No matter how tired you get during your pregnancy, a new animal study suggests that countering your fatigue with too much coffee might harm your baby.
Female rats that were given caffeine during pregnancy had offspring with lower birth weights, altered growth and stress hormone levels, and impaired liver development.
How much coffee is too much?
The findings suggest that in pregnant women, consuming an amount of caffeine equivalent to 2 to 3 cups of coffee a day may change stress and growth hormone levels in a way that can impair infants' liver growth and development. It may also increase their risk of liver disease in adulthood.
"Our work suggests that prenatal caffeine is not good for babies and although these findings still need to be confirmed in people, I would recommend that women avoid caffeine during pregnancy," said study co-author Yinxian Wen, from Wuhan University in China.
The study was published recently in the Journal of Endocrinology.
Previous studies have indicated that consuming 2 to 3 cups coffee a day during pregnancy can result in lower infant birth weight.
Animal studies have also suggested that caffeine consumption during pregnancy may have long-term harmful effects on liver development leading to increased susceptibility to non-alcoholic fatty liver disease, a serious condition normally associated with obesity and diabetes.
While this study in rats provides new insight, the findings need to be confirmed in humans.
Rats in the study that were exposed to caffeine in the womb had lower levels of the liver hormone insulin-like growth factor 1 (IGF-1), and higher levels of the stress hormone corticosteroid at birth.
These rats also had a "catch-up" phase of liver development after birth, characterized by increased levels of IGF-1.
"Our results indicate that prenatal caffeine causes an excess of stress hormone activity in the mother, which inhibits IGF-1 activity for liver development before birth," Wen said in a journal news release.
"However, compensatory mechanisms do occur after birth to accelerate growth and restore normal liver function, as IGF-1 activity increases and stress hormone signaling decreases," Wen said. "The increased risk of fatty liver disease caused by prenatal caffeine exposure is most likely a consequence of this enhanced, compensatory postnatal IGF-1 activity."
The March of Dimes has more on caffeine in pregnancy.