Infertility treatment linked to birth defects
The medical literature contains evidence that assisted reproductive technology (ART) procedures such as in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI) are associated with an increased risk of birth defects. Because these studies evaluated a small number of patients, researchers at Perth Australia conducted large study. Their results were published May 5 in the New England Journal of Medicine.
IVF involves retrieving ova (eggs) from a woman, fertilizing them with semen (from husband or donor) and then inserting them into the uterus following fertilization. ICSI involves laboratory techniques to aid fertilization of the ova when natural fertilization is compromised. The researchers reviewed data from 308,974 records from two infertility clinics in South Australia. Both clinics provided data for all infertility treatments from January 1986 through December 2002. Among those records, they located 6,163 cases on which ART was employed. They reviewed records of births and pregnancies terminated because of birth defects in order to determine the risks of defects from pregnancy to a child's fifth birthday. The birth defect risk was compared between women who underwent ART and women who had not.
The researchers found differences between those that had undergone IVF and those that had not. The women undergoing ART were generally older than the women who conceived spontaneously; furthermore they were more likely to be nulliparous (no previous child) and live in a more affluent community. The rate of smoking during pregnancy was lower in the IVF group; however, the percentage of women with diabetes, hypertension, pregnancy-induced hypertension, urinary tract infection, and anemia was significantly higher.
The authors found a strong relationship between ART and an overall risk for birth defects, compared to women who conceived spontaneously (spontaneous conception: 513 defects; ART: 17,456 defects). The risk was found to be less after adjusting for smoking during pregnancy, maternal age, parity (number of pregnancies), fetal sex, race/ethnic group, nation of birth, pregnancy factors, smoking during pregnancy, socioeconomic status, and maternal/paternal occupations; however, it still remained significant.
The researchers did not find a significant difference in birth defects between single and twin pregnancies; however, twins were more likely to suffer from respiratory problems, and single pregnancies were more likely to have multiple defects, congenital abnormalities, cerebral palsy, as well as cardiovascular, musculoskeletal, and urogenital defects.
The authors concluded that although the large majority of births resulting from ART were free of birth defects, assisted reproduction was associated with an increased risk of birth defects, including cerebral palsy, when compared with spontaneous conception. In cases of ICSI, but not IVF, the increased risk of birth defects persisted after adjustment for maternal age and several other risk factors. The authors noted that although they could not out the possibility that other patient factors contribute to or explain the increased risk, their findings might help provide guidance in counseling patients who are considering ART.
Reference: The New England Journal of Medicine