Women who get pregnant through in vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI) have a higher risk of stillbirth, scientists have found, although the overall risk is still low.
Researchers from Aarhus University Hospital in Denmark studied 20,000 single pregnancies and found a four-fold increased risk of stillbirths for women who had IVF or ICSI compared with women who conceived naturally.
"The results from our study emphasize the need for continuous follow-up of the outcome of fertility treatments so that the information given to infertile couples seeking treatment can be differentiated to their individual circumstances," Kirsten Wisborg, who led the study, wrote in the Human Reproduction journal Wednesday.
She added, however, that the risk of stillbirth was still very low for IVF and ICSI pregnancies. The rate of stillbirth after IVF/ICSI was 16.2 per thousand, compared to 3.7 per thousand in fertile couples who conceived without medical help.
The researchers said it was not yet clear whether the increased risk was due to the fertility treatment itself or because of unknown factors specific to couples who IVF or ICSI.
IVF is the fertilization of an egg by sperm in a laboratory dish. In ICSI, an egg is fertilized by injecting a single sperm into it.
Doctors previously thought the greater risk of bad outcomes like stillbirths in assisted reproduction might be something to do with the underlying infertility of couples who have it.
But Wisborg and colleagues found that fertile couples who conceived within a year of trying, and so-called "sub-fertile" couples who took longer to conceive, had a similar risk to each other.
"This may indicate that the increased risk of stillbirth is not explained by infertility and may be due to other, as yet unexplained factors, such as the technology involved in IVF and ICSI or some physiological difference in the couples that require (it)," Wisborg wrote.
