But a new position statement issued by the American College of Obstetricians and Gynecologists (ACOG) should put some of their fears to rest. The group states that moderate caffeine intake -- less than 200 milligrams a day -- won't increase their risk of miscarriage or preterm birth.
The same cannot be said for higher amounts of caffeine, the group states in the August issue of Obstetrics & Gynecology.
"For years, women have been getting mixed messages about whether or not they should have any caffeine during pregnancy," says William H. Barth Jr., MD, chair of ACOG's committee on obstetric practice, in a news release. "After a review of the scientific evidence to date, daily moderate caffeine consumption doesn't appear to have any major impact in causing miscarriage or preterm birth."
Variations in Caffeine Content
In general, 200 milligrams of caffeine is equal to one 12-ounce cup of coffee, but coffee drinkers should be aware that there can be tremendous discrepancies in different brews. For example, a grande 16-ounce Starbucks brewed coffee has 320 milligrams of caffeine.
Eight ounces of caffeinated tea and most 12-ounce soft drinks have less than 50 milligrams of caffeine; 1.55-ounce chocolate bars have less than 35 milligrams, according to information cited in the new report.
The new opinion statement is based on a literature review of recent studies looking at the effects of caffeine on pregnancy. The authors also looked at how caffeine affects risk of intrauterine growth restriction (IUGR) during pregnancy. While there is no definitive evidence that caffeine increases risk of IUGR, more study is needed to better understand this relationship, the new paper states.
Sami David, MD, a New York City-based reproductive endocrinologist and pregnancy loss expert, tells his patients to play it safe when it comes to caffeinated beverages during pregnancy.
"One cup of coffee a day, which is about 8 ounces and has around 100 milligrams of caffeine, or two cups of black or green tea per day is OK," says David.