The mother and baby genetics contributes to most cases in which babies they are born very big or very small, according to new research published in the journal ‘PLOS Genetics’.
A large-scale study, led by the University of Exeter and the University of Cardiff, in the UK, has found the strongest evidence to date that genetics play an important role in most cases when full-term babies are in the top or bottom 10% of the weight spectrum.
However, in the three percent of babies with the lowest birth weight, genetics seemed to play a less important role. This indicated that other factors may be contributing to the small size of the babies. The research examined 190 common genetic variations known to affect birth weight, however rare genetic changes in the baby may reduce growth by a minimum of three percent. Other important factors could include the health of the mother or fetus or the placenta, which transfers nutrients and oxygen to the baby.
The study was a collaboration in which the ‘Children of the 90s’ study from the University of Bristol, Imperial College London and the University of Oulu in Finland also participated. The research was supported by the Wellcome Trust and the European Commission’s H2020 program.
Babies’ birth weights are importantas those born at the extremes have a higher risk of complications. Smaller babies are more likely to be admitted to neonatal units and have a higher risk of death, while older babies have a higher risk of complications during delivery.
To examine the extent to which birth weight was related to the genetics of mothers and babies, the team created a genetic score for higher birth weight. The study evaluated whether the score was higher or lower in babies who were born very large or very small in a sample of nearly 12,000 babies and more than 5,000 mothers of European descent.
The doctor Robin Beaumont, from the University of Exeter School of Medicine and lead author of the study stresses that «this research sheds new light on why some babies are born too big or too small. This knowledge will help both parents and physicians understand where to focus medical care. Genetics played a minor role in the three percent of babies with the lowest weight, suggesting that other factors, such as the health of the placenta, may have influenced their weight.
Co-lead author and physician, Professor Sailesh Kotecha, from Cardiff University, adds that «It is important to identify the reasons why babies are born with low birth weight, as they are at risk for further health problems in adulthood, including diabetes and high blood pressure ‘.
“Our work shows that genetics is a key part of the reason why some babies are born small – he emphasizes -, and raises the possibility that genetics can be used in conjunction with maternal and placental factors to identify those most likely not to reach their growth potential ‘.
The teacher Rachel Freathy, from the University of Exeter, which supervised the study, concludes that the study ‘provides the most information to date on how genetic variations Common among people influence extremes of birth weight. Now we need to better understand whether genetics or environmental factors are more important in later life health risks, “he advances.
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