Obesity is an increasing problem in the United States. It is estimated that approximately 31% of white women, 38% of Hispanic women, and 49% of black women in the U.S. are overweight or obese. Many people are aware of the medical problems that obesity can cause (ie, high blood pressure, diabetes, heart attack to name a few), but many are not aware of the reproductive consequences.
Body mass index, or BMI, is an index of a person’s relative “skinniness or heaviness”. BMI factors in a person’s weight and their height to give an overall “index”.
• A standard medical definition of “normal” body weight is a BMI of about 18.5 – 24.9
• A BMI under 18.5 indicates that the person is “underweight”
• A BMI of 25.0 – 29.9 indicates that the individual is “overweight
• A BMI over 30 indicates obesity
• A BMI over 40 indicates morbid obesity
Infertility in obese women is often caused by ovulation problems. Ovulation may be occurring infrequently or not at all. Thus, women may have increasingly irregular, or erratic menstrual cycles or no menstrual cycles at all. However, there is some evidence that this is not the only way that fertility can be affected. Although it is not known for sure, some research suggests that elevated levels of insulin (the hormone that allows the body to use glucose effectively) in overweight and obese women may be another factor which reduces fertility.
Some recently published studies have shown a relationship between BMI and in vitro fertilization success rates. Studies done on women who have undergone IVF have, in general, shown there to be an adverse effect of carrying extra weight on the success of treatment. These studies also indicate a higher risk of early pregnancy loss for overweight or obese women undergoing IVF.
What is known for sure is that obesity increases the risk of many complications of pregnancy, such as preeclampsia, gestational diabetes, and the need for a Cesarean section. These risks increase with increasing BMI. Also, obesity has been linked to an increased risk of birth defects. In addition, there are concerns about the impact that maternal obesity may have on the subsequent development and health of the child.
Women should try to achieve a BMI of …
Men are not immune to the impact of obesity on fertility. The greater the BMI, the higher are the chances of low sperm count and decreased motility (movement) of the sperm. Obese men often have higher than normal estrogen levels. Also, the scrotum remains in closer contact with surrounding tissue, thus raising scrotal temperature and abnormalities with sperm. In addition, there is concern that genetic abnormalities that are associated with obesity can also cause infertility in men.
Long story short…there are many reasons, fertility included, to try to maintain a healthy weight. In contrast to many aspects of infertility that you may not have control over (e.g. decreased ovarian reserve or fallopian tube blockage), you CAN take charge of your general health. It is optimal to achieve a BMI of 19-25 prior to pregnancy; however, even small changes in the right direction can have a large impact. Don’t be discouraged by thinking that you have to achieve a large amount of weight loss all at once – every little bit helps.
If you are wondering what your BMI is, ask your nurse (who can calculate it from your height/weight). Or consider looking on the internet for a ‘BMI calculator’ which will give you the answer. If your number is not where you would like it, consider it a potential aspect of health and fertility that you can take charge of!
If your general health and potential pregnancy health are not strong enough motivators, realize that it takes longer for women who are overweight and/or obese to achieve pregnancy. Obese women may require higher doses of more expensive medications and treatments to get there. You may be able to significantly save on the costs of fertility treatment by getting your weight in a good range.
Certainly, lifestyle changes involving a diet and exercise program are the first-line treatment for obesity. If you have questions about where to start, consider asking your doctor for strategies. For those people with a BMI > 30 who are not achieving results with lifestyle changes alone, some medications may be helpful in enhancing weight loss. For people with a BMI >40, weight loss surgery may be a better and more efficacious option.
Addressing weight issues is never easy. Many folks may have already tried weight loss in the past with mixed results. However, the potential benefits for reproductive health are significant. Now is the time to make changes for a healthier you and a healthier pregnancy!
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