Pregnant women who eat for two are storing up major health problems for themselves and their babies, researchers claim.
They have discovered how sugary foods eaten during pregnancy may permanently disrupt crucial processes in the mother and child.
These changes put the women and their babies at far higher risk of illnesses such as heart disease and diabetes in future.
Evidence of the complications was uncovered by Cambridge University researchers in a study of mice. But they believe the same problems are affecting pregnant women in the western world, particularly in the UK and the USA.
Women who are obese during pregnancy and their babies are known to be at far higher risk of high blood pressure, heart disease and type 2 diabetes later in life.
The researchers think the harm caused by sugary and fatty foods consumed during pregnancy may partly explain why. Women are being increasingly warned not to gain too much weight as it raises the risk of miscarriages, high blood pressure or complex births.
Chief Medical Officer Dame Sally Davies told them to abandon the eating-for-two myth in 2015 as they may be ‘shortening’ their lifespans. Health watchdog NICE says women only need to consume more food in the final three months of pregnancy.
Even then they should have a maximum daily surplus of 200 calories – equivalent to a full-fat latte or two breakfast biscuits.
Dr Amanda Sferruzzi-Perri, the lead author of the study, from St John’s College, Cambridge, claimed excessive sugar and fat were changing vital processes in the mother and baby.
She said: "In places like the UK, the US and Australia, many women of child-bearing age are also eating higher amounts of fat and sugar than the national dietary recommendations. We know that obesity during pregnancy is a risk factor for health complications for mother and baby both during and after pregnancy.
"We still don’t know what the exact consequences for the foetus are, but the findings match existing research which already suggests that the individual will suffer from these metabolic problems during adulthood. Dr Sferruzzi-Perri – whose study is published in the Journal of Physiology – also explained there was no need for pregnant women to eat extra calories as they adjusted their metabolism to ensure the foetus got an adequate supply of nutrients."
She said the changes altered the ‘metabolic memory’ of the mother and possibly the unborn baby.
This means they permanently changed the chemical processes by which food is broken down.
Meanwhile, official statistics suggest that almost half of pregnant British women are obese or overweight. Data from NHS Digital in 2016 found that 19 percent of women attending their first appointment with a midwife or GP were obese, and another 26 percent overweight.