Menopause occurs when a woman stops menstruating, or having her period. During monthly menstruation, a woman’s body prepares for the possibility of pregnancy. In response to different hormones, the lining of the uterus thickens and a follicle in one of the ovaries begins to mature. As the follicle matures, an egg develops inside. The follicle ruptures and the egg leaves the ovary and travels through one of the fallopian tubes to the uterus.

If the egg is fertilized by sperm and attaches itself to the uterine wall, a woman becomes pregnant. If the egg is not fertilized or does not attach itself to the uterine wall, the thickened uterine wall is shed though the process of menstruation. When a woman has not experienced menstruation for 12 months in a row with no underlying cause, menopause is diagnosed.

Menopause is a natural biologic process and most women experience it between the ages of 45 and 55. Some women experience menopause before the age of 40, a condition known as premature menopause or premature ovarian failure (POF). About one in every 1,000 women between the ages of 15-29 and one in every 100 women between the ages of 30-39 are affected by POF. In the US, it is estimated that 250,000 to one million women experience POF.

Oftentimes, the cause of POF is unknown. In some cases, a cause can be determined, such as chemotherapy or radiation treatment for cancer. Women with POF experience the same symptoms as a woman entering menopause, including decreased fertility. In fact, only 6%-8% of women with POF become pregnant.

Previous animal studies have shown that by transplanting ovarian tissue, it is possible to restore ovarian function and fertility. In a case report published online June 7, 2005 in the New England Journal of Medicine doctors describe their successful attempt to restore fertility to a 24-year-old woman with POF using an ovarian tissue transplant from her twin sister.

About the Study

The women in the report were 24-year-old identical (monozygotic) twins. One sister had three naturally conceived children; the other sister had been diagnosed with POF at age 14. At 23, the sisters attempted two unsuccessful cycles of in vitro fertilization (IVF). Although mature eggs were retrieved from the fertile sister and embryos were transferred to the sister with POF, pregnancy was not established.

For the ovarian tissue transplant, the fertile sister had one ovary surgically removed. Tissue from the outer portion of the ovary (where the eggs are found) was removed and divided into thirds. Surgeons placed one third of the tissue on each ovary in the sister with POF and one third was preserved for future use if necessary. Both sisters were home one day after surgery.

The fact that identical twins were involved in this case meant that the sister who received the new ovarian tissue did not need to take drugs to suppress her immune system and prevent a rejection of the foreign tissue. These so called immunosuppressive drugs would have been toxic to a developing embryo, drastically lowering the chances of a successful pregnancy. Since the two sisters were a perfect genetic match, no rejection occurred.

The Findings

At 71 days after the surgery, the sister with POF had a maturing follicle in one ovary. At 80 days, she experienced her first period in more than 10 years. Her second menstrual cycle occurred 142 days post transplant. On day 176, an ultrasonographic exam showed a normal pregnancy, and at 38 weeks, the sister gave birth to a healthy baby girl.

How Does This Affect You?

Although the results of this report are exciting, it is only a single case. Ovarian transplantation is still experimental. Although this procedure was successful, it took place between identical twins. Solving the rejection problem in all other types of donors will be challenging. The authors note that “ovarian transplantation between monozygotic twins will be rare.”

The fact that the physicians were able to restore fertility and that a successful pregnancy was achieved will likely ensure that more experimental procedures like this will be attempted. One possible application of this technology is for women undergoing chemotherapy or radiation therapy. Many pre-menopausal women are forced to make the choice between life-saving cancer treatments and the premature loss of fertility. In the near future, women may be able to have ovarian tissue removed and stored before cancer treatments begin, with the hope of restoring fertility after they are cured or in long-term remission.