It has long been thought of as a good idea for expecting mothers to perform some form of aerobic exercise in order to regain their shape after the birth of their baby. However, now a new study into exercise and pregnancy is suggesting that performing aerobic exercise actually helps the baby's health and weight.

The study, at the University of Auckland and published in the Journal of Clinical Endocrinology & Metabolism, found that mothers who exercised regularly during pregnancy gave birth to lighter babies.

The research required the expecting mums to exercise moderately for 40 minutes on a stationary bike 5 times a week up until at least the 36th week of their pregnancy.

The study found that exercising mums gave birth to babies on average 143 grams lighter than those babies of non-exercising women. This news could be significant because babies who are born overweight had been shown to carry a predisposition to become overweight and obese later in their child and adult life.

One point made during the findings was that moderate intensity exercise didn't reduce the amount of insulin resistance - the hormone that regulates blood sugar. It had been thought that in mothers who exercise the insulin resistance could change, which would effect the nutrients being transported to the foetus.