(RxWiki News) Advances in fertility medicine have been a blessing for parents who struggled to have children on their own. But one hitch has been a higher rate of birth defects among test tube babies.
A large recent study has found an increased rate of birth defects among babies born through assisted reproduction, though different types of assisted reproduction had different higher rates of congenital problems.
"Discuss the risks of any fertility treatment with your doctor."
Michael Davies, PhD, an associate professor at the University of Adelaide's Robinson Institute and School of Paediatrics and Reproductive Health in Australia, led the study to delineate the various rates of birth defects associated with different methods of reproductive help.
Past studies had already shown a higher rate of birth defects among babies who were born with the help of fertility treatments, but researchers did not know the reasons for the higher rates or whether those rates differed across different treatments.
Davies' team compared the incidence of birth defects for pregnancies among women who had received assisted reproduction treatment; women who became pregnant without assistance but who had previously had a child using reproductive assistance; women who had struggled with infertility problems but never received assistance; and women who had no record of infertility.
The researchers compared data from the records of 6,163 assisted reproduction births in South Australia and data from a national registry of 308,974 births in Australia.
They looked at any major birth defects occurring in a child up until the age of 5, including heart, spinal and urinary tract problems as well as outward physical problems like deformed limbs or a cleft palate.
Without adjusting for any other factors, Davies' team found that 8.3 percent of the pregnancies involving assisted conception had birth defects compared to 5.8 percent of pregnancies without assisted reproduction.
This rate difference means test tube babies are almost 1.5 times more likely to have a birth defect, though this rate drops to 1.28 after the researchers adjusted their calculations to account for other factors that could be influencing the birth defect rate.
When the researchers looked at individual types of reproductive technology, they found the unadjusted rate of defects for in vitro fertilization (IVF) to be 1.26, but this number dropped to 1.07 after accounting for other parental factors. Therefore, IVF alone does not appear to relate to any significantly higher rate of defects.
However, the type of reproductive method called intracytoplasmic sperm injection (ICSI), where sperm is injected into an egg, did have a higher rate of birth defects even after accounting for other characteristics of the parents. These babies were 1.57 times more likely to have birth defects.
The researchers also found a higher rate of birth defects among babies born to women who had struggled with fertility issues, regardless of whether the mother became pregnant with reproductive help or not.
And women who used the drug clomiphene citrate to stimulate their bodies to ovulate had three times the likelihood of having a baby with birth defects. This jump particularly concerned the researchers, said Davies, because the drug is widely available at a low cost and is used by women at their homes, away from a doctor's office.
"While factors associated with the causes of infertility explained the excess risk associated with IVF, the increased risk for a number of other treatments could not readily be explained by patient factors," Davies said. "ICSI, for instance, had a 57 percent increase in the odds of major defect, although the absolute size of the risk remained relatively small."
This means that the rate of birth defects among babies born with ICSI was significantly larger than the rate of defects among babies born without reproductive help, but the actual number of increased babies born with defects was fairly small.
Further, if an embryo was frozen before being used with ICSI, the risk of birth defects dropped, possibly because embryos that are already developmentally stunted cannot survive the process of being frozen and thawed and so only those embryos that are already strong make it, Davies suggested.
Because the babies studied in this research were born from 1986 to 2002, Davies said further research should be done since treatments have changed so much in the past ten years.
Approximately 3.7 million babies are born every year with assisted reproduction and the technologies of the field and the options to couples are rapidly evolving. Treatment tends to be very inexpensive and is not generally covered by health insurance.
Each attempt of IVF can range from $10,000 to $12,000, plus an additional $2000 if the sperm needs to be injected into the egg through ICSI. The procedures are invasive and the experience tends to be very emotional for couples.
The study was published online May 5 in the New England Journal of Medicine and was presented at the World Congress on Building Consensus in Gynecology, Infertility and Perinatology in Barcelona, Spain.