After mapping the relationship between the length of pregnancy and chemical DNA changes in newborn babies, researchers have found that length of pregnancy alters the DNA of the child.

The researchers from Sweden's Karolinska Institutet mapped the chemical DNA changes in more than 6,000 newborn babies. The study was published in the journal - Genome Medicine. For each week's longer pregnancy, DNA methylation changes in thousands of genes were detected in the umbilical cord blood. The study is published in Genome Medicine. Premature birth, that is before 37 consecutive weeks' of pregnancy, is common. Between 5 and 10% of all children in the world are born prematurely. Most children will develop and grow normally, but premature birth is also linked to respiratory and lung disease, eye problems and neurodevelopmental disorders.

This is especially true for children who are born very or extremely prematurely. During the fetal period, epigenetic processes, i.e., chemical modification of the DNA, are important for controlling development and growth. One such epigenetic factor is DNA methylation, which in turn affects the degree of gene activation and how much of a particular protein is formed.
"Our new findings indicate that these DNA changes may influence the development of fetal organs," said the lead researcher Simon Kebede Merid.

The majority of observed DNA methylations at birth tended not to persist into childhood, but in 17% the levels were completely stable from birth to adolescence. The levels that you are born with in certain genes thus track with age. "Now we need to investigate whether the DNA changes are linked to the health problems of those born prematurely," said Professor Erik Melen. Epigenetics is a hot research topic that links genes, the environment and health. This work was done within the international Pregnancy and Childhood Epigenetics (PACE) consortium.

The work represents contributions from 26 studies. Professor Melen's group also contributed to the first PACE paper which showed that mother's smoking during pregnancy changes DNA in newborns and lead two PACE studies showing the effects of air pollution. Links to diseases such as asthma, allergy, obesity and even ageing have also been shown. "We hope that our new findings will contribute valuable knowledge about fetal development, and in the long term new opportunities for better care of premature babies to avoid complications and adverse health effects," said Erik Melen.