Weight gain in pregnancy
Why weight gain in pregnancy is kept within a recommended range, what the risks are at either extreme, and how body mass index is calculated.
When weight gain in pregnancy is greater than it should be, the risk of gestational hypertension, pre-eclampsia, gestational diabetes, macrosomia (a large baby) and delivery by caesarean section all increase. The size of that risk is known to depend on how much weight is gained before delivery.
When weight gain is lower than it should be, the risk rises of a baby born with a low weight for its gestational age.
For that reason, weight gain through pregnancy should be kept within the recommended range, with appropriate lifestyle changes, dietary planning and exercise. The recommendations for weight gain in pregnancy are based on the woman's body mass index.
How body mass index is calculated
Body weight in kilograms divided by the square of height in metres (kg/m²).