Maternal Obesity: Cause, Impact and Intervention

Maternal obesity refers to obesity during pregnancy, that is BMI > 30. It is becoming one of the most commonly occurring high risk factors in current obstetric practice. The prevalence of obesity in the general population as well in pregnancy has increased markedly since 1990s. Factors causing maternal obesity include PCOS, genetic predisposition, familial tendency as well as our current lifestyle and technology which has brought about a change in diet and decreased physical activity. Obesity is classified into

  • Obese (Class I) – BMI in range 30.0-34.9
  • Obese (Class II) – BMI in range 35.0-39.9
  • Extreme obesity (Class III) – BMI 40.0 and higher

Impacts of Maternal Obesity on Mother and Child

Obesity in pregnancy is associated with the number of adverse outcomes, like miscarriages, congenital anomaly, preeclampsia, gestational diabetes, overweight babies or macrosomia(defined as an estimated fetal weight >=4500 g), blood clots, wound infection, still birth, neonatal death.

Obesity not only affects the women but also has adverse effect on the future life of the baby born to such woman. The most important effect of maternal obesity is that intrauterine exposure to maternal obesity is associated with an increased risk of developing obesity and metabolic disorders during childhood. Thus “obesity starts in the womb” holds good for the babies born to obese women. Children from obese mothers have an increased risk of an adverse childhood cardio-metabolic risk profile, including high BP, high abdominal fat mass, high insulin and triglycerides levels and low HDL-cholesterol level. A higher pre-pregnancy BMI combined with increased gestational weight gain may affect respiratory outcomes throughout childhood. Maternal PGDM together with severe maternal obesity increases the risk of psychiatric and mild neurodevelopmental disorders in children. The association of maternal obesity and reduced breast feeding rates, both in terms of initiation and duration is well documented. In such cases, as more bottle-fed, babies tend to be overweight and also result in infant and childhood obesity. The concordance between maternal and childhood obesity stems from other factors like shared genetic risk factors as well. Maternal obesity in particular has been associated with large-for-gestational age babies and increased risk of obesity in adulthood, thus generating a vicious cycle. This shows how obesity can affect one generation to future generation and hence marks the importance to control obesity in the pre pregnancy period. Women need to be educated and made aware of the increased risks associated with obesity and encouraged to optimize their weight before embarking on pregnancy.


Preconception advice and care is the ideal scenario for women with obesity that is BMI > 30, but those obese women presenting for the first time during pregnancy should be given an early opportunity to be aware of the importance of healthy eating and appropriate exercise during pregnancy to prevent excessive weight gain and development of gestational diabetes. If BMI is more than 40 according to Royal College of Obstetricians and Gynaecologists is an indication for bariatric surgery.

Dietary intervention up to a certain extent does help in reducing gestational weight gain as well as some of the obstetric complications such as preeclampsia, gestational hypertension, preterm delivery and the risks of shoulder dystocia of the fetus. The most common diet evaluated was a balanced calorie regime with low fat or cholesterol and high fibre. Interventions are to be provided in both primary and secondary care. Physical activity usually involves having moderate exercise with low-intensity resistance training. Weight management interventions help reduce the chances of having large babies.

Counseling, nutrition and physical activity

Obstetricians must counsel their obese patients regarding the risks and complications associated with obesity and the importance of weight loss. Mother and child surveillance is of utmost importance during pregnancy. Women have to be told about both maternal and fetal complications and the steps necessary to optimize outcome, but the issue of weight prior to pregnancy is the most important fact that needs to be addressed. Modification of lifestyle which include diet habits and physical activity is an effective strategy for improvement of maternal metabolism and the prevention of adverse outcomes

We need to adopt an ecological approach that raises awareness of the importance of good health in the period before pregnancy to reduce chances of maternal obesity.

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