Taking moderate-intensity exercise three times a week during the second and third trimester of pregnancy halves the risk of having a high birth weight newborn (babies with macrosomia, that is, weighing over 4 kilos) and, therefore, the risk of needing a caesarean delivery.

These findings come from research led by Rubén Barakat of the Polytechnic University of Madrid, Alejandro Lucía of the European University of Madrid, and Jonatan Ruiz of the University of Granada. Together with Sports Science graduates, they ran a series of programmed training sessions for a sample of 510 sedentary pregnant women. The results of their study have been published in the British Journal of Sports Medicine.

The researchers contacted a total of 780 Spanish pregnant women attending two primary health care centres in Leganés (Madrid). Finally, 510 gave their consent to participate in the study. They all recognized they were sedentary -- that is, that they exercised for less than 20 minutes on fewer than 3 days a week.

55 minutes exercise

The intervention group followed a training program that consisted of 55 minute sessions of aerobic, muscle strength and flexibility exercises on three days a week from weeks 10-12 to weeks 38-39 of pregnancy, while the control group received standard recommendations and care.

The results showed the training sessions did not reduce the appearance of gestational diabetes mellitus but did diminish the incidence of two major associated risks: macrosomia (down by 58%) and caesarean delivery (which fell by 34%).

These findings "reinforce the need to encourage more supervised exercise interventions during pregnancy to combat the negative effects of gestational diabetes mellitus," says Jonatan Ruiz, researcher in the University of Granada Department of Physical and Sports Education and corresponding author of the study.