Assisted Reproductive Technology and Developmental Outcomes

Assisted reproductive technologies (ARTs), including in vitro fertilization with fresh or frozen embryos as well as intracytoplasmic sperm injection, have come into increasing use in Western nations since the late 1970s. Pregnancies resulting from ART are more likely to result in stillbirth, multiple gestation, preterm delivery, and low birth weight, with higher rates of adverse outcomes after procedures that involve the placing of either a single embryo or multiple embryos.¹ Infant mortality rates are higher as well, whereas evidence for an increased risk of specific birth defects is equivocal.^2,–4 Research on child health and developmental outcomes is more limited, and for this reason, the study by Hansen et al⁵ is a welcome addition to our literature.

Hansen et al⁵ use population-based data from Western Australia garnered through probabilistic record linkage based on personal identifiers, dates, and personal characteristics in health and social services records of several databases enumerating pregnancy outcomes, ART procedures and outcomes, birth defects, mortality, and intellectual disabilities. These databases have previously been employed to address a number of hypotheses regarding longer-term outcomes in children with adverse pregnancy outcomes, and the linkage methodologies have been well documented in the research literature.

The authors of this study examined outcomes for >200 000 children born in Western Australia during 1994–2002 who survived and had at least 8 years of follow-up. Although the sample of children conceived through ART was smaller (with 2876 cases), there was sufficient power to examine outcomes for several ART subgroups. Although children born after ART were slightly more likely to have mild or moderate intellectual deficiency (adjusted odds ratio 1.51; confidence interval 1.11–2.06), these children were more than twice as likely to have severe intellectual disability (adjusted odds ratio 2.55; confidence interval 1.19–5.44). Differences in the prevalence of intellectual disability were also found when comparing ART subgroups, with the risk of intellectual disability being approximately twice as high among those conceived with intracytoplasmic sperm injection compared with that of those conceived with standard in vitro fertilization treatment among all cases (and not just singletons) as well as for frozen embryos (but not for fresh embryos). The authors of the study also present data on known causes of intellectual disability by type of conception, but these results are incomplete, with cause data available for only 28.3% of ART cases and 17.9% of non-ART cases. Data on coexisting disabilities are also provided, but more details are necessary to fully interpret these patterns. Also of interest would be patterns of placement in special education programs and early intervention services.

Families in the United States will be interested to see the results of similar studies in North American populations. However, challenges abound in collating the necessary longitudinal data across samples of sufficient size to replicate the Western Australian study.⁵ Although there is a national database consisting of individual records from most ART clinics in the United States (and this has been linked with vital statistics for several states⁶), individual-level data on developmental disabilities or special education services are more difficult to obtain in most US states. These data are also subject to data quality issues, including completeness of ascertainment and diagnostic heterogeneity by type of practitioner as well as differences in access to care and availability of diagnostic and follow-up services across rural and urban areas and within metropolitan regions. One can only hope that forward-looking education and human services administrators will recognize the importance of working with perinatal and pediatric epidemiologists to develop similar population databases to answer important questions concerning the risks and outcomes of fertility treatments that have become relatively common in the United States in recent years.

ART

assisted reproductive technology