Obesity secondary to adverse lifestyle presents a major public health and economic burden worldwide. Established obesity requires intensive, multidisciplinary and costly treatment. Once obesity is established, lifestyle induced weight loss is largely unsustainable due to physiological adaptation which drivesweight regain. In contrast, prevention of weight gain is feasible with minor lifestyle changes and small energy balance adjustments (220kJ/day), conveying long term health benefits. In this context, the World Health Organization (WHO) global strategy for the prevention of non-communicable diseases notes obesity as a preventable condition and recommends to aim to increase physical activity and improve diet to prevent obesity. This is therefore now a high priority internationally.pregnant woman

The health implications of weight gain are major and the risks increase with each kg gained across all weight categories, making prevention a priority for all women. Diabetes risk increases above BMI of 22 kg/m2 with 18% affected in normal weight, 35% in overweight and 75% in obese women. Cardiovascular disease is the number one cause of mortality from non-communicable disease inwomen and increases by 3% for each kilo gained. As 55% of deaths are lifestyle or weight related, the imperative for effective obesity prevention interventions is critical.

Pregnancy is a key driver ofweight gain,withmostwomen in developed countries exceeding recommended gestational weight gain (GWG) with a mean 2–5 kg retained per pregnancy. Excess GWG is directly related to long-term obesity across all weight categories.

Pregnancy therefore offers significant opportunities for obesity prevention and reproductive aged women are now targeted as a high risk group with recommendations to limit GWG and encourage postpartum weight loss. In additional to driving maternal obesity, excess GWG also worsens pregnancy complications for both mothers and babies.

Individual behavior change, ideally enabled by societal and environmental change is needed to prevent and manage obesity. Adopting healthy lifestyle interventions in pregnancy with positive changes to dietary intake and physical activity prevents excess GWG gain and may reduce pregnancy complications based on systematic review and meta-analysis. 

Preconception Intervention Opportunities to Prevent Weight Gain

Most women do not engage in maternity care until late in their first trimester. Therefore, pre-conception offers an opportune time for screening for risk factors that may impact on fertility, pregnancy and the future child. The preconception period provides an opportunity to assess for and manage weight associated maternal chronic conditions including diabetes, hypertension, sleep apnoea and polycystic ovary syndrome. It is also an ideal time to discuss and offer an individualized diet and physical activity as weight loss pre-conception will improve fertility and pregnancy outcomes in overweight or obese women. Diet and physical activity pre-conception may also improve GWG. Pre-conception are also associated with trends in decreased GWG.

Adverse Health Outcomes of Excess Maternal GWG

In the US, Europe and Australia, 20–50% of women gain more than the recommended GWG during pregnancy. Every kilo above recommended, linked to 10% increase in adverse outcomes: including pre-term birth and caesarean section. Other outcomes are more debated, including gestational diabetes (GDM) and gestational hypertension/pre-eclampsia. Short-term infant outcomes include increased birth weight.

Recommendations for Optimal GWG 1

  • Healthy GWG is not equal across the BMI spectrum. All guidelines allow greater GWG in women who are underweight at the onset of pregnancy. 2.
  • Underweight women can have high GWG without the consequences of adverse maternal and infant outcomes, hence their weight gain allowance is more generous. 3.
  • Most guidelines recommend lower weight gain for overweight and obese women, and across ethnicities, these women are more likely to exceed recommended weight gain, even though their mean weight gain during pregnancy is less than normal weight women.

BMI categories (kg/m2)

Proposed optimal CWG  Weight in kg       
BMI categories (kg/m2)        
Underweight <18.5 12.5-18 4-10* 8-25  9.5 (12.9 to 23.9)***
Normal weight 18.5-24.9 11.5–16 2–10* 2–18 13.7 (7.7 to 18.8)**
Overweight 24.9–29.9 7-11.5 <9 -7 to 12 7.9 (2.6 to 14.0)**
Obese ≥ 30 5-9.0 <6 15 to 2 21.8 (-5.0 to 7.0)**

*BMI cutoff of 20.

**BMI cutoff of 18.5 to < 23 for normal weight; 23 to < 27.5 for overweight; 27.5 for obese.

***Numbers in paraenthesis represent the lower and uppermarkings of the GWG range for which aggregated risk of composite adverse outcome does not exceed a 5% increase from the lowest aggregated risk.pregnant women doing yoga

Lifestyle Interventions and the Need for More Research

Prevention of obesity is important for all lifelong. In this context, targeting pregnant women in prevention of weight gain is important as:

  • there are significant reproductive implications of obesity;
  • many women now exceed international GWG recommendations and 2–5kg are retained per pregnancy;
  • pregnancy offers a defined life stage for women captured in our existing health system with enablers for lifestyle change;
  • healthy lifestyle change in pregnancy improves outcomes;
  • weight gain during pregnancy contributes significantly to maternal obesity with potential for long term health benefits;
  • women influence family lifestyle with maternal lifestyle changes having broader implications for families and communities.

prevention of obesity present a major and neglected public health burden. Reproductive aged women are a recognized high risk target group for weight gain and related complications. Excess GWG is a significant contributor to obesity in women which carries independent increased risks of adverse maternal and infant outcomes, including and not limited to caesarean section, increased birth weight, LGA and long term maternal and childhood obesity. Further research is required to assist in refining and optimizing GWG recommendations across different BMI categories and ethnic groups. Individually targeted antenatal lifestyle interventions effectively limit excess GWG, contributing to prevention of obesity in reproductive aged women. Specific maternal and neonatal pregnancy benefits of these interventions still require clarification. Optimal components of antenatal lifestyle interventions as well as the cost effectiveness of these interventions are currently being researched through an international individual patient data meta-analysis of lifestyle interventions in pregnancy that will guide practice and policy in this area. We then require pragmatic implementation strategies to scale up healthy lifestyle into routine antenatal care.

Ultimately, antenatal interventions need integration with prevention efforts across the life stages including in childhood and adolescence and preconception to prevent maternal weight related pregnancy complications. While ultimately healthy lifestyle is a matter of individual behavior change, individual interventions must extend beyond individual targeted initiatives to address societal and environmental factors and enable children, adolescents andwomen to have a healthier lifestyle and to prevent obesity and related complications.