The MOMS trail

Some of the most devastating news a pregnant woman can receive about her unborn child is that it has a birth defect. The most frequently occurring permanently disabling birth defect in the United States is spina bifida, which occurs in about 1.5 to 2 out of every 1,000 live births when the spinal column fails to completely close during the first month of pregnancy.

Vanderbilt University Medical Center is one of three hospitals in the country participating in the randomized, controlled MOMS trial (Management of Myelomeningocele Study) sponsored by the National Institutes of Health. Doctors with experience in fetal surgery from Vanderbilt, The Children’s Hospital of Philadelphia, and the University of California at San Francisco are enrolling 200 women in the study. Half of the babies will receive fetal surgery and half the traditional surgery a few days after birth. They are randomly chosen for one type of surgery or the other and then followed for two and a half years or longer to determine whether infants operated on in utero suffer the same disabilities as those operated on as newborns and whether the results outweigh the risks to both mother and child.

The trial began in 2003 and enrollment is about 60 percent complete, says Ed Yang, M.D., Ph.D., assistant professor of Pediatric Surgery and medical director of the Center for Advanced Maternal-Fetal Care at Vanderbilt. It’s taking longer to enroll women than the study investigators would like, but the outcome will be a clear message on the safety and efficacy of fetal surgical repair, Yang said.

“We think it will take another two to three years to recruit patients, then we’ll have to follow the patients for another two and a half years at a minimum, so this trial could be going on for another five years. It takes incredible institutional commitment to stay with this, and we have that here. We’re looking at 2012 before we’re done and during that time we could be developing newer approaches, advancing the way we do this operation and subselecting different populations within the population we’re studying, but we’re just kind of stuck. It’s incredibly frustrating because we can’t advance in our care beyond this operation.”

Yang said enrollment is slow because of two reasons: the incidence of spina bifida has been declining because of the use of folic acid by pregnant women, and because women have either not heard about the trial or they think it has been completed.

“We’re constantly trying to communicate with the obstetrics community who sees these patients that the trial is still ongoing,” he said. “It’s going to tell us a lot about how the operation works, the risks, benefits, long-term issues of patients and the mom, how the child’s bladder works after fetal surgery versus standard care, etc.”

Since the 1930s the first step in treatment of babies with spina bifida has been surgically closing the opening in their back a few days after birth. The surgery prevents further damage to and infection of the nerve tissues but doesn’t restore function to the already damaged nerves. A shunt is usually placed within the ventricles to drain excess fluid and relieve pressure in the brain.

Research has shown that spinal function in babies with spina bifida seems to worsen throughout pregnancy. It is believed that there is ongoing damage to the open portion of the spinal cord, possibly from contact with amniotic fluid. Because of this research, in 1994, doctors began trying out various methods for closing spina bifida defects in the womb. The fetal surgical procedure is done at 19 to 25 weeks of pregnancy.

Vanderbilt’s fetal surgery team includes several specialties, including ethicists who meet with families during the evaluation process.
- NANCY HUMPHREY