The study, published in the clinical “Obesity” journal, found that pregnancy is not a trigger for significant weight gain in Australian women. 

Although longitudinal studies show that women gain weight in young adulthood, and previous research has concluded that there is a link between having children and long-term weight gain, the study has found no connection.

However, it found that depression and not having a paid job were influencing factors leading to higher weight gain in the long term, while a university education and very high levels of physical activity were protective.

Prof of Midwifery and lead author Deborah Davis says the research shows that there are many interacting factors that might cause weight gain other than pregnancy.

“There is a long-held perception that having babies contributes to women’s weight gain leading to overweight and obesity. We now have found that this is not the case,” she says.

While the direction of the link between depression and weight gain is unclear – whether depression leads to weight gain or weight gain leads to depression – women and health care providers should be aware of the risks.

“Women who had five or more babies in the 16-year study period were significantly heavier than all other women but once other factors were taken into consideration (such as socioeconomic status and education) this difference was not statistically significant,” Prof Davis says.

The research, which sampled more than 8000 young women in Australia over a 16-year period, also found that a university education and high levels of physical activity could be a protective factor against long-term weight gain.

“The levels of physical activity required to protect against becoming overweight and obese in the long term are more than those recommended currently in Australia,” she says.