An update of impact of obesity on female infertility and its management

Obesity has a negative effect on reproductive potential due to functional changes in the Hypothalamo-Pituitary-Ovarian (HPO) axis. Obesity is often associated with hyperinsulinemia,a known stimulus for increased androgen production.8 Androgens get converted to oestrogen (Og) in periphery namely in Adipose tissue (AT) present in excess=> negative feedback on the HPO axis and thus affecting gonadotropin production.9 This presents with menstrual abnormalities along with ovulatory dysfunction. Hyperinsulinemia is commonly found to be an aetiopathological factor of PCOS .Obesity contributes to insulin resistance(IR) and exacerbates the symptoms of PCOS with obese women often showing a more severe phenotype.10,11 Increased androgen levels in PCOS=>further accumulation of visceral fat accelerating IR and hyperinsulinemia and thus stimulating more ovarian as well as adrenal androgen production in a perceptual cycle.12 Prevalence of PCOS in some obese populations approaches 30% although causative role of obesity in PCOS development has not been established.13−15 Various studies have shown that obese women take a longer time to conceive. In a Danish cohort of women planning pregnancies showed decrease in fecundity ratios with increasing BMI’s.16,17 Obese women do not conceive despite not having ovulatory dysfunction. On examining a large American cohort of >7000ladies , Law et al showed reduced fecundity in eumenorrheic obese women[18].Further data given from a huge Danish cohort by van den Steer in 3000 ladies with normal cycles, probability of spontaneous conception reduced linearly with each BMI point >29kg/ m2.19 Obesity also affects ART results providing a direct scenario that the pathologies lie beyond the ovulatory disorder .Obese women who undergo IVF have smaller oocytes which are less likely to fertilize normally.20,21 Various studies have shown a negative impact on live birth rates(LBR’s)and this appears to correlate with increasing BMI.21−24 In a review of ART in both overweight and obese women showed a modest impact on LBRs with a pooled odds ratio of 0.90 but in a large study of women with class III obesity(BMI>40KG/m2)there was a 50%reduced probability of live birth.21,25