Women who have fertility treatment are four times more likely to have a stillborn baby than those who conceive naturally, a study published on Tuesday said.
It has been known for some time that there was an increased risk that a baby conceived through IVF (in-vitro fertilization, in which sperm and eggs are mixed in a test tube) or ICSI (in which the sperm is injected into the egg) would be stillborn. But previous studies have not been able to show the scale of baby deaths.
Researchers say women contemplating fertility treatment should not be unduly anxious.
Kirsten Wisborg, who led the study, said: “The risk of stillbirth is still very low after IVF/ICSI. We do not know whether increased risk is due to the fertility treatment or to factors pertaining to couples who undergo IVF/ICSI.”
The fourfold difference was between women who had either IVF or ICSI and women who conceived either naturally or through other methods, such as taking hormones to stimulate their egg production or artificial insemination.
The study, published in the journal Human Reproduction, involved more than 20,000 singleton pregnancies in Aarhus, Denmark. Wisborg and colleagues analyzed data that has been kept on pregnant women between 1989 and 2006, who form the Aarhus Birth Cohort. They had a wealth of data on the pregnancies and outcomes, including how long it took the women to become pregnant, smoking and drinking habits, age and education.
Out of 20,166 first-time singleton pregnancies, 82 percent were conceived spontaneously within 12 months and 10 percent after more than a year of trying. Of the rest, 4 percent were conceived after IVF or ICSI and 4 percent after other forms of fertility treatment. There were 86 stillbirths, giving an overall risk of 4.3 per thousand pregnancies. But the risk of stillbirths in women who had undergone IVF or ICSI was significantly higher, at 16.2 per thousand.
The stillbirth rate among women who had undergone other fertility treatment, such as hormone stimulation, was lowest, at 2.3 per thousand.
Of those who became pregnant spontaneously within 12 months of trying it was 3.7 per thousand and among those who took more than a year to get pregnant it was 5.4 per thousand.
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