The findings, experts say, don't give the OK to heavy caffeine intake during pregnancy or breastfeeding. But they are in line with research suggesting that moderate amounts of caffeine may not pose a danger.

Small studies over the years have come to mixed conclusions on whether caffeine during pregnancy was linked to increased risks of miscarriage or premature birth.

But more recently, larger studies have failed to show any heightened risk. And in 2010, the American College of Obstetricians and Gynecologists (ACOG) said that 200 milligrams of caffeine a day -- about the amount in a 12-ounce cup of coffee -- probably did not carry pregnancy risks.

But not much has been known about whether caffeine, during pregnancy or breastfeeding, might disturb new babies' sleep.

For their study, Dr. Ina Santos and her colleagues at Federal University of Pelotas, in Brazil, interviewed 885 new moms. The women answered questions about their caffeine intake and their infants' sleep habits at the age of three months.

All but one of the mothers said they drank caffeinated beverages during pregnancy. About 20 percent were considered heavy consumers during pregnancy -- downing at least 300 mg per day. And just over 14 percent reported a heavy caffeine intake three months after giving birth.

Overall, the researchers found no clear link between moms' caffeine intake and their likelihood of reporting infant sleep problems.

Almost 14 percent of mothers said their three-month-old woke up more than three times each night -- which was considered "frequent."

But the odds were not statistically greater for moms who were heavy caffeine consumers, versus lighter consumers, Santos's team reports in the journal Pediatrics.

"I think this report adds to the growing body of literature suggesting that moderate caffeine consumption during pregnancy is generally safe," said Dr. William H. Barth Jr., chief of maternal-fetal medicine at Massachusetts General Hospital in Boston.

Barth, who was not involved in the study, chaired the ACOG committee that wrote the 2010 report.

While heavy caffeine consumers in this study got 300 mg or more per day, "I don't think this report is too different from ACOG's recent committee opinion," Barth told Reuters Health in an email.

He said the bottom line for women is that moderate caffeine intake -- up to a cup or two of coffee per day -- seems safe during pregnancy.

"However," Barth said, "we do not know if there are adverse effects of higher levels of caffeine consumption."

As for breastfeeding, it's generally thought that 300 mg of caffeine or less each day is OK, according to Dr. Lauren Hanley, an obstetrician at Mass General who specializes in breastfeeding issues.

That's the case for healthy, full-term babies at least, Hanley told Reuters Health in an email.

But preterm infants and newborns metabolize caffeine more slowly, and may be more sensitive to the small amount of caffeine that passes into breast milk.

And studies suggest that high amounts of caffeine during breastfeeding -- "much higher" than 300 mg per day, Hanley said -- are related to "jitteriness," fussiness and poor sleep in babies.

Coffee is, of course, not the only source of caffeine. The 200- to 300-mg limit suggested for pregnant or breastfeeding moms would also translate to about four 8-ounce cups of tea or five 12-ounce cans of soda a day.

SOURCE: bit.ly/Hf4y9Y Pediatrics, online April 2, 2012.

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