Gestational age, is normally estimated by obstetricians using ultrasound during the first trimester, by asking a pregnant woman about her last menstrual period, or by examining the baby at birth. Ultrasound is considered to be the most precise estimate of gestational age. This work extends upon earlier studies of DNA methylation patterns that change over development and predict age and age-related health conditions in children and adults.

The new method could help doctors assess developmental maturity in preterm newborns and make decisions about their care, or estimate the time since conception for a woman who does not receive prenatal care during pregnancy.

 As a research tool, the method could help scientists study connections between the prenatal environment and health in early childhood and adulthood.

The study used blood samples from more than 1,200 newborns in 15 cohorts from around the world. The results are published in Genome Biology.

The Emory team gathered DNA methylation data from previous studies examining live births and health outcomes, and used an unbiased statistical learning approach to select 148 DNA methylation sites out of many thousands in the genome. By examining methylation at those sites, gestational age could be accurately estimated between 24 and 44 weeks, the authors report. The median difference between age determined by DNA methylation and age determined by an obstetrician estimate was approximately 1 week.

The researchers also found that the difference between a newborn's age predicted by DNA methylation and by an obstetrician may be another indicator of developmental maturity, and is correlated with birthweight, commonly used as an indicator of perinatal health.

In a group of newborns from Tennessee, the researchers observed that developmental maturity based on DNA methylation tended to be lower for the children of women in the Medicaid program compared to those with private health insurance. It is not yet clear if this finding can be extended to other groups, the authors say.

"This association supports the hypothesis that prenatal adversity associates with changes in neonatal methylation consistent with a delayed developmental age, which may have consequences later in life," the authors write.

http://news.emory.edu/stories/2016/10/gestational_age_genomebio/index.html