I think everyone knows the old adage that pregnant women are “eating for two” is not only wrong but positively unhealthy. Yesterday in the British Medical Journal, Shakila Thangaratinam and colleagues published an analysis of papers designed to see if interventions to control maternal weight in pregnancy improved the outcome both for the mother and her baby. This paper reviewed 44 randomised trials involving 7278 women.
The interventions in the studies typically involved introducing a balanced diet and/or introducing walking for 30 minutes or light intensity resistance training. Some studies also introduced behavioural modification for women with problems of binge eating.
The findings suggest that “dietary intervention” reduced maternal weight gain by the order of about 4 kg. This in turn reduced complications in pregnancy such as high blood pressure, diabetes and preterm delivery. Perhaps not surprisingly these interventions helped overweight women most.
The diets usually comprised of 30% fat, 15-20% protein and 50-55% carbohydrate.
There are problems with this study. It pools lots of studies into one pot – and so it is open to bias. A bigger issue is that it is not possible to know whether it is the actual weight loss or the nature of the intervention that improves outcome. In other words it might be the introduction of different food in itself rather than the weight loss caused but the change in diet that improves outcomes. This is important if we are to understand how to best manage patients.
Irrespective of these limitations these data confirm the view that pregnant women – especially if they are overweight – should be encouraged to follow a careful diet in pregnancy from early on and to avoid gaining too much weight. It is also important for pregnant women to understand that exercise in pregnancy is a good thing as long as it is not taken to extremes.