Coffee may hike miscarriage risk

Drinking a couple of cups of coffee a day has long been considered safe during pregnancy, but a new study finds that even this modest amount of caffeine could double a woman’s risk of miscarriage.

Doctors are split on what this means for pregnant women, with some advising avoiding caffeine altogether and others saying buzz-inducing beverages are still safe in moderation.

Previous studies have linked caffeine to an increased risk of miscarriage, but they have focused on higher doses and the connection has been controversial, with some experts arguing that the research didn't account for morning sickness. The nausea and vomiting of morning sickness, caused by elevated hormones, is generally a sign of a reduced risk of miscarriage — and also can lead women to stop drinking their usual coffee or other caffeinated drinks. The concern was that the cutback in caffeine among these women could make it appear caffeine was associated with miscarriageTo get to the bottom of this puzzle, a team
led by Dr. De-Kun Li, a researcher at Kaiser Permanente in Oakland,
Calif., conducted one of the first studies to take into account morning
sickness. They concluded that a daily habit of drinking 200 milligrams
of caffeine — the amount typically found in just two cups of coffee —
significantly increases the risk of miscarriage.

“If
women become pregnant or are actively planning to become pregnant they
should probably think about stopping drinking caffeine, at least during
the first trimester when most miscarriages occur,” Li said.

“If they really have to drink, they should probably limit it to one cup of coffee per day,” he added.

The source of caffeine — whether from coffee,
tea or sodas — didn't make a difference. But one thing to take into
consideration is that a cup of coffee can have varying amounts of
caffeine depending on how it is brewed, with some brands containing
more of the addictive chemical than others. A tall brewed coffee from
Starbucks, for instance, packs 270 mg of caffeine. A tall latte from
the chain, however, contains 75 mg.

In
the study, published in Monday’s issue of the American Journal of
Obstetrics and Gynecology, Li's team interviewed 1,063 women in the San
Francisco area who became pregnant between 1996 and 1998 about their
caffeine intake.  While 164 of the women drank 200 mg of caffeine or
more daily, 635 consumed some caffeine but less than 200 mg. The
remaining 264 women said they didn’t consume any caffeine.

Overall,
172 of the women suffered a miscarriage. The risk of a miscarriage was
more than double in women who consumed 200 mg or more of caffeine, with
25 percent suffering a miscarriage compared to just 12 percent of women
who didn't consume caffeine. The low-caffeine drinkers also appeared to
have an elevated risk of miscarriage, but this trend wasn't
statistically significant, meaning the researchers could not rule out
that it was merely due to chance.

Li said the 200 mg limit can be considered a
cutoff point where the miscarriage risk starts to emerge because the
median consumption of the high caffeine intake group was 301 mg per
day. This means half of these women were drinking less than 301 mg
daily, so heavy drinkers were probably not skewing the results.

To
determine the impact of morning sickness on the results, Li's team
looked separately at women who experienced nausea and vomiting and
those who did not. The miscarriage risk remained in both groups as long
as their daily caffeine intake rose above 200 mg. In addition, the
researchers looked at women who reduced their caffeine consumption
during their pregnancy and those that didn’t and found that the
miscarriage risk still remained in those consuming 200 mg or more of
caffeine per day.The increased risk remained even after
adjusting for other factors that could up the chances of a miscarriage,
such as age, previous miscarriage, smoking and alcohol consumption.

Although
it's not known for certain how caffeine might trigger a miscarriage,
one theory is that it restricts blood flow to the placenta, which could
have a detrimental effect on the developing fetus, Li said.

Overall
though, caffeine is not a major cause of miscarriage, which occurs in
up to 20 percent of known pregnancies. More than 60 percent of these
faulty pregnancies are due to chromosomal defects in the fetus that are
beyond the mother's control.

Doctors on the frontlines are divided on the
risks of caffeine. Dr. Tracy Flanagan, an obstetrician/gynecologist and
director of women's health for Northern California at Kaiser
Permanente, said that based on the study findings, she will be more
emphatic about advising her pregnant patients to cut back on coffee and
other caffeinated beverages.

Flanagan
said that along with other prenatal advice, such as taking folic acid
supplements, no alcohol and no smoking, she would add limiting caffeine
intake to no more than the amount in one cup of coffee per day or to
cut it out entirely.

But
Dr. Katharine O'Connell, a gynecologist at Columbia University, remains
unconvinced. She said the study would not be enough to change her
advice to patients and doubted it would overturn current
recommendations from the American College of Obstetricians and
Gynecologists that moderate caffeine intake during pregnancy is safe
(ACOG said it does not comment on individual studies).

“I would tell my patients that two cups of coffee per day should be fine,” O'Connell said.

She
noted however that the findings were intriguing because previous
studies that have linked caffeine to an increased risk of miscarriage
involved much higher amounts — the equivalent to several cups of coffee
per day. But the current study suggests the risks begin at a lower
amount, so this may warrant further investigation, she said.

It's too early to sound the alarm though,
according to O'Connell. Larger studies that confirm the miscarriage
risk would be necessary before these relatively low amounts of caffeine
are considered unhealthy, she said.

Without
a final word on the matter, moms-to-be are likely to hear conflicting
advice from their doctors and simply decide on their own whether lattes
are worth even the slightest chance of a risk.

Tammy
Plotkin-Oren, a coffee-lover and mother of three daughters in San
Francisco, said giving up java while pregnant is doable and she should
know. After her first attempt at pregnancy seven years ago ended in
miscarriage, Plotkin-Oren, 35, went cold turkey during subsequent
pregnancies.

Although
there's no way to know if her 3 to 4 cups of coffee habit per day
played a role in the miscarriage, she said she decided to eliminate her
intake during her next three pregnancies as part of her overall health
plan and each one resulted in a successful birth.

Plotkin-Oren
missed the social aspect of meeting friends for coffee and developed
headaches from caffeine withdrawal, but overall she found it easy to
kick the habit. “It wasn't that hard because I was committed to doing
everything I could to ensure a successful pregnancy,” she said.