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“Can I have caffeine while I’m pregnant?”: The History, the Evidence and Your FAQs

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This is a frequent question I get in at the first visit for a pregnancy:

“Is it okay to drink my [coffee, tea, soda…]. It has caffeine in it,”

The short answer is yes, there is data that supports that caffeine in low to moderate amounts is safe during all trimesters of pregnancy; but newer data suggest that there is more harm to caffeine than previous studies have found and that a safe number of daily milligrams is still unknown (James, 2021). In a review of 42 studies, 32 studies found negative effects when caffeine was consumed in pregnancy while 10 studies found no associations (James, 2021).

In light of this newer data, caffeine recommendations remain the same (200-300 milligrams a day is okay depending on the organization you’re looking at).

82% of pregnant women in America and 91% of pregnant women in France consume caffeine daily (James, 2021).

A Short History Lesson & The Current Evidence

Caffeine has been studied in pregnancy for decades. In rodents, caffeine causes small rate babies; in many of these studies, researchers give 70 milligrams per kilogram to the animals (James, 2021). In sheep, large caffeine doses reduced blood flow to the uterus but evidence has not supported this is the case in human uteruses (American College of Obstetricians & Gynecologists [ACOG], 2010).Cunningham et al., 2010). In the 1980s, pregnant women were told by the FDA (Food and Drug Administration) to avoid caffeine because they thought it was a teratogen to the pregnancy (teratogen means harmful) (James, 2021). Some evidence at that time showed that caffeine was not associated with any harmful risks and the recommendation was retracted (mainly because the soft drink companies went a little crazy trying to keep soda as an option for pregnant women to drink) (James, 2021; Cunningham et al., 2010).

Studies since then have found…

There is an increased risk of miscarriage:

  • Consuming more than 5 cups of coffee a day was associated with increased risk of miscarriage (Study: Klebanoff, 1999).
  • Consuming caffeine greater than or equal to 150 milligrams daily versus less than 150 milligrams daily was associated with a 32-36% increased risk of miscarriage (Studies: Fernandes et al., 1998; Li et al., 2015).
  • Each additional 100 milligrams of caffeine was associated with a 7-14% increased risk of miscarriage; each additional 150 milligrams was associated with a 19% risk of miscarriage (Studies: Chen et al., Greenwood et al., 2014) (Cunningham et al., 2010; James, 2021).
  • But…one study was a little different. Savitz et al. (2008) looked at 2,407 pregnancies and asked women how much caffeine they were consuming before they were pregnant, 4 weeks after their last menstrual period and before 16 weeks of pregnancy to see if caffeine levels increased the risk of miscarriage. The researchers looked at the amounts of caffeine reported by women (reported amounts were either none, less/equal to 200 milligrams or more than 200 milligrams) and they did NOT find an association between caffeine consumption and miscarriage (ACOG, 2010).

There is an increased risk of stillbirth…

  • Each additional 100 milligram of caffeine was associated with a 9-19% increased risk in stillbirth (Studies: Chen et al., Greenwood et al., 2014) (James, 2021).
  • Interestingly, some of the studies have looked to see if women that are slow metabolizers of caffeine are at increased risk of stillbirth; no single gene has been identified but a series set of three genes, when present, puts a woman at a twofold risk for stillbirth versus a woman without the gene set (James, 2021).

There is an increased risk for low birth weight or small for gestational age babies…

  • Consuming caffeine greater than or equal to 150 milligrams daily versus less than 150 milligrams daily was associated with a 52% increased risk of a small baby (Study: Fernandes et al., 1998).
  • Two meta-analyses* noted that mothers consuming high rates of caffeine had a 16-18% risk of a small for gestational age baby (*a meta-analysis is a higher/better level of evidence than an observational study).
  • Each additional 100 milligrams of caffeine was associated with a 7-13% increased risk of a small baby (Studies: Chen et al., Greenwood et al., 2014)
  • 2,600 women were compared; those drank more than 200 milligrams of caffeine versus only 100 milligrams were 1.4 times more likely to have fetal growth restriction during pregnancy (CARE study, 2008) (Cunningham et al., 2010; James, 2021).
  • Another study noted that the risk of fetal growth restriction increased based on the amount of caffeine consumed:
    • Consuming 100-199 milligrams daily = 1.2 times more likely
    • Consuming 200-299 milligrams daily = 1.5 times more likely
    • Consuming 300-399 milligrams daily = 1.4 times more likely (ACOG, 2010)
  • Lastly, in 2021, 2,055 women had their plasma levels of caffeine drawn and collected self-reports of caffeine use from the women. The study also analyzed genotypes to see who metabolized caffeine fast or slow.
    • Of 2,055 women, 35% consumed coffee while 41% consumed soda.
    • Women who reported drinking at least 50 milligrams and more than 50 milligrams had small reductions in the body size of the babies at birth.
    • ***This study is different for a couple reasons***
      • With consumption <200mg of caffeine, the researchers still found that babies were smaller at birth (even in the amounts of 50 milligrams – about ½ cup of coffee per day!).
      • The researchers looked at blood levels and reported caffeine use – this was not done in the other studies mentioned.
      • The researchers did not find any difference between caffeine use or baby measurements in the fast or slow metabolizers – this gives less strength to the argument that a woman’s metabolism plays a role in the amount of caffeine (Gleason, 2021).

There is NOT an increase in risk for preterm birth:

  • Caffeine consumption defined as “low”, “high”, “none” or per 100 milligrams were not associated with an increase in preterm birth (Studies: Santos et al., 1998; Maslova et al., 2010; Greenwood et al., 2014).
  • Consuming less than 500 milligrams daily is not associated with or preterm birth (Clausson, 2002; *These researchers did not find associations with caffeine and low birth weight infants or fetal growth restriction) (Cunningham et al., 2010).

There is an increase in risk for childhood acute leukemia:

  • Drinking 3 cups of coffee or more versus none daily was associated with a 67% increased risk of childhood leukemia (Study: Milne et al., 2011).
  • Drinking none versus low to high amounts of caffeine was associated with a 57-72% increased risk of childhood leukemia (Studies: Cheng et al., 2014; Thomopoulous et al., 2015) (James, 20201).

There is an increased risk for childhood overweight or obesity:

  • Mothers who consumed more than 150 milligrams of caffeine daily were 2.3 more times likely to have children that were obese at age 5 years old. (Data is based on 4 cohort studies and 1 case control study, all published since 2015) (James, 2021).

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What are the current recommendations?

That depends who you ask! Here are the current recommendations:

American Dietary AssociationLess than 300 milligrams daily; about 3 5-ounce cups of coffee*
American College of Obstetricians & GynecologistsUp to 200 milligrams daily; about 2 cups of moderate-strength coffee.   “Moderate caffeine consumption (less than 200 mg per day) does not appear to be a major contributing factor in miscarriage or preterm birth. The relationship of caffeine to IUGR remains undetermined. A final conclusion cannot be made at this time as to whether there is a correlation between high caffeine intake and miscarriage” (ACOG, 2010, p.1).  
Health CanadaLess than 300 milligrams daily.
European Food Safety AuthorityUp to 200 milligrams daily “does not give rise to safety concerns for fetus.”
UK National Health Service and Royal College of ObstetriciansLimit daily intake to 200 milligrams.
World Health Organization“For pregnant women with high daily caffeine intake (more than 300 mg per day), lowering daily caffeine intake during pregnancy is recommended to reduce the risk of pregnancy loss and low birth weight neonates” (World Health Organization, 2023, p.1)

Table citations: ACOG, 2010; Cunningham et al., 2010; James, 2021; World Health Organization, 2023.*Recommendation currently under review (James, 2021).

Okay great. Who’s following these recommendations?

We’re not really sure. A study in Finland tried to figure that out and found that 40% of pregnant women were consuming more than 200 milligrams daily (James, 2021).

That’s a lot of data. What else do I need to know?

The data could be a little skewed. Remember, when researchers are designing studies, they are trying to control certain things and it’s hard to control certain aspects of studies. Regarding caffeine, the type of caffeine is assumed to be coffee, but people get caffeine from all sorts of drinks and foods. Think of the differences between coffee across households. For example if you and your friend Jane both brew a cup of coffee at your house, who’s to say you guys have the same amount of caffeine in your coffee? Or your tea? The brand of coffee or tea and how it is prepared contribute to the amount of caffeine in the drink or food. As you see, the exact measurement of the milligrams gets dodgy really fast. This is an issue at vendors as well. In this example, you get a mild roast coffee at Starbucks that’s served black, while Susie gets a dark roast with a large splash of cream. Susie has less caffeine than you do, right? Maybe not depending how much caffeine her dark roast has!

Genes play a role here too. Talk to enough people and you’ll find some that are really sensitive to caffeine. How we metabolize caffeine is different and this is an individualized piece in caffeine consumption in pregnancy.

And marketing is always an issue – remember in the beginning how I mentioned soda companies went berserk when the FDA wanted to say caffeine was unsafe? Well, a lot these studies don’t study soda intake. There’s a reason for that (History lessons are important for this reason!). If someone marketed “soda consumption is associated with negative effects for your baby” – well, it’s not going to go over well with the primary grocery shoppers of America – women.

Lastly, recall bias is a factor in studies. When I ask you about how much caffeine you drink, your answer is biased because we’re not great at recalling things as humans. But when a randomized controlled trial is executed – the researchers are measuring everything you’re doing and recall bias isn’t a factor.

Whew, okay, onto the fun stuff. The FAQs I get asked about caffeine.

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FAQs

What is caffeine?

Caffeine is a drug that is a stimulant, often put in drinks, foods and medications, or occurring naturally, like in coffee. You can take a deep dive on caffeine at Harvard’s School of Public Health here.

What happens to the caffeine in my body during pregnancy?

Caffeine is absorbed into the blood stream and crosses the placenta at the same level you consume it (i.e. the baby gets the same amount of caffeine that you do mama). How do researchers know this? There is caffeine in the baby’s hair that is consistent with the levels of how much caffeine a mother consumed in the third trimester of her pregnancy (James, 2021).

Is the baby able to digest or process the caffeine?

Caffeine is not digested well by the baby because the baby’s liver cells (P450) remain immature but some excrement of the caffeine does occur. The rest of the caffeine absorbs into the baby’s tissues. 80% of caffeine is passed through the baby’s kidneys and out of the body as urine – but this varies from trimester to trimester. In the first trimester, the rate of clearance is unchanged (80%); but in the second and third trimesters, the rate drops to half (50%) and then to a third of the rate (20-30%). This just means the baby’s holding the caffeine in their system a lot longer than in the beginning of pregnancy (James, 2021).

What does caffeine do to my body?

  • Constricts your brain and heart vessels (increases your blood pressure and heart rate).
  • Increase rate of kidney filtration (makes you pee more).
  • Opens the airways (bronchodilator).
  • Increases acid secretion to your bowels (can make you poop more) (James, 2021).

What is a safe amount of caffeine in pregnancy?

Probably 50-200 milligrams of caffeine each day with the biggest risks noted above 300 milligrams daily. Although some data from 2021 suggest that even small doses of 50 milligrams have effects.

Can I use caffeine at any time during pregnancy?

Yes. It’s not uncommon for many women to abstain from coffee in the first trimester because of the smell or taste; usually this goes away in the second trimester and coffee consumption is resumed as tolerated.

It’s also normal for caffeine tolerance to become lower in the third trimester because the half-life of caffeine increases from about 5 hours in the first trimester for women to 18 hours at 38 weeks of pregnancy (James, 2021).

What sources of caffeine are okay during pregnancy?

  • Coffee (8 ounces, 137 milligrams; instant coffee, 76 milligrams)
  • Teas (hot or iced, about 48 milligrams per 8 ounces)
  • Soft drink or soda (37 milligrams per 12 ounces)
  • Hot cocoa (8-12 milligrams per 12 ounces)
  • Chocolate milk (5-8 milligrams per 8 ounces)
  • Candy: milk or dark chocolate, chocolate syrups (3-30 milligrams depending on serving/food)
  • Coffee ice cream or frozen yogurt (2 milligrams per ½ cup) (American College of Obstetricians & Gynecologists, 2010)

What sources of caffeine are not recommended?

  • Energy drinks that have caffeine are not recommend in pregnancy. In general, energy drinks should not be consumed during pregnancy.

Should I reduce my caffeine intake to a lower level?

This decision is up to you; look at the amount of caffeine you ingest on a daily basis and compare that to the data that we have from research. Think about what purpose caffeine has for you and how a cup of coffee or tea serves you. What would happen if you stopped drinking caffeine products?

Should I drink decaffeinated coffee instead?

That’s up to you. When researchers compared drinking 3 cups of decaffeinated or caffeinated coffee, they found no difference in birth weight or gestational age among 1200 women studied (Bech, 2007) (Cunningham et al., 2010).

What guidelines exist for caffeine use in pregnancy?

Is caffeine use related to infertility?

We don’t think so. A systematic review from 2020 found that low, moderate and high doses of caffeine do not appear to increase the risk of infertility. Read the study here.

What other resources offer information about caffeine?

Whew. Officially, you’re all experts now. But really, you just have the data and information your need to make the best decision for you and your baby.

Talk with your provider about your caffeine use and risk factors and make a plan for your pregnancy.

Who’s ready for a cup o’ joe? ☕️

References

American College of Obstetricians & Gynecologists. (2010). Moderate caffeine consumption during pregnancy. Committee opinion. Number 462. https://www.acog.org/clinical/clinical-guidance/committee-opinion/articles/2010/08/moderate-caffeine-consumption-during-pregnancy?utm_source=redirect&utm_medium=web&utm_campaign=otn

Cunningham, F.G., Leveno, K., Bloom, S., Hauth, J., Rouse, D, & Spong, C. (2010). Williams obstetrics (23rd ed.). McGraw-Hill.

Gleason, J.L., Tekola-Ayele, F., Sundaram, R. (2021). Association between maternal caffeine consumption and metabolism and neonatal anthropometry: A secondary analysis of the NICHD fetal growth studies–singletons. JAMA Netw Open, 4(3):e213238. doi: 10.1001/jamanetworkopen.2021.3238

James, J. (2021). Maternal caffeine consumption and pregnancy outcomes: A narrative review with implications for advice to mothers and mothers-to-be. BMJ Evidence-Based Medicine, 26(3). doi: 10.1136/bmjebm-2020-111432

World Health Organization. (2023). Restricting caffeine intake during pregnancy. https://www.who.int/tools/elena/interventions/caffeine-pregnancy#:~:text=WHO%20Recommendations,and%20low%20birth%20weight%20neonates

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