Obesity in pregnancy can alter the brain wiring of babies and leave them prone to long-term disorders such as diabetes and uncontrolled weight gain, a study suggests.
Scientists made the discovery after investigating why children whose mothers are obese are at greater risk of metabolic problems as they age.
The research showed that newborn mice nourished by the milk of mothers on a high-fat diet developed abnormal nerve circuits in a region of the brain key to regulating metabolism.
Taking species differences into account, the findings imply that a human mother's nutrition in the last three months of pregnancy is critical to her child's future health.
"Our study suggests that expecting mothers can have major impact on the long-term metabolic health of their children by properly controlling nutrition during this critical developmental period of the offspring," US researcher Professor Tamas Horvath, from Yale School of Medicine, said.
"Mothers can control or even reverse their offspring's predisposition to obesity and resulting diseases by altering their food intake."
Studies have confirmed that children of mothers who are obese or have diabetes are vulnerable to metabolic disorders, but it has not been clear why.
Previous research has also failed to pinpoint the most critical stage before or after birth when maternal nutrition has the greatest impact on a child's metabolic health.
To address these questions Prof Horvath's team and colleagues in Germany used a laboratory mouse bred to help them probe metabolic programming.
The researchers found that mouse mothers fed a high-fat diet during lactation had offspring with altered nerve connections in the hypothalamus region of the brain.
Abnormal signalling via the hormone insulin was also seen in the infant mice.
In humans, similar effects would be expected to occur earlier, in the last three months of pregnancy.
This is because neural circuits in the hypothalamus continue to develop after birth in mice but in humans they are fully formed in the womb.
The results of the research are published in the latest edition of the journal Cell.
Co-author Dr Jens Bruning, from the Max Planck Institute for Neurological Research in Germany, said: "Given that gestational diabetes frequently manifests during the third trimester, our results point toward the necessity of more intensified screening of mothers for altered glucose metabolism, as well as tightly controlled anti-diabetic therapy if any alterations are detected during this critical period."