Birth Defects and Fertility Treatment

Two studies focusing on birth defects and fertility treatment techniques recently have been published. The finding of both studies show that certain fertility treatments are associated with increased risks of birth defects, but neither study revealed why this association occurs.

In a meta-analysis of 46 studies, the number of birth defects in children conceived using in vitro fertilization (IVF) was compared with the number of birth defects in children conceived without any intervention.¹ Researchers identified more than 124,000 children conceived via IVF or intracytoplasmic sperm injection (ICSI). These children were 37% more likely to have a birth defect than children conceived naturally.

There are several theories about why birth defects are more likely to occur with fertility treatments. One is that the same reasons that a couple is infertile are the reasons that lead to an increased risk of having a child with a birth defect. Another explanation is that IVF techniques or the drugs involved with fertility treatment may cause a birth defect. A third theory is that infants born as a result of fertility treatment are monitored more closely than those conceived naturally, and any increase in risk is because of this closer monitoring.

Another study conducted in Australia used a birth registry with data on 308,974 births, of which 6163 births involved some form of fertility treatment.² The risk of any birth defect was 8.3% when assisted reproduction technologies were involved, compared with a risk of 5.8% for naturally occurring pregnancies. When IVF was used, the risk of birth defects was 7.2%. The risk increased to 9.9% when ICSI was used. The children of women who used clomiphene to stimulate ovulation were 3 times more likely to have a birth defect than the children of women with no record of infertility. In addition, any history of infertility, even if spontaneous conception occurred, was significantly associated with birth defects.

According to lead researcher Michael Davies, PhD, MPH, a limitation of this study is that the most recent data used is 10 years old, a necessity to ensure a 5-year follow-up for all births. He suggests that risk of birth defects may be lower today, since treatments have evolved and pregnancy rates involving ICSI have improved.

Pertinent Points:

- In reality, there is only a 2.5% greater risk of birth defects when using fertility treatments.

- After adjustment for parental factors, the increased risk of birth defects associated with IVF was no longer statistically significant.²

- Every pregnancy, whether spontaneous or assisted, involves some risk.

References:

References
1. Wen J, Jiang J, Ding C, et al. Birth defects in children conceived by in vitro fertilization and intracytoplasmic sperm injection: a meta-analysis. Fertil Steril. April 3, 2012. [Epub ahead of print.]
2. Davies MJ, Moore VM, Willson KJ, et al. Reproductive technologies and the risk of birth defects. N Engl J Med. 2012;366:1803-1813.