovarian syndrome, however, other underlying conditions might also need to be treated before she can get pregnant. Obesity can also affect a man’s fertility: it lowers testosterone, reduces the sex drive, and cuts the amount of sperm produced.