Obesity in Pregnancy

By Dr. Ananya Mandal, MDReviewed by April Cashin-Garbutt, MA (Editor)

Studies show that obesity affects several walks of the population at all ages. With the rise of obesity and its associated health problems like heart disease, diabetes, stroke, hypertension and some cancers, obesity has emerged as a major public health problem.

In the United States, more than one third of women are obese according to the recent National Health and Nutrition Examination Survey. This means that more than one half of pregnant women are overweight or obese.

Studies reveal that 8% of women in their reproductive age group are extremely obese. Obesity is highest among non-Hispanic black women (50%) compared with Mexican American women (45%) and non-Hispanic white women (33%). This puts them at a greater risk of pregnancy complications.

Obesity screening

The agencies and guidelines thus recommend screening women for obesity before they conceive. The Institute of Medicine defines obesity classifications as:-

• normal weight - BMI (Body mass index) of 18.5 to 24.9 Kg/m2
• overweight - BMI of 25 to 29.9 Kg/m2
• obesity - BMI of 30 Kg/m2 or greater

Class I obesity includes BMI between 30 to 34.9 Kg/m2 and Class II obesity includes BMI of 35 to 39.9 Kg/m2 whereas Class III obesity is BMI of over 40 Kg/m2.

Possible pregnancy complications due to obesity include risks to the mother while pregnant; risks to the mother during delivery and risks to the baby.

Risks to the mother while pregnant

• Gestational or pregnancy diabetes mellitus.
• Pregnancy induced high blood pressure or hypertension.
• Risk of preeclampsia.
• Risk of deficiencies in iron, vitamin B12, folate, vitamin D, and calcium while pregnant. This is seen among women who need nutrition counselling due to bad eating habits as well as in women who have undergone weight reduction surgeries before getting pregnant.

Risks to the mother during delivery

• Increased incidence of Caesarean delivery. The caesarean delivery rate for example is 20.7% for women with a BMI of 29.9 or less, 33.8% for women with a BMI of 30–34.9, and 47.4% for women with a BMI of 35–39.9.
• Risk of complications during and after delivery.
• Risk of arrest of labour and difficult labour.
• Risks associated with anaesthetic complications.
• There is also an increased risk of wound infections and failure to heal rapidly after a caesarean delivery.
• Risk of thromboembolism or dislodgement and formation of blood clots that travel and block leg veins or those in lungs and brain leading to life-threatening complications. Pneumatic compression devices and unfractionated heparin or low molecular weight (LMW) heparin in such patients is necessary according to estimation of risk.

Risks to the baby

• High risk of the baby being born premature or stillborn.
• High risk of spontaneous abortion.
• High risk of the baby born overweight with high risk of birth injuries.
• The mother’s obesity may also make it difficult for the radiologist to predict and estimate the weight of the fetus within the mother’s womb.
• High risk of the baby having congenital abnormalities.
• High risk of the baby having childhood obesity as it grows.
• Obese women are also less likely to initiate and sustain breastfeeding.

Further Reading

• All Obesity Content
• What is Obesity?
• Causes of Obesity and Overweight
• Obesity, What Can be Done?
• What is Body Mass Index (BMI)?