It is believed that a woman's body weight during pregnancy affects her baby's BMI in the future.
BMI is a measure of body weight that measures height and weight.
Now a new medical study has revealed that the weight of a pregnant woman has less effect on the body weight of the child than expected.
Research published in the medical journal BMC Medicine found that environmental factors are more influential on the body weight of children than the weight of the mother during pregnancy.
Environmental factors such as children's over-eating and lack of exercise affect body weight.
The study, from the University of Bristol in the United Kingdom, collected data from babies born in the 1990's and looked at their body weight between the ages of one year, four years, 10 and 15 years.
The research recruited more than 14,000 pregnant women in the early 1990's.
The results show that there is a slight correlation between the birth weight of the mother and the baby, but this effect also disappears as the baby gets older.
Although the body weight of young people is linked to the mother, it is likely to be the result of hereditary genes and lifestyle factors, the researchers said.
"Children's environment and lifestyle all affect their body weight," he said.
"We all know that lifestyle choices are the foundation of healthy weight, so as a society it is a challenge for us to make healthy choices easier," he said.
But the researchers said the findings did not mean pregnant women should worry about their body weight, in fact maternal obesity could increase other risks.
Overweight women may experience complications such as stillbirth or stillbirth.
Excess body weight also increases the mother's risk of developing diabetes and high blood pressure during pregnancy.
