"We found no statistically significant difference in the overall rates of major and minor malformations or chromosomal abnormalities between newborns in the two groups," says Dr. Tulandi. "Our findings indicate concerns about a link between letrozole and birth defects are unfounded. This is significant because it confirms that letrozole can indeed be used in the treatment of infertility without increasing risk to the fetus."
The study contradicts an earlier, much smaller study linking letrozole to increased rates of inherited malformations. This study led to widespread concern about the use of letrozole, a drug which has been widely used in the treatment of infertility in recent years.
"There were several methodological problems with the earlier study," says Dr. Tulandi. "For one thing, it compared the incidence of birth defects in children conceived spontaneously with that in children conceived through fertility treatments using letrozole. This is an apples-and-oranges comparison, because there are always fewer birth defects in children conceived spontaneously." The earlier study also compared different age groups between the control and treatment.
The new study by Dr. Tulandi, Dr. Robert Casper from Department of Obstetrics and Gynecology at the University of Toronto, and their co-authors examined a total of 911 babies whose mothers were treated for infertility with either letrozole or clomiphene citrate from 2001 to 2005. Five Canadian centres in Quebec and Ontario participated.
This study was funded in part by the McGill Reproductive Center of the MUHC.
About the McGill University Health Centre (MUHC):
The MUHC is a comprehensive academic health institution with an international reputation for excellence in clinical programs, research and teaching. The MUHC is a merger of five teaching hospitals affiliated with the Faculty of Medicine at McGill University -- the Montreal Children's, Montreal General, Royal Victoria, and Montreal Neurological Hospitals, as well as the Montreal Chest Institute. Building on the tradition of medical leadership of the founding hospitals, the goal of the MUHC is to provide patient care based on the most advanced knowledge in the health care field, and to contribute to the development of new knowledge.
About the JGH:
Since 1934, the Sir Mortimer B. Davis - Jewish General Hospital, a McGill University teaching hospital, has provided "Care for All," serving patients from diverse religious, linguistic and cultural backgrounds in Montreal, throughout Quebec and beyond. As one of the province's largest acute-care hospitals, the JGH has achieved a reputation for excellence in key medical specialties by continually expanding and upgrading its facilities for clinical treatment and teaching, as well as research at the Lady Davis Institute for Medical Research. For more, please visit www.jgh.ca.