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Too much caffeine during pregnancy may increase the risk ofmiscarriage, a new study says, and the authors suggest that pregnantwomen 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 American
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.”

Source: http://www.preventionpays.org/News_PDFs/NYTimesPregnancyStudy.pdf