OAKLAND, Calif. – In a new study, neither infertility history nor treatment for infertility was associated with risk of autism spectrum disorder (ASD) among singleton births. For multiple births, the results suggest that there may be some increase in risk of ASD associated with infertility history or treatment, but study researchers emphasize that more research is needed.
The study, which appears in the current issue of the Journal of Autism and Development Disorders, was led by researchers from The California Department of Public Health and Kaiser Permanente Division of Research working in collaboration with scientists from UCSF and Samuel Merritt University. The study is among the first to address the important question of whether a history of infertility or treatment for infertility is associated with an increased risk of ASD in children. “One reason this question has raised so much scientific and public concern”, said the researchers, “is that infertility is more common in older women, and for reasons not yet fully understood, older women are also at somewhat higher risk of having a child with ASD.”
“We found no evidence that infertility history or treatments increase the risk of ASD in singleton children” said Judith K Grether, PhD, the study’s lead author, formerly with the California Department of Public Health. “For multiple births, our results are less clear and more research is needed.”
”Because the number of multiple births in the study was too small for statistical adjustment for all demographic characteristics and because we lacked detailed data on most infertility treatments, further research is needed,” explained Lisa Croen, PhD, Director of the Kaiser Permanente Autism Research Program and a co-author on the study.
Researchers compared maternal medical record data on children with ASD (cases) and control children to evaluate infertility history and treatments for members of Kaiser Permanente in Northern California. The study population included 77, 403 children who were born in a Kaiser Pernanente Northern California facility from 1995-1998 and remained health plans members for at least two years following birth. From this population, children were identified as ASD cases if they had at least one diagnosis of ASD recorded in Kaiser Permanente Northern California data bases. For each child with ASD, researchers randomly selected five controls from the same study population. Infertility information was gathered from the mother’s medical records at Kaiser and from many specialty infertility clinics serving the same geographic region.
“As in any study of this type, there may be underlying factors we could not measure that explain our results,” said the researchers. “Most important, our findings on multiple births should be considered as very tentative given the small number of multiple birth children in this study and the lack of detailed data on infertility treatments. Also, as new treatments for infertility become available, new studies will be needed.”
Additional authors on the study include: Yinge Qian, with the Kaiser Permanente Division of Research; Mary S Croughan, PhD, with the UCSF Office of the President, Department of Obstetrics, Gynecology and Reproductive Sciences and the Department of Epidemiology and Biostatistics; Yvonne W. Wu, MD, MPH, with the UCSF Department of Neurology and Pediatrics; Michael Schembri, B.S. with the UCSF Department of Obstetrics, Gynecology and Reproductive Sciences; and Loretta Camarano, PhD, with the Samuel Merritt University School of Nursing. The study was funded by the Center for Disease Control and Prevention and, in part, by the National Cancer Institute, the National Institute of Child Health and Human Development, and the Kaiser Foundation Research Institute.