Newborns conceived through in vitro fertilization (IVF) are more likely to have certain chemical modifications to their DNA, according to a study by researchers at the National Institutes of Health. The changes include DNA methylation—the attachment of compounds known as methyl groups to DNA—which can alter gene activity. The study found only small differences in DNA methylation at birth, and these were not observed in early childhood. Given that previous studies have found no differences in the growth and development of children, the current study should reassure anyone who has conceived through fertility treatments and those considering these methods. The researchers also called for more research into how variations in fertility treatments may contribute to methylation differences, such as variations in the medium used to culture embryos. The study was conducted by Edwina Yeung, Ph.D., and colleagues in NIH’s Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD).