The risk of birth defects may increase with the use of assisted reproductive technologies such as in vitro fertilization, according to a Canadian study.
In a study of more than 61,000 deliveries in Ontario, Dr. Darine El Chaar of the University of Ottawa found that infants conceived using assisted reproduction were significantly more likely to be born with birth defects than infants conceived naturally.
Just under 1,400 of these children were conceived using assisted reproduction, including in vitro fertilization, intra-uterine insemination and ovulation induction.
The overall incidence of birth defects in the assisted pregnancies was 2.62 per cent, compared with 1.87 per cent in the naturally conceived pregnancies. After the researchers accounted for risk factors such as maternal age, smoking and delivery complications, infants conceived using assisted reproduction were 58 per cent more likely to be born with a birth defect than infants conceived naturally.
The risk for gastrointestinal malformations increased the most, followed by cardiovascular and musculoskeletal defects. There was no difference in facial defects or neural tube defects such as spina bifida. There was a trend toward the birth defect risk being higher with more complex approaches such as in vitro fertilization, but this could have been due to chance.
While the reasons for the differences in birth defect rates are not clear, El Chaar says there are several possible contributing factors. These include the underlying fertility of the couple, advanced age of infertile couples, medications involved in assisted reproduction, and the freezing and thawing of embryos.