For women seeking to become pregnant with the help of assisted reproductive techniques such as In-vitro fertilization, reasonable pregnancy rates of at least 5 percent per cycle are obtainable through the end of the 43rd year, researchers at Harvard Medical School have found.

After that, they report, the rate of live births is low - no higher than 2.3 percent.

Based on the findings, Dr. Sigal Klipstein and her colleagues recommend that women between the ages of 40 and 43 “should be provided with this one last opportunity for attaining a pregnancy.”

Nearly 20 percent of all women using assisted reproduction are 40 years old or older. Because women in their 40s are approaching the end of their reproductive years, team notes in their report in the medical journal Fertility and Sterility, “they are perhaps the ones most in need of informative, data-driven counseling.”

To derive this information, the Boston-based researchers analyzed outcomes for women between 40 and 48.8 years old who underwent assisted fertilization at Boston IVF in Waltham, Massachusetts, between 1999 and 2002. The study included 1263 women who underwent a total of 2705 assisted-reproduction cycles.

The rate of live births per cycle for women who were 40 was 13.9 percent. For women ages 41, 42, or 43, the rates did not differ significantly (9.7 percent, 9.2 percent and 7.6 percent respectively), the team found.

Thereafter, however, pregnancy rates declined rapidly. Rates were 2.6 percent for those who were 44 years old, 1.9 percent for those who were 45 and 0 percent for women 46 or older.

Moreover, “while the rare pregnancy will occur in women aged 44 years or older,” the risk of having a child with a chromosomal defect such as Down’s syndrome “is so profound as to limit all efforts for success in this age group,” the researchers add.

In women younger than 45, an increase in the number of embryos transferred was associated with an increased live birth rate, Klipstein and colleagues report. None of the women over age 42 delivered triplets or higher order multiple births.

The investigators therefore recommend considering the transfer of all available embryos beginning at 42 years of age, “except for in those rare robust responders.”

After age 43, they advise, other options should be considered, such as egg donation and adoption.

SOURCE: Fertility and Sterility, August 2005.