It’s a daily ritual for many: a steaming hot cup of joe to kick off the morning. Coffee is one of the most popular beverages in the world. Americans drink more than 400 million cups a day, and women comprise roughly half of that consumption. But is coffee – and the caffeine in it – safe? It’s a question often asked, especially by women concerned about how caffeine affects their fertility.
Aaron K. Styer, MD, a fertility specialist and associate director of the Basic Science Research Program for the MGH Reproductive Endocrinology & Infertility Fellowship, says that, so far, there is no clear answer. Some studies have shown an association between caffeine and infertility, while others have not demonstrated any obvious adverse effects on a couple’s ability to conceive.
A study published this year in the British Journal of Pharmacology highlights a potential role of caffeine in reducing fertility and delaying conception in mice by slowing the transport of the egg through the fallopian tube. But a 2009 study by investigators at the Harvard School of Public Health followed 18,000 women for eight years and did not find that caffeine intake impaired ovulation to the point of decreasing fertility.
“The majority of previous studies analyzing the association between caffeine and fertility are retrospective and employed many different study designs,” Styer explains. “As such, there are inherent biases and study flaws that may contribute to a lack of consensus.”
The lack of consistent findings is frustrating to both practitioners and patients, leaving many wondering what to do. Styer advises pregnant women and women trying to become pregnant that they can consume caffeine in moderation until consensus is reached.
“For now, we can rely on expert opinion, which suggests that moderate caffeine consumption – one to two cups of coffee per day or its equivalent before or during pregnancy – has no apparent negative effects on fertility or pregnancy outcomes,” he says. “As with anything in life, everything in moderation – including caffeine.”