Fetal risks related to assisted reproductive technology and insemination

Compared to babies naturally conceived, those conceived with assisted reproductive technologies (ART) have a higher risk of low birth weight and birth defects.^{1, 2} (Most ART research currently focuses on in vitro fertilization and intracytoplasmic sperm injection [ICSI].) Babies conceived using intrauterine insemination (IUI) also have an increased risk of low birth weight.³

Possible birth defect risks. ICSI is a relatively new ART procedure that has raised concerns about increased birth defect rates in the past few years. While some studies have found no differences between ICSI and babies conceived naturally, a large, multicenter study has recently identified higher rates of certain birth defects in ICSI offspring. In this study, newborns as well as fetuses that were not liveborn were examined. Overall, "major malformations" that impact quality of life and need medical attention affected 8.6% of ICSI babies, versus 6.9% of babies conceived naturally. The most common problems were heart and internal urinary/genital defects. Heart defects affected 2.1% of ICSI babies and 1.1% of non-ICSI babies, while internal urinary/genital defects affected 2.5% of ICSI and 1.6% of non-ICSI babies.²

Possible causes. Experts have yet to fully understand the underlying reasons for ART and IUI risks. However, the following factors are known or possible causes:

• Premature birth poses the biggest and most proven risk to ART or IUI pregnancies involving twins, triplets, or more. Multiple fetuses are usually born prematurely and at low birth weight, with an increased risk of complications (including cerebral palsy) related to lung immaturity, brain immaturity, or other organ systems that aren't fully developed.
• Parent-related factors, yet to be fully understood, are thought to be linked to fetal risks. ICSI researchers believe that some birth defect risks may be related to parental genetic or other physical factors, rather than the ART procedure itself.² As another example, while IUI using donor sperm doesn't seem to increase the risk of low birth weight, IUI using a subfertile couple's sperm produces more than 5 times as many low-birth-weight babies as normal.³
• Hormone medications and technologies used for ART may increase fetal risks. Studies have shown that single-born, full-term ART babies are more commonly low birth weight than those naturally conceived.¹ (Researchers have yet to separate this possible cause from parental factors as a cause.)

Citations

1. Schieve LA, et al. (2002). Low and very low-birth-weight in infants conceived with use of assisted reproductive technology. New England Journal of Medicine, 346(10): 731–737.

2. Ludwig M, Katalinic A (2002). Malformation rate in fetuses and children conceived after ICSI: Results of a prospective cohort study. Reproductive Biomedicine Online, 5(2): 171–178.

3. Gaudoin M, et al. (2003). Ovulation induction/intrauterine insemination in infertile couple is associated with low-birth-weight infants. American Journal of Obstetrics and Gynecology, 188(3): 611–616.