April 2, 2012 — Heavy consumption of caffeine by pregnant or nursing women did not cause sleep interruptions in their infants at 3 months of age, according to a study published online April 2 in Pediatrics.
Iná S. Santos, MD, PhD, from the Federal University of Pelotas, Brazil, and colleagues analyzed the records of all children born in 2004 in the city of Pelotas. Mothers were interviewed just after giving birth, when children were also examined, and the mothers were interviewed again when the children were 3 months old.
The focus of the interviews was to obtain information on consumption of caffeine by the mothers and its potential effect on the children's sleep. Heavy consumption of caffeine was defined as 300 mg/day or more. Caffeine sources included instant and ground coffee and mate, a hot, tea-like beverage popular in the Pelotas region of Brazil.
The amount of caffeine in coffee can vary, but multiple sources indicate that an 8-oz cup of generic brewed coffee contains 95 to 200 mg of caffeine, and an 8-oz cup of instant coffee contains 27 to 173 mg of caffeine.
A total of 4231 children were born in Pelotas in 2004, and researchers gathered information on child sleeping experiences on a subset of 885 infants, with a high proportion of them from wealthier families and from mothers with higher education levels.
Only 1 of the mothers reported no caffeine consumption during pregnancy. Others reported consuming decreasing amounts as gestation progressed, from 178 mg/day during the first trimester to 166 mg/day during the third trimester. At 3 months after birth, they reported an average consumption of 144 mg/day. The prevalence of mothers reporting heavy caffeine consumption progressively decreased, from 24.1% (95% confidence interval [CI], 21.2% - 27.1%) during the first trimester to 20.3% (95% CI, 17.6% - 23.1%) in the third trimester, and to 14.3% (95% CI, 12.0% - 16.6%) 3 months after birth.
"Maternal caffeine consumption, even in large amounts during gestation and lactation, had no consequences on sleep of the infant at 3 months of age," the researchers write. "The reason for no association is not clear. It is possible, however, that infant[s] from heavy consumers develop tolerance to caffeine."
According to the study results, prevalence of frequent nighttime awakenings amounted to 13.8% (95% CI, 11.5% - 16.0%) among the subset population of infants, and the quality of sleep was considered regular or poor by the mothers of 11.1% of the infants.
The prevalence of awakenings was higher for boys than for girls, and higher for children of nonwhite mothers and children whose mothers smoked and consumed alcohol during pregnancy.
The investigators controlled for maternal age, skin color, parity, smoking, alcohol consumption, child’s sex, and family income. In adjusted analyses, heavy consumption of caffeine was not associated with frequent infant night waking. Although mothers who were heavy consumers during the third trimester and postpartum reported increased prevalence of night awakenings, the ratio was not significant.
The researchers also evaluated the effect of caffeine on children's crying and colic at 3 months of age for the entire population (3985 infants), as well as frequent night waking at 1 year old (3907 infants). The authors found no association in proportional decreases in awakenings until about 6 months of age, then an increase from 6 to 9 months, and then a decrease at 12 months.
The researchers did not distinguish between crying night awakenings that were attended to by mothers and noncrying awakenings in which the infants fell back asleep without parental attendance. "So it is possible that some noncrying awakenings may have passed unnoticed to non-bed-sharing mothers in Pelotas," the researchers write.
The authors have disclosed no relevant financial relationships.
Pediatrics. Published online April 2, 2012. Abstract
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