The incidence of maternal obesity is on the rise, with one in five pregnant women estimated to be obese. This poses great risk for both mother and baby; obese women are more likely to develop gestational diabetes and gestational hypertension than mothers of normal weight, and pregnant women with extreme obesity are at 1.6 times greater risk of suffering a premature birth. Maternal obesity is also associated with  increased risk of miscarriage, congenital abnormalities and long-term health risks for the baby, including autism and obesity in future generations.

The National Institute for Health and Clinical Excellence (NICE) has issued guidance
recommending that healthcare professionals educate women on the health
risks of obesity during pregnancy. Guidance is mainly focused on weight
loss when planning a pregnancy, and it is recommended that women have a
balanced diet combined with an active lifestyle. However, around 50% of pregnancies are unplanned, highlighting the importance of weight-loss interventions during pregnancy.

In a systematic review and meta-analysis published in BMC Medicine,
Oteng-Ntim and colleagues show that lifestyle interventions during
pregnancy are associated with improved pregnancy outcome. The study
analysed published randomised controlled trials (RCTs) and non-RCTs
including individual and group-based dietary and exercise interventions.
The authors found that interventions are associated with a reduction in
maternal weight gain and prevalence of gestational diabetes, suggesting
that interventions during pregnancy are beneficial. However, there were
no significant effects on other outcomes, including caesarean delivery
and birth weight. 

The study by Oteng-Ntim and colleagues shows that lifestyle interventions during pregnancy can be used to reduce adverse maternal outcomes, and highlights that more high-quality trials are needed to assess the effect on infant outcomes. 
Following this insightful study, future research should address whether
following diet and exercise recommendations during pregnancy reduces
birth weight and caesarean delivery; Oteng-Ntim and colleagues showed
that studies investigating these outcomes were of low quality. If future
research yields positive results, interventions targeting obesity in
pregnant women could be offered routinely to improve both maternal and
infant pregnancy outcomes.