Who doesn’t love coffee, tea or other caffeinated beverages? They’re an inseparable part of our everyday routine, and their tempting flavours often make them hard to resist. Many women around the world continue to enjoy caffeinated beverages whether they are trying to conceive or are already pregnant — Finland, for example, has one of the highest coffee consumption rates in the world, at around 12.0 kg per person per year.1
But does this really matter? There have been a number of opinions on the topic. However, given the growing public health concern around subfecundity and infertility, it’s worth taking a closer look.
On average, a cup of coffee contains about 100mg of caffeine, though this varies depending on the type of coffee bean used and how it is prepared. According to Food Standards Australia and New Zealand,2 typical caffeine content includes:
| Food / Drink | Caffeine Content |
|---|---|
| Espresso | 145 mg / 50 mL cup |
| Formulated caffeinated (‘energy’) drinks | 80 mg / 250 mL can |
| Instant coffee (1 teaspoon/cup) | 80 mg / 250 mL cup |
| Black tea | 50 mg / 250 mL cup |
| Coca-Cola | 48.75 mg / 375 mL can |
| Milk chocolate | 10 mg / 50 g bar |
In the body, caffeine affects a range of physiological processes: it alters blood levels of catecholamines and increases intracellular cyclic AMP. It is believed to affect the reproductive system through changes in endogenous hormone levels that in turn influence ovarian function.1 A study conducted from 2005–2007 in the United States found numerous associations between caffeine intake and reproductive hormone levels.3 One proposed reason is that caffeine and the reproductive hormone estradiol share a common metabolic pathway — both are metabolised by the hepatic enzyme CYP1A — so this pathway may allow caffeine to interfere with estradiol levels. Compounds such as isoflavonoids, found in significant amounts in coffee, may also have an increased affinity for oestrogen receptors, and resulting changes in hormone levels could affect the menstrual cycle.
That said, findings have been mixed: a study published in the Journal of Caffeine Research in 2011 found no effect of caffeine intake on outcomes for men and women receiving fertility treatment,4 while other studies have found an association between caffeine intake and hCG and oestrogen levels.5 Considering this, there remains a need for further research into caffeine consumption and natural fertility — but it’s a good reminder to discuss dietary habits, including caffeine intake, with your practitioner if fertility is a current focus.
References
- Lyngsø, J., Ramlau-Hansen, C. H., Bay, B., Ingerslev, H. J., Hulman, A., & Kesmodel, U. S. (2017). Association between coffee or caffeine consumption and fecundity and fertility: a systematic review and dose-response meta-analysis. Clinical Epidemiology, 9, 699–719. doi:10.2147/CLEP.S146496
- Food Standards Australia and New Zealand (2019). Caffeine. Retrieved from foodstandards.gov.au
- Schliep, K. C., Schisterman, E. F., Mumford, S. L., Pollack, A. Z., Zhang, C., Ye, A., … & Wactawski-Wende, J. (2012). Caffeinated beverage intake and reproductive hormones among premenopausal women in the BioCycle Study. The American Journal of Clinical Nutrition, 95(2), 488–497. doi:10.3945/ajcn.111.021287
- Choi, J. H., Ryan, L. M., Cramer, D. W., Hornstein, M. D., & Missmer, S. A. (2011). Effects of caffeine consumption by women and men on the outcome of in vitro fertilization. Journal of Caffeine Research, 1(1), 29–34.
- Lawson, C. C., LeMasters, G. K., Levin, L. S., & Liu, J. H. (2002). Pregnancy hormone metabolite patterns, pregnancy symptoms, and coffee consumption. American Journal of Epidemiology, 156(5), 428–437.
