How much weight a woman gains during the first half of pregnancy has been found to play a bigger role in determining her baby's weight than the kilos she puts on closer to the birth.
While some previous studies have shown that general weight gain by mums-to-be during pregnancy affects a baby's weight at birth, a new study by Canadian researchers suggests that the increases during the first 18 weeks are key.
They found that for each kilo a woman gains during the first 14 weeks of pregnancy, a baby's birth weight increases by an average of 13.6 grams.
Weight gained between 14 and 18 weeks has an even bigger impact, with babies' birth weights increasing by 26.1 grams for every kilo gained by the mother-to-be.
However, weight gained by the mother during the second half of pregnancy doesn't have the same impact on a baby's birth weight, the researchers from Canada's Mount Sinai Hospital found.
The researchers based their findings on a study of weight gained by 1164 pregnant women in China between 2009 and 2015.
The latest findings follow a study by Australian researchers published in June found that three quarters of women either gain too much or too little weight during pregnancy.
Pregnant woman who don't put on enough weight are considered by medical experts to be at risk of delivering smaller babies and going into labour early.
Those who gain too much weight are also considered more likely to have bigger babies and need a caesarean.
GUIDELINES FOR HEALTHY WEIGHT GAIN DURING PREGNANCY
* Underweight women should gain 12.5-18kg
* Healthy weight women should gain 11.5-16kg
* Overweight women should gain 7-11kg
* Obese women should gain 5-9kg
(Source: Department of Health)
