Women who develop diabetes while they are pregnant, or become pregnant while being overweight, put the long-term health of their children at risk, experts have warned.
Babies are being born addicted to sugar because their mothers eat too much during pregnancy.
The infants are being forced on to sugary drips just hours after birth to counter withdrawal symptoms.
Patrick O'Brien, Royal College of Obstetricians and Gynaecologists spokesman said that babies exposed to huge amounts of sugar in the womb continued to make large amounts of insulin after birth.
"A baby getting too much sugar is producing too much insulin. The minute it's born, effectively it is cut off from its mother's sugar supply but keeps on making insulin because its sugar goes too low," the Daily Mail quoted O'Brien as saying.
"Often, these babies have to be fed early or more often they are put on a drip and given glucose," he said.
Others are fed sugar through a tube direct into their stomach.
Gestational diabetes, in which the woman's blood sugar soars, usually develops in the second half of pregnancy and goes away after the baby is born, can have serious consequences for mother and child, including raising the odds of birth defects and stillbirths.
Both mother and child are also at a higher risk of developing full-blown diabetes in later life.
"On average, women are becoming overweight in pregnancy and the more overweight you are the more likely you are to get gestational diabetes," he said.
"The average age of women having babies is older and they are more likely to have diabetes," O'Brien added.
According to health guidelines, mothers-to-be don't need to increase their calorie intake until the last three months, when they need only an extra 200 calories a day, which is the equivalent of a small sandwich or a small bowl of sugar-free muesli.