The National Institutes of Health awarded Yale School of Public Health professor Heping Zhang a $7.5 million grant on Sept. 30 — one of the largest grants that Yale researchers have received so far under the federal government’s $787 billion stimulus package — to study infertility treatments.

Zhang’s Data Coordination Center team, which is part of the National Institute of Child Health and Human Development’s Reproductive Medicine Network, will use the grant money to study the drug Letrozole, which the team hopes will lead to a high rate of single births, which result in safer pregnancies.

Most fertility treatments currently on the market lead to multiple pregnancies, which increase the risk of birth defects and premature births. Zhang’s team plans to recruit 900 infertile women at seven clinical sites across the country for their two-year trial, then analyze the data.

Money from the grant, Zhang said, will pay for the Letrozole and the two common fertility drugs, Clomid and gonadotrophins, used in the study. The Investigational Drug Service, which supports clinical studies at Yale-New Haven Medical Center, will package the drugs so that neither doctor nor patient knows which drug each patient receives, said Meizhuo Zhang, the Data Coordination Center’s project director.

The money will also allow Heping Zhang’s team to recruit another staff member.

“Reducing multiple pregnancy rates could significantly reduce maternal and neonatal morbidity and mortality, as well as the cost of health care for these individuals and society,” he said.

About 10 to 15 percent of couples report that they are infertile, said Tracey Thomas SPH ’94, a project manager for the Data Coordination Center. Because infertility is a sensitive issue, Thomas added, many couples are reluctant to seek treatment.

The Reproductive Medicine Network has three other clinical trials in progress funded by a separate NIH grant, Thomas said. It is holding a trial studying the cause of polycystic ovarian syndrome, which causes irregular ovulation and is the leading cause of infertility.

Another trial is testing oxygen levels for embryos conceived by in vitro fertilization. Researchers are also studying whether varicocelectomy, which would fix varicose veins on the scrotum, leads to increased fertility.

The Reproductive Medicine Network was founded in 1989. Participating institutions include the University, the Milton S. Hershey Medical Center at Penn State, University of Pennsylvania, University of Vermont, Wayne State University, University of Michigan at Ann Arbor, University of Colorado at Denver and University of Texas at San Antonio.