A new study has found that taking exercise during pregnancy could cut the chances of having an over-sized baby who could be prone to obesity later in life.
Scientists at the University of Auckland in New Zealand found that pregnant women who carried out fitness training on exercise bikes went on to have lighter babies than women who did not exercise.
The lighter babies were no shorter in length and showed no signs of lacking nutrition.
Large birth weight is associated with an increased risk of obesity so the scientists think this could have an effect on children's health when they get older.
Dr Paul Hofman, from the University of Auckland, told the Press Association: "Our findings show that regular aerobic exercise alters the maternal environment in some way that has an impact on nutrient stimulation of foetal growth, resulting in a reduction in offspring birth weight.
"Given that large birth size is associated with an increased risk of obesity, a modest reduction in birth weight may have long-term health benefits for offspring by lowering this risk in later life."
During the trial scientists studied 84 first-time mothers who were either given an exercise programme or were put in a non-exercise "control" group.
The women in the exercise programme took part in cycling sessions on exercise bikes, with a maximum of five 40 minute sessions per week.
They carried on exercising up until at least the 36th week of pregnancy.
All the women were tested for their sensitivity to insulin, the hormone that controls how the body uses sugar, as there have been concerns that exercise during pregnancy could prevent maternal insulin resistance.
It does seem kind of obvious that women who take healthy exercise during pregnancy could influence the health of their baby - just as eating the right foods and not taking drugs or alcohol can also have an effect.
Did you exercise during pregnancy? If so how much?