Contrary to some previous studies, this latest research suggests infertility treatment does not affect offspring's risk of early developmental disabilities.
Edwina Yeung, PhD, of the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD) - part of the National Institutes of Health (NIH) - and colleagues publish their findings in JAMA Pediatrics.
According to Centers for Disease Control and Prevention (CDC), around 1.5% of all infants in the US are conceived using assisted reproductive technology (ART), such as in vitro fertilization (IVF).
Previous studies have suggested such treatment may lead to developmental problems among offspring; Yeung and colleagues point to a 2013 Swedish study that identified an 18% greater risk of intellectual disability among children conceived through a form of ART called intracytoplasmic sperm injection (ICSI). However, many other studies have found no such association.
Additionally, the researchers note that few studies have assessed how non-ART infertility treatments, such as ovulation induction (OI) - the stimulation of ovulation through medication - impacts the risk for developmental delays among offspring.
"In response to critical data gaps, we designed the Upstate KIDS Study to specifically assess the association between the mode of conception and children's development through age 3 years," say the authors.
Drawing data on infertility treatment types and offspring's development
The Upstate KIDS Study involved 1,422 mothers of 1,830 children who were conceived through infertility treatment and 3,402 mothers of 4,011 children who were not conceived through such treatment. All children were born in New York State between 2008-2010.
The team notes that parents of twins and other multiples were included in the study, and there were around three times as many singleton children in the non-treatment group than the treatment group.
Four months after the mothers gave birth, they were asked to complete a questionnaire detailing the type of infertility treatment they underwent. These included ART treatments, such as IVF, frozen embryo transfer, assisted hatching and zygote intrafallopian transfer, and the non-ART treatment OI, with or without intrauterine insemination (IUI).
When the children were aged 4-6, 8, 12, 18, 24 and 36 months, their mothers completed a questionnaire that was used to identify developmental disabilities. Specifically, the questionnaire was used to assess children's fine motor skills, gross motor skills, communication, problem-solving abilities and personal and social functioning.
Findings 'provide reassurance' to couples receiving infertility treatment
Overall, the researchers found there was no difference in the risk of developmental disabilities between children conceived via infertility treatment - regardless of ART or non-ART treatments - and those who were not.
Accounting only for children who were conceived via ART, the researchers found they were more likely than those in the non-treatment group to have developmental delays; they were most likely to have difficulties with problem-solving and personal and social functioning.
However, when the team accounted for the significantly higher number of twins in the ART group - after noticing twins were at higher risk of developmental problems than singletons - there was no difference in the risk of developmental disabilities between children conceived through ART and those in the non-treatment group.
Additionally, the researchers found no difference in the percentage of children who were referred for assessment by developmental specialists between treatment and non-treatment groups.
Among children who were diagnosed with a developmental disability aged 3-4 years, the researchers identified no significant differences between those conceived through infertility treatment and those who were not.
These findings, according to the researchers, indicate that infertility treatment does not affect the development of offspring up to the age of 3 years. Yeung adds:
"When we began our study, there was little research on the potential effects of conception via fertility treatments on US children. Our results provide reassurance to the thousands of couples who have relied on these treatments to establish their families."
However, the team notes that some forms of developmental disability cannot be diagnosed by the age of 3 years. As such, they will continue to assess the children regularly until they reach 8 years old.
Last year, Medical News Today reported on a study suggesting maternal stress in pregnancy may impact a child's motor development.