A groundbreaking study of nearly 250,000 U.S. women reveals live birth rates approaching natural fertility can be achieved using assisted reproductive technology, where eggs are removed from a woman's ovaries, combined with sperm and then returned to the woman's body.
The research, led by Michigan State University's Barbara Luke and published in the New England Journal of Medicine, highlights what factors help or hinder getting pregnant using assisted reproductive technology, or ART. The results indicate that when there are favorable patient and embryo characteristics, live birth rates with ART can approach those of natural fertility.
"This is good news for women who are trying to have a child," said Luke, a researcher in the College of Human Medicine's Department of Obstetrics, Gynecology and Reproductive Biology.
The number of ART treatments has more than doubled in the past 10 years, and live birth rates traditionally have been reported per cycle, or per one course of treatment. While that is easily calculated and is the method used by national registries across the world, Luke's team sought to estimate cumulative success rates with continued treatment.
"Women and families want to know the overall chances they will get pregnant, not necessarily whether they will get pregnant during a specific cycle," Luke said.
Data were obtained from the Society for Assisted Reproductive Technology's Clinic Outcome Reporting System for women undergoing treatment between 2004 and 2009. The system contains data on more than 90 percent of all clinics performing ART treatments in the United States.
The study of 246,740 women revealed 57 percent of women achieved a live birth via ART treatment, and 30 percent of all ART cycles resulted in a live birth. Success rates declined with increasing age for women using their own eggs, especially for those ages 38 years and older, but not for women using donor eggs.
The estimated natural fertility rate of the general population is about 20 percent per month, and estimated rates of conceiving spontaneously are 45 percent, 65 percent and 85 percent after three, six and 12 months, respectively.
The study looked at factors such as patient age, diagnosis, response to treatment, cryopreservation and the stage at which embryos were transferred. Two major factors that influence ART success are favorable patient characteristics (specifically age) and good embryo quality. Among older women, live birth rates can be substantially improved with continued treatment and a change to donor eggs.
"Although the decision to use donor eggs is a very personal one, these analyses provide information regarding the likelihood of a live birth using this option," said Luke.
These results also could guide regulations governing health insurance coverage for infertility treatment. The number of treatment cycles covered by insurance is typically limited to two or three. The findings demonstrate that when using a woman's own eggs, the success rates continue to rise beyond two to three cycles; additionally, the study may help providers and women decide when it is appropriate to change to donor eggs.
The study team was made up of researchers from MSU, University of Michigan, Redshift Technologies in New York, Baylor College of Medicine in Houston, Cornell Medical Center in New York, Columbia University Medical Center in New York, Spectrum Health Medical Group in Grand Rapids and Dartmouth-Hitchcock Medical Center at Dartmouth College in New Hampshire.
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