What is BMI and How Does It Affect Pregnancy?

5 mins read

BMI is an abbreviation for body mass index, and it refers to an individual’s body weight in relation to his or her height. It is calculated by dividing a person’s weight in kilograms by his or her height in meters squared, and it is used to measure a person’s body fat. A higher BMI means higher body fat content. BMI determines whether someone is extremely obese, obese, overweight, normal weight, or underweight. It can be measured at any health facility. 

Calculating BMI is pretty easy. If you are using the International System of Units (SI), the first step is to multiply your height in meters by itself. So, if your height is 1.6 meters, then 1.6 × 1.6 = 2.56. Next, divide your weight in kilograms by the answer in step one. If your weight is 73.2 kg, then  73.2 ÷ 2.56 = 28.59. Your BMI is 28.59. 

If you are using the US customary system, you need to first convert your height into inches and then multiply your height in inches by itself. For instance, if you are 70 inches tall, then 70 × 70 = 4900. Divide your weight into pounds by the previous answer. If you weigh 155 pounds, then 155 ÷ 4900 = 0.03163. Next, multiply your answer by 703:  0.03163 × 703 = 22.23. Your BMI is 22.23. Normal BMI will fall between 18.5 and 24.9. Anything above 24.9 indicates that you are overweight, and anything below 18.5 indicates that you are underweight.

Effects of BMI on Pregnancy

Women with low BMI are mostly at risk for premature birth and giving birth to underweight children. With monitoring and assessment, they may be able to gain adequate weight during their pregnancy.

The higher the BMI is, the higher the chances of contracting health disorders and illnesses, such as high blood pressure, high cholesterol, stroke, diabetes, and heart disease. These conditions will, in turn, affect the unborn child. The child has a higher risk of developing abnormalities or defects. High BMI in pregnancy also causes miscarriages and premature births. 

In addition, high BMI may cause prolonged labor that is unusual and extremely painful. Studies show that women with high BMI have difficulties pushing and may need emergency operations. Furthermore, the wounds will take a lot longer to heal, so there is a higher risk of postpartum bleeding. Mothers also risk having a stillbirth, or the child could be born overweight (above 4 kg) and have an increased risk of developing obesity and diabetes in life.

Solutions to High BMI in Pregnancy

Healthy eating can help reduce BMI considerably. Food portions should be small and evenly spread out throughout the day. The mother’s diet should mainly consist of whole grains, foods low in fat, fiber-rich foods, and more fruits and vegetables. Exercise and physical activity can boost the mother’s metabolic rate. Walking, swimming, light aerobics, and even cycling are exercises that women can do while pregnant. Supplements, such as folic acid and vitamin D, can help the baby’s development. Supplements also help to strengthen the mother’s muscles and boost cell activity. Regular prenatal checkups will help detect potential pregnancy disorders. Disorders like thrombosis, preeclampsia, and diabetes can be managed if diagnosed in time. Plan the birth as much as possible, including where it will be and the doctor who will attend the birth, so that everyone is prepared in case of complications.


Adequate prenatal care can provide support and guidance during pregnancy. Expert advice will benefit both the mother and the child. Talking to other pregnant women may also help mothers gain support and learn more information about pregnancy and birth.


  • Bhattacharya, Sohinee, Doris M. Campbell, William A. Liston, and Siladitya Bhattacharya. “Effect of Body Mass Index on Pregnancy Outcomes in Nulliparous Women Delivering Singleton Babies.” BMC Public Health 7 (2007): 168.
  • Sirimi, Natalia, and Dimitrios G. Goulis. “Obesity in Pregnancy.” Hormones 9, no. 4 (2010): 299–306.

Leave a Reply

Your email address will not be published.

This site uses Akismet to reduce spam. Learn how your comment data is processed.

Latest from Blog