NYHOMESTUDY BLOG

November 18, 2008

By DENISE GRADY
Infants conceived with techniques commonly used in fertility clinics are two
to four times more likely to have certain birth defects than are infants
conceived naturally, a new study has found.

The findings applied to single births only, not to twins or other multiples.
The defects included heart problems, cleft lip, cleft palate and
abnormalities in the esophagus or rectum. But those conditions are rare to
begin with, generally occurring no more than once in 700 births, so the
overall risk was still low, even after the fertility treatments. Cleft lip,
for instance, typically occurs in 1 in 950 births in the United States, and
the study found that the risk about doubled, to approximately 1 in 425,
among infants conceived with the fertility treatments.

The procedures that increased the risk were so-called assisted reproductive
techniques, like in vitro fertilization, which require doctors and
technicians to work with eggs and sperm outside the body. The study did not
include women who only took fertility drugs and did not have procedures
performed.

“I think it is important for couples to consider the fact that there may be
a risk for birth defects,” said Jennita Reefhuis, an epidemiologist at the
Centers for Disease Control and Prevention, and the first author of the
study, which was published online on Sunday by the journal Human
Reproduction.

But Dr. Reefhuis (pronounced REEF-house) also said that although her study
linked fertility procedures to birth defects, it did not prove the
connection or explain it. If the connection is real, it is not known whether
the procedures increase the risk for birth defects, or whether infertility
itself raises the risk.

Fertility doctors, she said, “may not believe my findings.”

Dr. James A. Grifo, director of the fertility clinic at New York University
Medical Center, said, “The good news is that the risk is low.”

Dr. Grifo said more research was needed to test the findings, because the
study included only 281 women who had fertility procedures. He said that if
the association with birth defects was real, the underlying cause was more
likely related to the patients’ infertility than to the treatments.

“The results are concerning, but with this small a sample of patients, a
bigger study would need to be done,” Dr. Grifo said. “And the fact that they
see it in singletons, not in twins, makes it hard for me to think this is a
direct relationship.”

Twins and other multiple births have a higher risk of birth defects than
single births and whether infertility treatment adds to that risk is
unknown.

Dr. Alan R. Fleischman, vice president and medical director of the March of
Dimes, said: “I think it’s an important study. It’s confirmatory of the
direction we have been concerned about, an increase in some structural birth
defects in babies born with assisted reproductive techniques compared to
those born without such. And yet the numbers are still small, the risks are
low.”

Women considering fertility treatment should be informed that there might be
a risk of birth defects, Dr. Fleischman said, but they need not be “overly
concerned.”

In 2005, about 52,000 infants were born in the United States as a result of
in vitro fertilization and related techniques, according to the disease
centers. The number doubled from 1996 to 2004; currently, about 12 percent
of women ages 15 to 44 in this country seek fertility treatments.

The researchers used information already collected by a large project paid
for by the government, the National Birth Defects Prevention study. Dr.
Reefhuis and her colleagues compared 9,584 women who had children with birth
defects, and 4,792 control women whose children were born without defects.
In the control group, 1.1 percent of the women (51) had undergone fertility
procedures; in those whose children had birth defects, the figure was 2.4
percent (230). The increased risk among those who had the procedures was not
related to their age, income, the number of children they had or to whether
or not their babies were born prematurely.

Dr. Fleischman acknowledged that the number of women who had fertility
procedures was small, but, he said, “These are very well-studied
populations, and they’re just about as good data as we have.”

The study included information from 281 births conceived with fertility
techniques and 14,095 without.