This is a topic that doesn’t go away. Over the years we have heard conflicting recommendations on the risks of caffeine during pregnancy. It increases the risk of miscarriage. It doesn’t. It increases the risk of preterm labor and fetal growth restriction. It doesn’t. According to a 2010 review by the Cochrane Library, “sufficient evidence is not available from randomized controlled trials to support any benefits from avoiding caffeine during pregnancy.” So what do we really know about the risks of caffeine during pregnancy?
The following four studies are cited in the 2010 edition of Williams Obstetrics:
1. In a 1999 case-control study, researchers compared levels of a substance which is a biological marker for caffeine consumption in 487 women who experienced spontaneous miscarriages, with levels in 2087 controls. Only extremely high levels, equivalent to more than 5 cups of coffee per day, were associated with miscarriage.
2. A 2002 prospective cohort study of almost 1000 women found no association of moderate caffeine intake of 500 mg. or less daily with low birthweight, fetal-growth restriction, or preterm delivery.
3. In a 2007 randomized, double blind trial of 1207 pregnant women recruited before 20 weeks gestation who drank at least 3 cups of coffee per day, researchers assigned women to either caffeinated instant coffee (n=568) or decaffeinated instant coffee (n=629) groups. The researchers concluded that a moderate reduction in caffeine intake in the second half of pregnancy has no effect on birth weight or length of gestation.
4. In a 2008 prospective longitudinal observational study of 2635 low risk women recruited between 8-12 weeks of pregnancy, investigators scientifically measured caffeine levels throughout pregnancy. They found that caffeine consumption during pregnancy was associated with an increased risk of fetal growth restriction and that this association continued throughout pregnancy. The authors concluded that, “sensible advice would be to reduce caffeine intake before conception and throughout pregnancy.”
And finally in a brand new study published in June, 2010 (not cited in Williams):
Researchers in the Netherlands measured the associations of maternal caffeine intake with fetal growth characteristics in each trimester of pregnancy and the risks of adverse birth outcomes in 7346 pregnant women participating in population-based prospective cohort study from early pregnancy onward. Caffeine intake was measured in each trimester by questionnaires and fetal growth characteristics were measured by ultrasound. Information about birth outcomes was obtained from hospital records. The investigators found that caffeine intake of equal to or more than 6 cups (540 mg caffeine) of coffee is associated with impaired fetal length growth.
So what should the childbirth educator recommend? It would be safe to go along with the American Dietetic Association recommendation that pregnant women keep their intake of caffeine to less than 300 mg per day. The tricky thing is knowing how much caffeine is in a particular beverage. For a quick and effective childbirth class activity, take to class a collection of examples of caffeine-containing beverages (soda can, several sizes of cups from Starbucks®, tea bag, etc.) Make some cards with the number of mg. of caffeine in each beverage. Ask class members to match the card with the appropriate mg. of caffeine to each example that you have.
I think it’s time for my second cup of coffee!