Additionally, this is one of the main reasons that it is more difficult for older women to conceive naturally. When the ovaries of older women develop increasing resistance to fertility hormones, it is much more difficult for the woman to produce multiple follicles . The levels of FSH and E2 help to determine the most ideal dosage and regimen of fertility drugs necessary to achieve an optimal response. An optimal response will result in the production of the maximum number of follicles containing eggs in the ovary. When fewer eggs are available for retrieval, fewer embryos can be transferred back into the woman's uterus.
Older women are more predisposed to miscarriage and birth defects.
Unfortunately, with advanced age, comes an increased incidence of chromosomal aberrations in a woman's eggs. Remember that a woman is producing fewer and fewer eggs as she ages, but additionally, the quality of those eggs deteriorates as well. Chromosomally defective eggs, when fertilized naturally or through the process of IVF, are much less likely to implant into the uterine lining or successfully be carried to term, resulting in miscarriage. Rarely, these aberrant fertilized eggs do implant successfully and the fetus is carried to term, however the result may be a baby with a birth defect such as Down Syndrome. Older women may have other risk factors, in addition to age.