DL: Why is weight gain linked to infertility?

VM: Fat cells produce estrogen, which leads to higher blood levels, interfering with normal feedback signals to the brain. Weight gain can also alter the menstrual cycle, leading to a shorter luteal phase (second half); that means less time for the embryo to implant in the uterus lining. Obesity also lowers an egg’s quality by altering its follicular fluid composition and hormone levels while increasing inflammation. Lower egg quality may lead to greater difficulty in becoming pregnant, a greater risk of early miscarriage, and poorer IVF outcomes.