Fatter Women Have Fatter Babies
Author: Imperial College London
Published: 20 Aug 2011 - Updated: 16 Jul 2026
Publication Details: Peer-Reviewed | Findings
Table of Contents:
Synopsis - Definition - Overview - FAQs - Insights, Updates - Related Content
Synopsis
This research reports that babies born to mothers with a higher pre-pregnancy body mass index (BMI) tend to carry more body fat and more fat within their liver cells, based on magnetic resonance scans of 105 sleeping newborns at Chelsea and Westminster Hospital. Led by Professor Neena Modi at Imperial College London, the study found that liver cell fat and total body fat, particularly around the abdomen, rose across the entire range of maternal BMI rather than only among overweight or obese mothers. The findings matter to expectant parents, healthcare providers, and families managing weight-related health, because they suggest the biological groundwork for lifelong metabolic problems such as type-2 diabetes may begin in the womb, meaning prevention of childhood obesity can start before birth. Published in the peer-reviewed journal Pediatric Research and funded by the Medical Research Council and Chelsea and Westminster Hospital NHS Foundation Trust, the work is authoritative because it uses advanced proton imaging and spectroscopy to measure fat directly, offering measurable evidence that can inform prenatal care and preconception planning for all women, including those with disabilities or conditions that affect weight.*At a Glance
- 1 - Of the 105 mothers studied, five were underweight, 69 were normal weight, 23 were overweight, and eight were obese.
- 2 - Researchers noted that about half of women of childbearing age in the UK are overweight or obese, making optimal maternal BMI an open question.
- 3 - In adults, high levels of both total body fat and fat inside liver cells correlate strongly with impaired control of blood sugar, which the imaging measured directly in the newborns.
Topic Definition
- Maternal BMI and Infant Adiposity
Maternal BMI and infant adiposity refers to the relationship between a mother's body mass index, a measure of weight relative to height, and the amount of fat carried by her baby at birth. Body mass index is calculated by dividing a person's weight in kilograms by the square of their height in meters, with the World Health Organization classing 18.5 to 25 as normal weight, 25 to 30 as overweight, and over 30 as obese. Infant adiposity describes the total quantity and distribution of fat in a newborn's body, including fat stored inside liver cells. Studying the two together helps researchers understand how conditions in the womb may shape a child's early body composition and potentially influence their long-term metabolic health, including future diabetes risk.
Overview
Maternal BMI Effects on Infant Body Fat and Liver Health
Babies of mothers with a higher pre-pregnancy body mass index (BMI) are fatter and have more fat in their liver, a study published in September's issue of the journal Pediatric Research has found. 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 child 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.
Funding Disclosure
The research was funded by the Medical Research Council and Chelsea and Westminster Hospital NHS Foundation Trust. 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.
Frequently Asked Questions
NOTE: Researched FAQs by Disabled World (DW)
How is body mass index calculated?
Body mass index is calculated by dividing a person's weight in kilograms by the square of their height in meters, and it is used as a general screening measure of body weight.
Why do researchers scan newborns while they sleep?
Scanning babies while they are asleep allows researchers to use magnetic resonance imaging safely and without sedation, keeping the infant still enough to measure fat accurately.
Is magnetic resonance imaging safe for babies?
Magnetic resonance imaging does not use ionizing radiation, which makes it a preferred method for studying infants when careful clinical protocols are followed.
Can a mother lower her BMI before pregnancy?
Many women can work toward a healthier weight before conceiving through diet, activity, and medical guidance, and a doctor can help create a plan suited to individual health needs.
What is intra-hepatocellular lipid?
Intra-hepatocellular lipid is the fat stored inside liver cells, and elevated levels are associated in adults with impaired control of blood sugar.
Does a normal BMI mean there is no risk to the baby?
The study found that fat levels in babies rose across the entire BMI range, so even mothers within the normal range showed the association, though risks differ by individual.
What is type-2 diabetes?
Type-2 diabetes is a long-term condition in which the body does not use insulin effectively, leading to high blood sugar, and it is linked to excess body fat and lifestyle factors.
Insights, Analysis, and Developments
Editorial Note: The lasting significance of this work is its argument that efforts to prevent childhood obesity may need to begin before conception rather than in early childhood. Because the link between a mother's BMI and her baby's fat levels held across the full BMI spectrum, the message reaches beyond women in the overweight or obese categories and speaks to anyone planning a pregnancy, alongside the clinicians who support them. It also points toward a broader public health conversation about accessible, non-judgmental care that addresses nutrition and weight before pregnancy, while acknowledging that BMI is an imperfect measure that does not capture individual differences in muscle mass, body composition, or overall health - a caveat worth keeping in view as researchers work to define what an optimal maternal BMI might actually be.*Attribution/Source(s): This peer reviewed publication was selected for publishing by the editors of Disabled World (DW) due to its relevance to the disability community. Originally authored by Imperial College London and published on 20 Aug 2011, this content may have been edited for style, clarity, or brevity.
* Editorial additions by Ian C. Langtree.