The researchers from Imperial College London say that the effect of a mother's BMI on her child's development in the womb might put them on a trajectory towards lifelong metabolic health problems.
The research team used magnetic resonance scanning to assess 105 babies born at Chelsea and Westminster Hospital. The babies were scanned while they were asleep to measure the amount of fat in their liver cells, the total amount of fat in their bodies and its distribution. They found that liver cell fat in the babies and total fat, particularly around the abdomen, increased across the entire range of BMI in their mothers.
Children of overweight and obese mothers are already known to have a higher risk of being overweight and obese themselves, and of experiencing associated metabolic health problems such as type-2 diabetes. The authors of this new study suggest that the changes they found in babies' bodies might be signs of the first biological changes which, combined with an unhealthy lifestyle, might put babies of overweight mothers on a path to ill health in later life.
Professor Neena Modi, from the Department of Medicine at Imperial College London and a Consultant Neonatologist at Chelsea and Westminster Hospital, who led the study, said: "This study demonstrates that a woman's BMI, even in the normal range, affects the amount of fat in her baby at birth. Fatter women have fatter babies and there is more fat in the babies livers. If these effects persist through childhood and beyond, they could put the child at risk of lifelong metabolic health problems.
"There is growing evidence that a baby's development before birth has a major impact on their health in later life. This means that the prevention of obesity needs to begin in the womb.
"Today about half of all women of childbearing age in the UK are overweight or obese. Importantly, the link between maternal BMI and amount of fat in the baby spreads across the entire range of BMI, meaning it's not just an issue for overweight and obese mums. We need to identify what the optimal BMI for the mother is so we can help women ensure that their bodies are in the best possible condition before they get pregnant."
Body mass index is calculated by dividing one's weight in kilograms by the square of their height in meters. The World Health Organization classes a BMI between 18.5 and 25 as normal weight, between 25 and 30 as overweight and over 30 as obese. Of the 105 mothers in the study, five were underweight, 69 were normal weight, 23 were overweight and eight were obese.
The researchers used proton magnetic resonance imaging and spectroscopy to measure total adipose tissue and its distribution and intra-hepatocellular lipid (the amount of fat inside liver cells). In adults, high levels of both correlate strongly with impaired control of blood sugar.
The research was funded by the Medical Research Council and Chelsea and Westminster Hospital NHS Foundation Trust.
1. Journal reference: N. Modi et al. 'The influence of maternal body mass index on infant adiposity and hepatic lipid content.' Pediatric Research, Volume 70 - Issue 3, September 2011.
2. About Imperial College London - Consistently rated amongst the world's best universities, Imperial College London is a science-based institution with a reputation for excellence in teaching and research that attracts 14,000 students and 6,000 staff of the highest international quality. Innovative research at the College explores the interface between science, medicine, engineering and business, delivering practical solutions that improve quality of life and the environment - underpinned by a dynamic enterprise culture.
Since its foundation in 1907, Imperial's contributions to society have included the discovery of penicillin, the development of holography and the foundations of fiber optics. This commitment to the application of research for the benefit of all continues today, with current focuses including interdisciplinary collaborations to improve global health, tackle climate change, develop sustainable sources of energy and address security challenges.
In 2007, Imperial College London and Imperial College Healthcare NHS Trust formed the UK's first Academic Health Science Center. This unique partnership aims to improve the quality of life of patients and populations by taking new discoveries and translating them into new therapies as quickly as possible. Website: www.imperial.ac.uk
3. About the Medical Research Council - For almost 100 years the Medical Research Council has improved the health of people in the UK and around the world by supporting the highest quality science. The MRC invests in world-class scientists. It has produced 29 Nobel Prize winners and sustains a flourishing environment for internationally recognized research. The MRC focuses on making an impact and provides the financial muscle and scientific expertise behind medical breakthroughs, including one of the first antibiotics penicillin, the structure of DNA and the lethal link between smoking and cancer. Today MRC funded scientists tackle research into the major health challenges of the 21st century. www.mrc.ac.uk
4. About Chelsea and Westminster Hospital NHS Foundation Trust - Chelsea and Westminster Hospital NHS Foundation Trust is a major London teaching hospital which is consistently rated among the best hospitals in the UK by independent sources including the Dr Foster Hospital and the CHKS Top Hospitals program. Delivering excellence in teaching and research is one of the Trust's corporate objectives - in 2010/11, the Trust hosted 217 research projects and recruited more than 4,000 patients into clinical studies.