Bigger Isn't Better with a Baby

Pregnancy risks while overweight or obese increased for various complications

/ Author:  / Reviewed by: Robert Carlson, M.D Beth Bolt, RPh

(RxWiki News) A woman's weight before she becomes pregnant can contribute to how her pregnancy plays out, regardless of how much weight she gains while pregnant.

A recent study found that the risks for various pregnancy complications were greater for women who were overweight or obese.

Overweight, obese and severely obese women were at greater risk for high blood pressure and gestational diabetes compared to women of a normal weight.

Overweight and obese women were also more likely to need a cesarean section and to have more hospital admissions.

This increased care also meant higher costs for the women who were overweight or obese.

"Attend all prenatal appointments."

The study, led by Fiona Denison, MD, of the MRC Center for Reproductive Health at the University of Edinburgh in Scotland, looked at the effects of women's weight on their pregnancy outcomes.

The researchers investigated 124,280 deliveries of single babies that were born to 109,592 women in Scotland between 2003 and 2010.

All the women's records included their body mass index (BMI) before their 16th week of pregnancy. 

BMI is a ratio of a person's height to weight and is used to determine how healthy a person's weight is. 

A person with a BMI between 18.5 and 25 is considered of a normal weight. Underweight is a BMI less than 18.5, and an overweight BMI is between 25 and 30. An obese person has a BMI between 30 and 40, and a severely obese BMI would be a 40 or greater.

The researchers found that women who were overweight, obese or severely obese had significantly greater risks for various complications when compared to women of normal weight.

Compared to women of normal weight, overweight women were 1.9 times more likely to experience high blood pressure and were 1.8 times more likely to experience pregnancy-induced high blood pressure.

Obese women were 12 times more likely and severely obese women were 36 times more likely to experience high blood pressure in general.

Obese women were three times more likely and severely obese women were 4.5 times more likely to experience pregnancy-induced high blood pressure, compared to normal weight women.

The risks for gestational diabetes were 3.4 times greater for overweight women, 12 times greater for obese women and 67 times greater for severely obese women.

The chances of needing an emergency cesarean section were 1.9 times greater in overweight women, 3.4 times greater in obese women and 14 times greater in severely obese women.

In addition, women who did not have a healthy pre-pregnancy weight were much more likely to have additional hospital admissions and longer hospital stays.

Underweight women had a slightly higher rate (8 percent) of hospital admissions than normal weight women, while overweight women had a 16 percent higher number of admissions.

Obese women had a 45 percent greater number of admissions than those with a normal weight, and severely obese women had an 88 percent greater number of admissions than those with a normal weight.

The increases in women's length of stay in the hospital when overweight was less dramatic.

Overweight women tended to stay an average 4 percent longer in the hospital, compared to normal weight women, while obese women stayed 9 percent longer and severely obese women stayed 12 percent longer.

The greater level of care for complications, hospital admissions and length of stay translated into greater costs for women who were not a normal weight.

"Weight gain during pregnancy, like weight gain when not pregnant needs to be monitored," said Andre Hall, MD,  an OBGYN at Birth and Women's Care, PA in Fayetteville, NC.

"Unfortunately, pregnancy is often used as an excuse to give in to cravings and to gain weight unchecked," he said. "This is a mistake as excessive weight gain during pregnancy increases a woman's chance of developing hypertension during pregnancy, gestational diabetes, and abnormally large infants."

He said these complications then increase other risks.

"These large infants are at greater risk for birth injuries during delivery," Dr. Hall said. "Women should attend their prenatal visits and work diligently to follow instructions for appropriate weight gain."

This study was published September 18 in BJOG: An International Journal of Obstetrics and Gynaecology. The research was funded by a Chief Scientist Office Grant. The authors declared no conflicts of interest.

Review Date: 
September 20, 2013
Last Updated:
September 24, 2013