Many genes in male and female placentas expressed differently

Thursday, May 1, 2025

NIH findings may lead to insights on pregnancy complications, adult health

The genes of male and female placentas have marked differences in how they are expressed, according to a study by researchers at the National Institutes of Health (NIH) and other institutions. These differences involve the presence or absence of tags on DNA known as methyl groups, which switch genes on or off without changing their structure. Understanding these DNA methylation patterns may inform future research on the higher risk for pregnancy complications involving male fetuses, such as stillbirth and prematurity, as well as later life health conditions that occur in adults who were born after a complicated pregnancy.

Researchers analyzed male and female placental samples from a larger study for differences in their methylation patterns, and found differences in gene activity between male and female placentas that may play a role in birthweight and adult diseases.

The study identified 2,497 previously unreported DNA sites that had different methylation patterns for males and females. Of these and more than 2,500 sites that had also been identified by previous studies, 66.9 percent of large increases in methylation occurred in DNA from male placentas and 33.1 percent from female placentas. Increases in methylation in male placentas was linked with greater neonatal size whereas those in females was linked with greater placental size.