Study Links Age to Lab Fertility Success
Monday, January 10th 2005, 11:00 am
News On 6
WASHINGTON (AP) _ The biological clock matters even if a would-be mother uses special reproductive technology. The rate of successful pregnancies using laboratory fertility techniques drops from 37 percent to about 4 percent as women get older, a new study shows.
The study, a sort of report card for the fertility clinic industry, found a dramatic drop in the success rate among older women who went through at least one cycle of assisted reproduction technology (ART).
``Women in their 20s and early 30s who used ART had the most success with pregnancies and single live births. However, success rates declined steadily once a woman reached her mid-30s,'' said Victoria Wright, a heath data analyst and a co-author of an annual report on ART put out by the Centers for Disease Control and Prevention.
``This is a reminder that age remains a primary factor with respect to pregnancy success, and younger women have greater success than older women, even with technology,'' Wright said Friday.
More than 45,000 babies were born in the U.S. through assisted reproduction technology in 2002, an increase of about 5,000 over the 2001 total, according to the CDC annual report. The agency collected data from 391 fertility clinics.
The report is based on results from 115,392 ART cycles that started in 2002 in clinics across the country. ART is a procedure in which both sperm and egg are manipulated to enhance reproduction. An ART cycle is one attempt to monitor, stimulate and harvest eggs with the intent to create embryos that can be transferred into the womb.
Wright said the statistics show a dramatic increase in successful live births from ART. She said there was a per-cycle success rate of about 28 percent in 1996. The rate for 2002, the most recent year with complete data, was 35 percent.
``That's great news for couples using ART,'' said Wright, an analyst for the CDC. ``The technology has improved and more people are using it.''
Wright said that one of the most important findings was the effect of age on success among women who were using their own eggs in the assisted fertility procedures.
Among such women under the age of 35, about 37 percent of the procedures resulted in live births. Among women aged 35 to 37, the success rate dropped to 31 percent, and the rate of success for women aged 38 to 40 was 21 percent and it was 11 percent among women aged 41 to 42. After age 42, success for a woman using her own eggs dropped to four percent.
The report, however, showed that age of the bearing mother had little effect on success if the implanted embryo came from an egg donated by another, usually younger, woman.
``The average live birth per transfer rate (using fresh donor eggs) ... varies only slightly across all age groups. The average live birth per transfer rate is 50 percent,'' the report said. ``In contrast, the live birth rates for cycles using embryos from women's own eggs decline steadily as women get older.''
The most commonly used ART technique involves in vitro fertilization. This means the sperm and egg are united in a laboratory dish and allowed to develop into an embryo which is then either implanted in the birth mother's womb or frozen for future use.
Data in the report suggests that fresh embryos have success rate of about 35 percent, while live births from thawed embryos is about 24 percent.