Women today are deluged with information about what is and is not good to do during pregnancy -- or while they are trying to get pregnant. They are careful to eat proper nutrients. They give up smoking. They exercise and cut out alcohol.
For many women, a good cup of coffee in the morning is probably the only treat they do allow themselves.
But new studies have claimed that pregnant women who consume as little as 48 milligrams of caffeine a day may have a greater risk of miscarriage than those who consume no caffeine. That's less than half a cup a day.
Since that first study, a great deal of conflicting information has been published. Most seems to indicate that, indeed, moderate intake is OK. But what is moderate, and how can a woman tell? I asked Dr. Frank Witter, an associate professor of obstetrics and gynecology in the Division of Maternal/Fetal Medicine at the Johns Hopkins School of Medicine, to talk about this issue.
Q: What is considered a modest amount of caffeine?
A: One to two cups of coffee a day. With this amount of caffeine consumption, there is no measurable risk to a fetus, and there is no risk of
Q: What about women who are trying to conceive?
A: The major documentable effect of high caffeine consumption does concern women who are trying to become pregnant. In women who consume nine cups of coffee or more, we see a decrease in the ability to conceive. But at this level of intake, we are talking about the person who drinks coffee all day, as a habit. But it's important to know that the effect is completely reversible and that reversal begins as soon as women reduce their caffeine intake.
Q: What about those studies that link caffeine to low birth weight?
A: One of the problems with these studies is that often coffee drinkers have other contributing factors. They may be smokers or they may consume alcohol during pregnancy, both of which are associated with low birth weight.
Studies so far have not consistently considered these factors in analyzing their results. We cannot blame low birth weight on caffeine consumption alone, if the effects of other variables have not been included.
Q: From what products do women get caffeine?
A: There are many sources of caffeine we tend to forget. For instance, caffeine is found not only in coffee, but also in tea and in cola drinks. Chocolate is a known source of caffeine, as is chocolate milk. In addition, at least 1,000 over-the-counter drugs contain caffeine. These include diet pills, cold medications, painkillers and alertness aids. Even decaffeinated coffee has some caffeine.
Q: What does caffeine do that is so bad?
A: No one really knows exactly what caffeine does or how "bad" it is. Caffeine is a drug that stimulates the central nervous system. It can cause nervousness, irritability, anxiety, insomnia and irregular heart rhythms.
Caffeine affects people in different ways. The important thing to remember is moderation. For pregnant women, this means consuming no more than 300 milligrams a day. That's about three cups of coffee, more than enough to get you going and let you have at least one break in your careful regimen of staying healthy for your child.
Dr. Matanoski is a physician and epidemiologist at the Johns Hopkins School of Hygiene and Public Health. She is a founding director of its Institute for Women's Health Research and Policy.