Many studies have highlighted the link between obesity and infertility in women. For example, obesity can contribute to problems with ovulation and to irregular menstrual periods. It also contributes to a lowered response to fertility treatment and to miscarriages. Research indicates that reducing obesity improves women’s reproductive health.
The obesity was defined by World Health Organization as body mass index (BMI) ≥30 kg/m. Obese woman are three times more likely to suffer infertility than women with a normal body mass index (BMI). A Dutch study monitored the effect of obesity upon fecundity in a donor insemination program; 500 women were prospectively monitored. The researchers concluded that the increase in weight led to a decrease in probability of conception per cycle.
Women who are overweight or obese are much less likely to conceive.
Excess weight affects female fertility
A fine hormonal balance regulates the menstrual cycle. Overweight and obese women have higher levels of a hormone called leptin, which is produced in fatty tissue. This can disrupt the hormone balance and lead to reduced fertility. The quantity and distribution of body fat affect the menstrual cycle through a range of hormonal mechanisms. The more excess weight and the more abdominal fat, the greater the risk of fertility difficulties. Many women who carry excess weight still ovulate, but it appears the quality of the eggs they produce is reduced.
Among women who ovulate, each unit of BMI above 29 reduces the chance of achieving a pregnancy within 12 months by about 4%.
Moreover, anovulatory cycles and endometriosis are the main causes of female infertility. The most frequent anovulatory cycles are related to polycystic ovary syndrome (PCOS) occurrence, commonly associated with obesity and hormonal disturbances in the course of obesity. Women with PCOS, face a higher risk of both obesity and infertility. Lifestyle changes, such as losing weight, can trigger body changes that facilitate conception in women with PCOS.
In conclusion, obesity is suggested to have a negative impact on the dynamics of ovulatory hormones, quality of oocyte and thickness of endometrium; and therefore, may reduce fertility. So, nurses and nutritionist should be included in programs that could help the infertile women reduce their weight for a higher chance of ovulation. Extra research should focus on the role of weight reduction on ovulation and health educational programs should be created to raise awareness about the negative impact of obesity on ovulation and fertility.
The good news
While the facts about obesity and fertility can seem daunting, there is some good news too. Weight-loss interventions, particularly those that include both diet and exercise, can promote menstrual cycle regularity and improve the chance of pregnancy. In obese women with anovulatory infertility, even a modest weight loss of 5-10% improves fertility and the chance of conceiving.
- Food and Your Hormones. Applied Functional Nutrition Course (2019) https://thenutrition.academy/wp-content/uploads/2019/09/AFN-Reading-3.3.pdf
- Can obesity & overweight affect fertility? (2016) https://www.nichd.nih.gov/health/topics/obesity/conditioninfo/FAQs_fertility
- The Effect of Obesity on Ovulation; A Prospective Study on Females Seeking Fertility in Beni-Suef, Egypt (2016) http://article.sapub.org/10.5923.j.nursing.20160603.01.html
- How does being overweight affect my fertility? (2018) https://theconversation.com/how-does-being-overweight-affect-my-fertility-95224
- The Nutrition Academy, Applied Functional Nutrition Course, Module 3: Food and your Hormones
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