Nav: Home

How both mother and baby genes affect birth weight

May 01, 2019

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.

The study found that some parts of the genetic code can be linked to birth weight both directly from the child and indirectly from the mother. A number of these were seen to work together, with the mother and baby effects pushing birth weight in the same direction, while others had opposing effects, like a mother-baby tug of war. For example, some of the genetic effects that raise the mother's glucose levels work to make the baby bigger because the baby produces more insulin in response which makes it grow. But when those same variations in the genetic code are inherited by the child, they restrict the amount of insulin the baby can produce, so limiting its growth and counter-acting some of the mother's growth-promoting effects.

Dr Rachel Freathy, a Sir Henry Dale Fellow at the University of Exeter Medical School, who was joint lead author on the study, said: "This is the first time we've really been able to unpick the effects of both mother and baby's genes on baby weight, which is an important health indicator. It's particularly useful to know about the maternal genetic influences on the environment in the womb because these give us clues as to which factors are causal. Better understanding of the causes may mean we can help ensure babies are born at healthy weights."

Dr Nicole Warrington, at the University of Queensland and joint first author on the study said: "The methods we have developed to disentangle the mother and baby's genetic effects have a real potential not only to tell us about the effects of the womb environment on a baby's growth but also about the possible effects of that environment on later-life outcomes. For example, smaller babies are more likely to have higher blood pressure in adulthood. Our work shows that this is due to genetic effects; we found no evidence that exposure to the womb environment can raise your blood pressure in later-life."

Dr Robin Beaumont, at the University of Exeter Medical School, joint first author on the study, said: "This study highlights the value of large-scale international research collaborations. It's really satisfying to bring together a wide range of experts to analyse largescale datasets to advance understanding in key areas of human health."

The research involved more than 200 international researchers from 20 countries who are members of the Early Growth Genetics (EGG) Consortium. The work was supported by more than 120 research funders: the major sources of funding for UK researchers were the Wellcome Trust, the Royal Society, the Medical Research Council, the National Institute for Health Research and the European Union."
-end-
The paper, "Maternal and fetal genetic effects on birth weight and their relevance to cardio-metabolic risk factors", is published in Nature Genetics.

University of Exeter

Related Blood Pressure Articles:

Arm cuff blood pressure measurements may fall short for predicting heart disease risk in some people with resistant high blood pressure
A measurement of central blood pressure in people with difficult-to-treat high blood pressure could help reduce risk of heart disease better than traditional arm cuff readings for some patients, according to preliminary research presented at the American Heart Association's Hypertension 2019 Scientific Sessions.
Heating pads may lower blood pressure in people with high blood pressure when lying down
In people with supine hypertension due to autonomic failure, a condition that increases blood pressure when lying down, overnight heat therapy significantly decreased systolic blood pressure compared to a placebo.
The Lancet Neurology: High blood pressure and rising blood pressure between ages 36-53 are associated with smaller brain volume and white matter lesions in later years
A study of the world's oldest, continuously-studied birth cohort tracked blood pressure from early adulthood through to late life and explored its influence on brain pathologies detected using brain scanning in their early 70s.
Blood pressure control is beneficial, is it not?
Until recently, physicians had generally assumed that older adults benefit from keeping their blood pressure below 140/90 mmHg.
The 'blue' in blueberries can help lower blood pressure
A new study published in the Journal of Gerontology Series A has found that eating 200g of blueberries every day for a month can lead to an improvement in blood vessel function and a decrease in systolic blood pressure in healthy people.
How to classify high blood pressure in pregnancy?
The American Heart Association (AHA) and the American College of Cardiology (ACC) changed their guidance to lower the threshold criteria for hypertension in adults.
Discovery could advance blood pressure treatments
A team of Vanderbilt University Medical Center researchers, working with the US Department of Veteran's Affairs (VA), has discovered genetic associations with blood pressure that could guide future treatments for patients with hypertension.
Blue light can reduce blood pressure
Exposure to blue light decreases blood pressure, reducing the risk of developing cardiovascular disease, a new study from the University of Surrey and Heinrich Heine University Dusseldorf in collaboration with Philips reports.
Poor oral health linked to higher blood pressure, worse blood pressure control
Poor oral health may interfere with blood pressure control in people diagnosed with hypertension.
Largest ever genetic study of blood pressure
The largest ever genetic analysis of over one million people has identified 535 new genes associated with high blood pressure.
More Blood Pressure News and Blood Pressure Current Events

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Rethinking Anger
Anger is universal and complex: it can be quiet, festering, justified, vengeful, and destructive. This hour, TED speakers explore the many sides of anger, why we need it, and who's allowed to feel it. Guests include psychologists Ryan Martin and Russell Kolts, writer Soraya Chemaly, former talk radio host Lisa Fritsch, and business professor Dan Moshavi.
Now Playing: Science for the People

#538 Nobels and Astrophysics
This week we start with this year's physics Nobel Prize awarded to Jim Peebles, Michel Mayor, and Didier Queloz and finish with a discussion of the Nobel Prizes as a way to award and highlight important science. Are they still relevant? When science breakthroughs are built on the backs of hundreds -- and sometimes thousands -- of people's hard work, how do you pick just three to highlight? Join host Rachelle Saunders and astrophysicist, author, and science communicator Ethan Siegel for their chat about astrophysics and Nobel Prizes.