Pregnancy Problems Tied to Caffeine

Too much caffeine during pregnancy may increase the risk of miscarriage, a
new study says, and the authors suggest that pregnant women may want to
reduce their intake or cut it out entirely.
Many obstetricians already advise women to limit caffeine, though the
subject has long been contentious, with conflicting studies, fuzzy data and
various recommendations given over the years.
The new study, being published Monday in the Journal of Obstetrics and
Gynecology, finds that pregnant women who consume 200 milligrams or more of
caffeine a day - the amount in 10 ounces of coffee or 25 ounces of tea - may
double their risk of miscarriage.
Pregnant women should try to give up caffeine for at least the first three
or four months, said the lead author of the study, Dr. De-Kun Li, a
reproductive and perinatal epidemiologist at the Kaiser Permanente Division
of Research in Oakland, Calif.
"If, for whatever reason, they really can't do it, think of cutting to one
cup or switching to decaf," Dr. Li said. "Stopping caffeine really doesn't
have any downside."
Professional groups like the American College of Obstetricians and
Gynecologists and the American Society for Reproductive Medicine have not
taken official positions on caffeine, representatives said.
On Friday, the March of Dimes Web site said most experts agreed that the
amount of caffeine found in 8 to 16 ounces of coffee a day was safe. It
noted that some studies had linked higher amounts to miscarriage and low
birth weight, but stated: "However, there is no solid proof that caffeine
causes these problems. Until more is known, women should limit their
caffeine intake during pregnancy."
Now, having reviewed the new study, the March of Dimes plans to change its
message, to advise women who are pregnant or trying to conceive to limit
their daily caffeine intake to 200 milligrams or less, said Janis Biermann,
its senior vice president of education and health promotion.
"Women do need good guidance," she said.
Dr. Li's study included 1,063 pregnant women who were interviewed once about
their caffeine intake. At the time of the interview, their median length of
pregnancy was 71 days. But 102 had already miscarried - not surprising,
because most miscarriages occur very early in pregnancy. Later, 70 more
women miscarried, for a miscarriage rate of 16 percent for the group - a
typical rate.
Of 264 women who said they had used no caffeine, 12.5 percent had
miscarriages. But the miscarriage rate was 24.5 percent in the 164 women who
consumed 200 milligrams or more per day. The increased risk was associated
with caffeine itself and not with other known risk factors like the mother's
age or smoking habits, the researchers said.
Dr. Li said the study answered an important question that previous research
had left unresolved. Women who have morning sickness are less likely to
miscarry than those who do not, possibly because the same hormonal changes
that cause nausea and vomiting contribute to a healthy pregnancy. But some
researchers said morning sickness could lead to confusing results in
caffeine studies. These researchers argued that because they feel ill, some
women may consume less caffeine. That tendency may make it appear that they
are less likely to miscarry because they avoid caffeine, when the reason is
actually that they began with healthier pregnancies.
Dr. Li said he and his colleagues had determined that the risk from caffeine
was real and could not be explained away by different rates of morning
sickness.
Dr. Carolyn Westhoff, a professor of obstetrics and gynecology, and
epidemiology, at Columbia University Medical Center, had reservations about
the study, noting that miscarriage is difficult to study or explain. Dr.
Westhoff said most miscarriages resulted from chromosomal abnormalities, and
there was no evidence that caffeine could cause those problems.
"Just interviewing women, over half of whom had already had their
miscarriage, does not strike me as the best way to get at the real
scientific question here," she said. "But it is an excellent way to scare
women."
She said that smoking, chlamidial infections and increasing maternal age
were stronger risk factors for miscarriage, and ones that women could do
something about.
"Moderation in all things is still an excellent rule," Dr. Westhoff said. "I
think we tend to go overboard on saying expose your body to zero anything
when pregnant. The human race wouldn't have succeeded if the early pregnancy
was so vulnerable to a little bit of anything. We're more robust than that."
[NYT]