May 21, 2010

Caffeine In Pregnancy Can Cause Smaller Babies

A new study finds that pregnant women who down six coffee cups' worth of caffeine every day may have smaller babies than those that consume less caffeine.

The team found that among the 7,300 Dutch women studied, between 2 and 3 percent said they consumed the caffeine equivalent of six cups of coffee per day during any trimester.  Their babies' length at birth was slightly shorter on average than that of newborns whose mothers consumed less caffeine while pregnant.

Heavy caffeine consumers also had an increased risk of having a baby who was small for its gestational age.

However, that finding was based on a small number of babies, and the significance is uncertain.  Of 104 infants born to women with the highest caffeine intakes, seven were of small gestational age.

The findings add to the conflicting body of research into whether caffeine during pregnancy affects fetal growth.  The study was reported in the American Journal of Clinical Nutrition.

Some studies have linked regular caffeine consumption during pregnancy to an increased risk of low birth weight.  However, other studies have not found the same effects.  Researchers also found conflicting conclusions as to whether caffeine affects the risk of miscarriage.

Rachel Bakker and colleagues at Erasmus Medical Center in Rotterdam used ultrasound scans in this latest study to monitor fetal growth over the course of pregnancy in 7,346 women.

The women reported on their usual intake of coffee and tea at each trimester.  Most women consumed less than the equivalent of four cups of coffee each day at any point during pregnancy, but between 2 and 3 percent downed six or more cups' worth of caffeine.

Babies born to heavy caffeine consumers were slightly shorter on average during birth and all three trimesters of fetal development.

"Caffeine intake seems to affect length growth of the fetus from the first trimester onwards," Bakker told Reuters Health in an email.

She said the implication is that pregnant women should not consume more than six cups of coffee per day. However, the findings also do not mean that less coffee is generally "safe" during pregnancy.

"We only studied the effect of caffeine on fetal growth," Bakker said. "Future studies on possible other effects of maternal caffeine intake are therefore needed."


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