Older women (particularly over the age of 35) have a gradually increasing risk of pregnancies which are genetically abnormal. Most of these genetically abnormal pregnancies are miscarried in the first or second trimester of pregnancy. Unfortunately, older women (again older than 35 and especially past the age of 40) have a higher risk of miscarrying even genetically normal pregnancies. Several studies have found that for women over 40, the overall risk of miscarrying a pregnancy is about 75%.

Assisted reproductive technology--using "fertility drugs" in conjunction with artificial insemination or in vitro fertilization--may enhance an older woman's ability to conceive. Using injectable (or, in some cases, oral) medications, a woman can increase the number of available oocytes which mature and are then available for fertilization. With artificial or "intrauterine" insemination, a doctor can insert sperm directly into the uterus and time it according to when the oocytes are mature.

Although the overall pregnancy rate achieved with medications and insemination is around 14-17%, the success rate falls to less than 10% for women over 40. With in vitro fertilization (also known as IVF), a woman uses injectable hormones to stimulate her ovaries after which a doctor extracts the mature oocytes using a minimally invasive procedure. In the lab, the extracted oocytes are mixed with sperm or even directly injected with individual sperm.

If embryos develop from this in vitro fertilization process, they are then transferred into the woman's uterus. The pregnancy success rate for IVF can be as high as 50-70% in women in their 20s or early 30s and though the success rate declines with age, some centers achieve success rates over 20% for women in their early 40s.