Moderate caffeine intake during pregnancy may impact infants' size at birth

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Experts say that caffeine can affect fetal stress hormones

Giving up coffee during pregnancy can be difficult for many women. Now, researchers from the National Institute of Health (NIH) are exploring the risks associated with women can’t kick that caffeine habit during pregnancy. 

According to their findings, even moderate caffeine consumption during pregnancy can affect newborns -- particularly when it comes to birth weight and height. The researchers learned that having as little as half a cup of coffee every day during pregnancy can impact infants’ size at birth. 

Cutting back on caffeine

For the study, the researchers analyzed health outcomes from more than 2,000 women who enrolled in the study during their first trimesters. The women reported on their caffeine intake, including quantity and the type of caffeinated beverages, and gave blood samples for the researchers to analyze for caffeine levels. When the women eventually gave birth, the researchers compared women’s caffeine intake with their infants’ birth weight. 

Ultimately, women’s caffeine consumption during pregnancy had a direct impact on their children’s size at birth. The study showed that even low levels of caffeine during pregnancy led to smaller babies in nearly every category: weight, height, thigh circumference, and head circumference. 

Compared to women who reported drinking the lowest quantities of caffeine, those who drank around half a cup of coffee each day had infants that were more than two ounces smaller at birth. Similarly,  those with the highest levels of caffeine in their blood had infants that were nearly three ounces lighter and nearly 0.2 inches shorter at birth. 

Consult with your doctor

The researchers believe that caffeine directly affects newborns’ stress levels and the blood supply they receive through the placenta, which is most likely why higher levels of caffeine limited their growth. Moving forward, they recommend that women consult with their doctors about the appropriate levels of caffeine to have during pregnancy. 

“Until we learn more, our results suggest it might be prudent to limit or forego caffeine-containing beverages during pregnancy,” said researcher Dr. Katherine L. Grantz. “It’s also a good idea for women to consult their physicians about caffeine consumption during pregnancy.” 

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