Obesity is associated with infertility in women through multiple and complex mechanisms. One of the leading causes of infertility is obesity among women of reproductive age. The prevalence of obesity and overweight is increasing rapidly making it a worldwide pandemic.
Obesity has detrimental influences on all systems, including reproductive health. The prevalence of obesity in infertile women is high, and it is well known that there is an association between obesity and infertility. Overweight women have a higher incidence of menstrual dysfunction and anovulation. Overweight and obese women are at high risk for reproductive health. The risk of subfecundity and infertility, conception rates, miscarriage rates, and pregnancy complications are increased in these women. They have poor reproductive outcomes in natural as well as assisted conception. These poor reproductive outcomes include assisted reproduction such as ovulation induction, in vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI), and ovum donation cycles. Weight loss has beneficial effects on the reproductive outcomes in these patients.
Obesity brings out many problems such as social, psychological, demographic, and health problems. It is related to increased health risks such as diabetes mellitus, hypertension, coronary heart disease, and osteoarthritis and is linked to various malignancies, particularly endometrium, breast, and colon cancers. Obesity also plays a significant role in reproductive disorders, particularly in women. It is associated with anovulation, menstrual disorders, infertility, difficulties in assisted reproduction, miscarriage, and adverse pregnancy outcomes.
Because of lower implantation and pregnancy rates, higher miscarriage rates, and increased maternal and fetal complications during pregnancy, obese women have a lower chance to give birth to a healthy newborn.
Some endocrine disorders such as PCOS, hypothyroidism, and insulin resistance are more common in overweight women and it is known that the rates of miscarriage are increased in these disorders. Although PCOS is closely associated with obesity, it appears that obesity may also cause miscarriages alone.
Obesity and infertility
Infertility is the lack of pregnancy despite regular unprotected sexual intercourse after a year or therapeutic donor insemination in women less than 35 years of age and after 6 months in women 35 years and older. It is one of the most frequent disorders of the reproductive system in developing countries. Although many obese multiparous women are able to get pregnant despite their obesity, there is an increased prevalence of infertility in obese women. Dr Shchukin has found that a larger portion of women who are seeking medical help to get pregnant are obese. The studies demonstrated that the duration required to achieve a spontaneous pregnancy rate is increased and pregnancy rates are decreased in obese women, including regular ovulatory obese women. In several studies, it is found that the risk of infertility is threefold higher in obese women than in non-obese women and their fertility seems to be impaired in both natural and assisted conception cycles. The association between obesity and the lower fertility rate has been shown in several studies, and it has been shown that obesity in early adulthood alters the reproductive functions. The risk of menstrual problems and infertility increased in these women. Obesity causes infertility through various pathways, including impaired ovarian follicular development, qualitative and quantitative development of the oocyte, fertilization, embryo development, and implantation.
Obesity and assisted conception
Because of the obesity epidemic worldwide and its association with infertility, a large number of overweight and obese women are treated using ART. Obese infertile women who undergo ART face some difficulties during the treatment. Several studies have shown that the ovarian response to controlled ovarian stimulation in obese women undergoing IVF is low. The other adverse outcomes of ovarian stimulation in obese women are reduced oocyte retrieval, poor quality of oocyte and embryo, decreased intrafollicular human chorionic gonadotrophins concentration, decreased peak estradiol levels, decreased number of mature oocytes,
In conclusion, recent studies and meta-analyses have shown that obesity has adverse effects on assisted reproductive technology, including ovulation induction and IVF/ICSI treatments. Obesity reduces pregnancy rates, live birth rates, and increases the miscarriage rates in treatment cycles.
Obesity and treatment in infertility
It is difficult to treat anovulatory infertility in obese women because, as mentioned above, the obese women have a lower chance of conception following ART as they require a higher dosage of gonadotropin, respond poorly to ovarian stimulation, and have a higher risk of miscarriage.
Weight loss among overweight and obese women has been shown to improve reproductive outcomes, including fertility. Clark et al. found that even a small weight loss in anovulatory obese infertile women resulted in improvements in ovulation, pregnancy rate, and pregnancy outcome.
Weight loss should be primarily offered to anovulatory overweight and obese women. It is important to determine which patients will benefit from weight loss and the interval between the weight loss and the initiation of an ART programme. However, if weight loss will continue for a long time, the patient can enter into a catabolic phase of fertility because advanced age is one of the most deteriorating factors in infertility.
Furthermore, most overweight and obese women have a partner that is also overweight or obese, and overweight men also have been shown to be a risk factor for a prolonged time to achieve pregnancy. It is shown in a study that weight loss of these men significantly increased the total sperm count and percentage of sperm with normal morphology.
Overweight and obese patients should be informed about the importance of pre-pregnancy weight reduction and should be encouraged to lose weight before the treatment to reduce poor obstetrical outcomes due to obesity.
Although weight loss is the gold standard of treatment in women with a high BMI, ART treatment should not be delayed too much because of increasing age. Many fertility centres have a protocol to initiate ART treatment; however, there are no evidence-based guidelines regarding fertility treatment in overweight and obese infertile women.