There is growing evidence suggesting that caffeine intake may be detrimental to pregnancy.

Introduction

Caffeine is a widely consumed stimulant, and up to 9 in 10 pregnant women report drinking coffee.1 International advisory panels have historically adopted a moderate approach to caffeine intake in pregnancy. For example, the European Food Safety Authority advises that ingesting up to 200mg of caffeine per day has not been shown to cause harm to the developing fetus,2 echoing advice from the American College of Obstetricians and Gynecologists (ACOG) and the UK National Health Service.1

However, there is growing evidence suggesting that caffeine intake may be detrimental to pregnancy. A recent systematic review of 26 studies showed that the risk of miscarriage increased by 32% in women who consumed caffeine (odds ratio [OR] 1.32, 95% confidence interval [CI] 1.24 to 1.40). Further, for every additional two cups of coffee per day, the risk of miscarriage rose by 8%.3

While the effect of caffeine intake on miscarriage has been less studied in men, prospective cohort data suggest that the risk of miscarriage may be up to 73% higher in men who drink ³2 cups of coffee per day in the preconception period in comparison to a daily intake of <2 cups (hazard ratio [HR] 1.73, 95% CI 1.10 to 2.72).4

The impact of caffeine intake on recurrent pregnancy loss (RPL) is less clear, although some studies have suggested an association between caffeine-induced high CYP1A2 activity and RPL.5 Additionally, retrospective data from 260 women suggested that in women with unexplained RPL the odds of miscarriage increased by 2.72 times for every 100 mg/day of caffeine intake (OR 2.724, 95% CI 2.715 to 2.733).6

Bullet point guidance

  • Pregnant women should be advised that existing evidence does not support safe levels of maternal or paternal caffeine consumption in couples with RPL.1
  • In women and men who choose to continue consuming caffeine in the pre-conception period and during pregnancy, clinicians should advise couples that the risk of miscarriage has been shown to be higher in those ingesting ³2 cups of moderate-strength coffee per day.4
  • Women with recurrent miscarriage should be advised to limit caffeine to less than 200 mg (2 cups) per day.7
  • The Tommy’s daily caffeine intake calculator is available on the following website: www.tommys.org/pregnancy-information/calculators-tools-resources/check-your-caffeine-intake-pregnancy

References

  1. James, J.E., Maternal caffeine consumption and pregnancy outcomes: a narrative review with implications for advice to mothers and mothers-to-be. BMJ Evidence-Based Medicine 2020: p. bmjebm-2020-111432.
  2. EFSA Panel on Dietetic Products, N. and Allergies, Scientific Opinion on the safety of caffeine. EFSA Journal 2015. 13(5): p. 4102.
  3. Li, J., et al., A meta-analysis of risk of pregnancy loss and caffeine and coffee consumption during pregnancy. International Journal of Gynecology & Obstetrics 2015. 130(2): p. 116-122.
  4. Buck Louis, G.M., et al., Lifestyle and pregnancy loss in a contemporary cohort of women recruited before conception: The LIFE Study. Fertility and Sterility 2016. 106(1): p. 180-188.
  5. Sata, F., et al., Caffeine intake, CYP1A2 polymorphism and the risk of recurrent pregnancy loss. Molecular Human Reproduction 2005. 11(5): p. 357-60.
  6. Stefanidou, E.M., et al., Maternal caffeine consumption and sine causa recurrent miscarriage. European Journal of Obstetrics & Gynecology and Reproductive Biology 2011. 158(2): p. 220-224.
  7. The ESHRE Guideline Group on RPL, Ruth Bender Atik, Ole Bjarne Christiansen, Janine Elson, Astrid Marie Kolte, Sheena Lewis, Saskia Middeldorp, Willianne Nelen, Braulio Peramo, Siobhan Quenby, Nathalie Vermeulen, Mariëtte Goddijn, ESHRE guideline: recurrent pregnancy loss, Human Reproduction Open, Volume 2018, Body Weight and Recurrent Pregnancy Loss Issue 2, 2018, hoy004, https://doi.org/10.1093/hropen/hoy004