How genes from mother and baby affect birth weight

The largest study of its kind has led to new insights into the complex relationships surrounding how mothers’ and babies’ genes influence birth weight. The research, published in Nature Genetics, identifies 190 links between our genetic code and birth weight, two-thirds of which are identified for the first time. It is the result of a […]

The largest study of its kind has led to new insights into the complex relationships surrounding how mothers’ and babies’ genes influence birth weight.

The research, published in Nature Genetics, identifies 190 links between our genetic code and birth weight, two-thirds of which are identified for the first time. It is the result of a largescale international collaboration, led by the universities of Exeter, Queensland, Oxford and Cambridge.

Scientists have long known that babies who are particularly small at birth have a higher risk of birth complications, and also tend to be more prone than average weight babies to high blood pressure in adulthood. To understand the relationships between birth weight and such risks to health, it is necessary to understand the contributions of both genetics and the environment. But until now, these have been unclear. This study casts new light in this area by allowing scientists to clearly separate the effects of a mother’s genetics on birth weight from the baby’s own genetics for the first time.

The research looked at genetic information from 230,069 mothers, with the birth weight of one child each, in addition to genetic information and birth weights of 321,223 people across the UK Biobank and the Early Growth Genetics consortium cohorts. They used novel statistical methods to tease apart the effects of the mothers’ and babies’ genes on the weight of newborn babies. Understanding the factors that influence birth weight is important because babies who are born very large or small have lower chance of survival and higher later-life risk of metabolic diseases.

A child inherits half their genes from their mother and half from their father, and the child’s own resulting genetic make-up plays a role in birth weight. The paper reveals the complex balance of how both the mother’s genes and the baby’s genes can influence the baby’s growth.

The researchers concluded that the direct effects of a baby’s genes made a substantial contribution to birth weight. However, around one-quarter of the genetic effects identified were from the mother’s genes that were not passed on to the child. Instead, these affected the baby’s growth by influencing factors in the baby’s environment during pregnancy, such as the amount of glucose available.

Courtesy: Nature Genetics