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Obesity during pregnancy may directly lead to large babies

Obese pregnant women do have a higher risk of birth complications from delivering an overgrown baby, new research shows.

The study by the National Institutes of Health is one of the clearest indications to date that obesity had a direct causal impact on the development of a fetus, which could leads to dire complications for both the mother and the baby.

Fetal macrosomia, categorized as atypically large infants weighing more than eight pounds 13 ounces at birth, increases the mother’s risk for having a c-section and experiencing excessive bleeding as well as the baby’s risk for bone-fracture during delivery. 

As obesity rates in the US continue to rise, findings suggest this not only affects the mother, but leaves children at a greater risk of being obese themselves and developing heart disease later in life.

Obesity during pregnancy may directly lead to overgrown infants, which poses a greater risk for complications with the mother and baby, research from the National Institues of Health found

In 2014, approximately 50 percent of all pregnant women in the United States were overweight or obese. 

Evidence suggests that the recent increase in severe maternal morbidity in the US is related to maternal obesity. According to the CDC, 50,000 women in the United States suffer from SMM and the rate has been steadily increasing.

Severe maternal morbidity is defined as unexpected outcomes of labor and delivery that result in significant short or long-term consequences to a woman’s health.

Those pregnancy complications include, diabetes, high-blood pressure, massive blood loss and c-section.

‘Our results underscore the importance of attaining a healthy body weight before pregnancy,’ said the study’s lead author, Cuilin Zhang, M.D., Ph.D., a researcher from the National Institutes of Health.

Zhang added: ‘They also suggest that clinicians should carefully monitor the pregnancies of all obese women, regardless of whether or not they have obesity-related health conditions.’

Researchers speculate that higher blood sugar levels could prompt overgrowth in obese women’s fetuses. 

Researchers analyzed ultrasound scans taken throughout pregnancy of more than 2,800 pregnant women between 2003 and 2013. Of those women, 443 were obese with no accompanying health conditions, such as diabetes, and more than 2300 were non-obese.

The researchers categorized the women’s weight according to their body mass index or BMI score. Women with a BMI ranging from 30 to 44.9 were classified as obese, while those with a BMI of 29.9 were considered non-obese.

Beginning in the 21st week of pregnancy, ultrasound scans revealed that for the fetuses of obese women, the femur (thigh bone) and humerus (upper arm bone) were longer than those of the fetuses of non-obese women. 

The differences between fetuses of obese and non-obese women continued through the 38th week of pregnancy. 

For fetuses in the obese group, the average femur length was 0.03 inches longer compared to the non-obese group, and humerus length was about 0.04 inches longer.

Average birth weight was about 0.2 pounds heavier in the obese group. Those infants were also more likely to be classified as large for gestational age (birth weight above the 90th percentile). 

The study says: ‘Low and high pre-pregnancy BMI were associated with a statistically significant but small increase in the risk of severe maternal morbidity or mortality.’

Researchers could not determine exactly why the fetuses of obese women were larger and heavier.

But the researchers theorize that because obese women are more likely to experience difficulty using insulin to lower blood sugar, higher blood sugar levels could have promoted overgrowth in their fetuses.

The authors pointed out that earlier studies have indicated that the higher risk of overgrowth seen in newborns of obese women may predispose these infants to obesity and cardiovascular disease later in life. 

They called for additional studies to follow the children born to obese women to determine what health issues they may face.