You are here

Moms' Pre-Pregnancy Weight Impacts Baby's Size


Although most moms know that weight gain during pregnancy can impact the birthweight of their baby, they may not know that their pre-pregnancy weight can also influence their baby’s size at birth—but a new study published in the journal Acta Obstetricia et Gynocologica Scandinavica (AOGS) has found just that, reports ScienceDaily. These findings are particularly important given new research indicating that high birthweight may also predict higher-than-average weight in children and adults.

Plus: Does Obesity Begin in the Womb?

Researchers in Norway studied more than 58,000 women and found that the higher a woman’s body mass index (BMI) before she got pregnant, the bigger her newborn. The average weight of the babies born to the skinniest moms was a pound less than the babies born to the heaviest moms.

Plus: Calculate Your BMI

"Encouraging women to attain a healthy weight before conception and keep a moderate weight gain during pregnancy is important to avoid high or excessive birthweight in offspring," said the study’s lead researcher, Dr. Unni Mette Stamnes Koepp.

Plus: How to Get Pregnant Faster

On the bright side, if one is overweight, reaching a healthy pre-pregnancy weight allows for a bit more leeway in pregnancy weight gain (and actually ups one’s chances of getting pregnant in the first place). Current guidelines for pregnancy weight gain with a single baby, based on a woman’s BMI before becoming pregnant, are as follows:

  • Underweight (with a BMI of 18.5 or lower): Gain 28-40 pounds
  • Normal weight (with a BMI of 18.6 to 24.9): Gain 25-35 pounds
  • Overweight (with a BMI of 25 to 29.9): Gain 15-25 pounds
  • Obese (with a BMI of 30 or higher): Gain 11-20 pounds 

Were you at a healthy weight when you got pregnant? Do you think it impacted the size of your baby?