Pregnant women who consume eight cups of coffee or
more per day have double the risk of a stillbirth, compared with women
who drink no coffee during pregnancy, according to a study published in
the Feb. 22 issue of the journal
BMJ,
Reuters/Arizona
Republic reports. Researchers from Aarhus University Hospital in
Denmark based their findings on a study of more than 18,000 women attending
the obstetrics department at the university hospital between 1989 and 1996
who answered questionnaires about their consumption of coffee, alcohol
and cigarettes and their medical history (
Reuters/Arizona Republic,
2/20). According to the study, 31 stillbirths occurred among the 7,878
women who drank no coffee during pregnancy, and 11 stillbirths occurred
among the 950 women who drank eight cups of coffee or more per day during
pregnancy. Therefore, without taking into account other factors, women
drinking eight cups of coffee per day or more had triple the risk of having
a stillbirth; one in 250 pregnancies ended in stillbirth among women who
drank no coffee during pregnancy, compared to three stillbirths for every
250 pregnancies among women drinking eight or more cups of coffee per day
(Wisborg et al.,
BMJ, 2/22). After accounting for medical history,
maternal age, drinking and smoking habits and other factors, the researchers
reported that the risk of stillbirth among the high coffee consumption
group was double that among non-coffee drinkers (
AP/New York Post,
2/21). "Women who have such a high intake of coffee also come with a set
of other characteristics -- like they are more likely to smoke, they have
a higher intake of alcohol, they are older, they've had more pregnancies,
they've had fewer years of education," Lisa Signorello, an epidemiologist
at the
International Epidemiology Institute
and assistant professor of medicine at
Vanderbilt
University, said (Ross,
AP/Arizona
Republic, 2/21). Although the researchers were unsure exactly why
high coffee consumption is associated with an increased risk of stillbirth,
they hypothesized that caffeine could "spark a release of adrenaline which
could contract the blood vessels in the placenta or it may affect the heart
beat" (
Reuters/Arizona Republic, 2/20).
Further Research Needed
According to Alan Leviton, professor of neurology at
Harvard
Medical School, one drawback in the study is that the researchers solicited
information about coffee consumption only once -- at 16 weeks of pregnancy
-- and coffee consumption tends to drop during healthy pregnancies due
to pregnancy signal theory. According to Leviton, women tend to reduce
coffee intake four to six weeks into pregnancy, possibly because elevated
hormones or "signals" made by the placenta cause women to be averse to
the smell. "The inference is that the healthier the placenta, the stronger
the pregnancy signal. The woman who does not have a good implantation of
her placenta doesn't make as many hormones, which puts her at risk of pregnancy
problems such as stillbirth," Leviton said. Under this theory, the fact
that a pregnant woman is able to continue to consume high amounts of coffee
would signal that her pregnancy is already "not going well," according
to the
Associated Press (Ross,
Associated Press, 2/21). The
study authors said that more research is necessary to substantiate the
link between high coffee intake and an increased risk of stillbirth (
AP/Arizona
Republic, 2/21). According to the
Associated Press, previous
studies have linked the consumption of three or more cups of coffee per
day with miscarriage and low birthweight infants (
Associated Press,
2/20). Roger Cook, who is a spokesperson for the
British
Coffee Association, said that pregnant women should not be concerned
by the study's findings. He added that the study's results "do not alter
the advice given to pregnant women by the [British]
Food
Standards Agency who state that 300 mg caffeine -- equivalent to three
mugs or four cups of coffee per day -- is perfectly safe and will have
no adverse effect on the mother or the fetus" (
Reuters/Arizona Republic,
2/20).