Scientists have always been unsure about commenting on whether weight gain during pregnancy actually plays a role in determining a baby's weight at birth.

For finding this data from 513,501 women who had two or more live births was examined by researchers at Children's Hospital Boston.

The total number of babies in the study were more than 1.1 million. Birth weight among siblings was compared to pregnancy weight gain to control for genetic influences.

It was then noticed that a mother's weight gain during pregnancy definitely played a role the baby's weight.

Women who gained more weight had heavier babies.

Excessive pregnancy weight gain leads to various problems like increased risk of diabetes and obesity and complications during delivery.

It is dangerous for babies also as having more weight at birth might lead to more weight later on also. Mothers should keep a watch on their pregnancy weight.

Dr. David Ludwig said, "Hormones and metabolic pathways, and even the structure of tissues and organs that play a role in body weight maintenance are affected."