The study also indicates that methylation tags can influence gene expression, which may have long-term implications for health beyond pregnancy.

FNDC5 is essential for the production of irisin, a protective factor for the placenta, and lower levels of irisin are linked to preeclampsia, a common pregnancy complication.

Overall, the findings underscore the importance of understanding DNA methylation as a factor influencing both pregnancy complications and potential health issues later in life.

These significant findings were published in the journal Nature Communications on May 2, 2025.

A recent study from the National Institutes of Health has uncovered significant differences in gene expression between male and female placentas, primarily driven by DNA methylation patterns.

Notably, 66.9% of significant increases in methylation were observed in male placentas, which correlated with greater neonatal size, whereas increases in female placentas were associated with larger placental size.

These DNA methylation patterns involve chemical tags that regulate gene activity without changing the DNA structure, playing a crucial role in pregnancy outcomes.

In female placentas, genetic variations in the ATP5MG and FAM83A genes have been linked to heightened risks of asthma, hay fever, eczema, and breast cancer later in life.

Specifically, increased methylation near the CCDC6 gene in male placentas was associated with preterm birth, while higher methylation near the FNDC5 gene correlated with reduced gene expression.

The research highlights that male fetuses tend to grow faster than females but are at a higher risk for complications such as preeclampsia, growth failure, and preterm birth, along with increased mortality rates in their first year.