May 5, 2012 -- Babies conceived with infertility treatment methods are more likely to have certain birth defects than babies who are conceived naturally, according to a study published today in the New England Journal of Medicine.
Australian researchers looked at medical records nearly 300,000 babies born in Australia -- more than 4,000 of whom were conceived through an assisted fertility method -- to see if babies born using the various assisting methods were more likely to have birth defects than babies who were conceived naturally.
Eight percent of the babies conceived through assistance were born with birth defects such as heart, genital, kidney, lung and muscle problems, compared to nearly 6 percent of babies who were conceived naturally, the study found. Those conceived through fertility assistance were also more likely to have cerebral palsy.
More than 6 million women of childbearing age in the U.S. have difficulty getting pregnant or staying pregnant, according to the U.S. Centers for Disease Control and Prevention.
Intracytoplasmic sperm injection (ISI), a so-called assisted reproductive technology in which a single sperm is injected into a removed egg and then transferred back to the uterus was the most common type of method associated with birth defects, the study found. The oral hormone pill commonly known as Clomid also increased the risk for defects.
Nearly five percent of infants are conceived using fertility medication, according to the CDC.
Babies conceived though in vitro fertilization (IVF), which is the most common type of assisted reproductive technology, did not have a higher risk for birth defects. Low-dose hormones also did not raise risk.
An estimated 1 percent of all infants born in the U.S. every year are conceived using assisted reproductive technologies such as IVF and ISI, according to the CDC.
The number of women turning to assisted reproductive methods to help them conceive has skyrocketed over the last decade because more women are waiting until they're older to have their first baby.
The increased risk of birth defects may be more likely caused by the identified infertility rather than the assisted methods used to help women get pregnant, according to Dr. James Goldfarb, director of the Fertility Center at University Hospitals Case Medical Center in Cleveland
"The majority of problems with IVF babies are because the patients undergoing the procedure are more susceptible to the problems rather than because of the IVF," said Goldfarb. "That's encouraging because we can say in the situation that you'll see a 2.5 percent higher chance of birth defects, but that risk could be the same even if done naturally."
Some women who undergo fertility treatments may be older or have reproductive complications that may make pregnancy more difficult.
After five miscarriages, Alicia Cooney, then age 35, and her husband turned to fertility treatments. It started with hormones but the couple soon moved on to ISI and IVF.
"After three years of fertility treatments, there was a lot of anxiety," said Cooney. "We wanted to be parents. There was frustration and anxiety."
Cooney's first round of IVF led to yet another miscarriage. Cooney said she was never told about any potential risks associated with fertility treatments.
While previous studies suggest a slight increase in the risk of birth defects for babies conceived through assisted reproductive technologies, the risk is still extremely low.
"It would've made me a bit nervous to know that," said Cooney.
But then again, she said, she was determined to keep trying.
"I still would've done it," she said.
Now, with two sons 18 months apart, Cooney, 40, of Cleveland, says she is grateful that methods were able to help her stay pregnant.
"I always think about how hard it was to have them and how happy I am to have them," she said.
The risk of complications to a woman undergoing any type of fertility method is also extremely low, said Goldfarb.
The biggest risk to both the mother and infant is the increased chance of having twins or multiple babies, he said.
Babies born in multiple birth situations can be up to 8 times more likely to have a birth defect, including cerebral palsy, he said.
In this study, however, parents who became pregnant with twins or multiple babies had a smaller risk of birth defects than women who became pregnant with only one baby.
The method in which the embryo is prepared also affected whether the babies conceived were at risk for birth defects. In fresh embryo transfers, there was a higher risk of birth defects than using embryos that had been frozen.
Weaker embryos that go through the freezing process are less likely to survive, allowing only the stronger embryos to be implanted back into mother, according to the researchers.
The findings shouldn't discourage women from using fertility methods to help in getting pregnant, said Goldfarb. The chances of pregnancy are different for each woman, and the risks and benefits of fertility methods also varies, he said.
"The fact that the patient has had a problem getting pregnant only slightly increases the risk to having a healthy pregnancy, but going through IVF isn't going to raise that risk any further," he said.