Should you consume caffeine while pregnant?

If you are pregnant, a health professional has likely advised you to limit your intake of caffeine while pregnant. This is because experts have linked high levels of caffeine consumption to complications, such as low birth weight and miscarriage.¹ However, that doesn’t mean that a small amount of caffeine will cause harm. So, what level of caffeine is considered safe, and how does that equate to real-life measures?

Current guidelines on caffeine while pregnant

The American College of Obstetricians and Gynecologists (ACOG) states that it is safe to consume 200 milligrams or less caffeine in a day. This is also the guidance from other international organizations such as the National Health Service (NHS), World Health Organization (WHO), and the Royal College of Midwives (RCM).  

It is advised that going above the 200 milligrams recommended limit might slightly increase the risk of miscarriage or pre-term birth. However, existing evidence is inconclusive. Most studies have been limited to small sample sizes.^{1 2}The RCM states that research does show a link between caffeine consumption greater than 300mg a day and lower birth weight. However, there is no evidence to link low maternal caffeine consumption in pregnancy (less than 200mg) to adverse pregnancy outcomes.³ 

What counts as caffeine intake?

It can be confusing trying to work out what 200 milligrams of caffeine looks like in your everyday diet? So here are a few quick caffeine comparisons. 

• 1 cup instant coffee = 100mg
• 8 oz (1 mug) of brewed drip coffee = 137 mg
• 1 can (12 oz) Coca Cola = 34mg
• 1 can (12 oz) Diet Coca Cola = 46mg
• 1 can (8oz) of Red Bull = 80mg 
• 8 oz (1 mug) of tea = 75mg
• One 45g bar Dairy Milk chocolate = 9mg
• 1 cup decaf coffee = 5-30mg

Beware that some energy drink brands can contain a lot more caffeine – some up to 400mg! That is double the recommended daily intake in one can alone. Caffeinated drinks like energy drinks and soda are also extremely high in sugar. Therefore, it is better to limit these where possible as part of a healthy diet.¹

Recent research studies

In August 2010, a research paper published in the BMJ Evidence-Based Medicine stated that women should avoid all caffeine while pregnant, and that professional bodies should revise the guidance of 200mg caffeine per day. However, in response to this paper, the RCM conducted a review of the available scientific evidence. They concluded that the international guidance that women should avoid high caffeine consumption of over 200mg a day should continue. This was supported by a statement from the RCOG, who stated that “moderate caffeine consumption of less than 200 mg per day does not appear to be a major contributing factor in miscarriage or pre-term birth.”^{2 3}

A more recent research study published in February 2021 reports that caffeine consumed during pregnancy can lead to behavioral problems later in life. The study examined 9,000 brain scans of children aged 9-10 years old whose mothers consumed caffeine during pregnancy. Scientists identified changes in brain pathways that could lead to behavioral problems later in childhood, such as attention difficulties and hyperactivity.^{4 5}

However, at what point in pregnancy caffeine leads to these changes is not fully understood, and the scientists found no changes in children’s intelligence or thinking ability. This retrospective study relied on mothers to remember how much caffeine they consumed during pregnancy many years ago. Further research is needed to investigate the link between caffeine in pregnancy and brain development, and the guidelines still remain the same.^{4 5}

Why is drinking caffeine in pregnancy different?

When pregnant, it can take 1.5–3.5 times longer to remove caffeine from your body, as pregnant women metabolize caffeine at a much slower rate. It is also known that caffeine crosses the placenta and enters the baby’s bloodstream. The baby’s metabolism is still developing and cannot fully metabolize caffeine.⁶

Caffeine also increases the pregnant mother’s catecholamine levels (which are the adrenaline hormones released when experiencing stress).²In addition, the American Pregnancy Association (APA) advises that caffeine increases your blood pressure and heart rate due to its stimulant qualities, both of which you do not want to raise during pregnancy.⁷These are just a few of the reasons why it is advised to be cautious when consuming caffeine in pregnancy. 

The bottom line

According to international professional bodies, moderate caffeine consumption of less than 200 mg per day is considered safe during pregnancy. However, it is easy to go over the limit, and high levels of caffeine intake have been linked with some pregnancy complications. If you are concerned about how much caffeine you are drinking, unsure about how to cut down, or want to know alternatives, speak to your doctor or midwife for advice. They can help you adjust your caffeine intake to a level considered safe for you and your baby. 

References:

1. Check your caffeine intake in pregnancy. Tommys.org. https://www.tommys.org/pregnancy-information/calculators-tools-resources/check-your-caffeine-intake-pregnancy#:~:text=The%20current%20NHS%20guidelines%20recommend,increases%20the%20more%20you%20have. Published 2021. Accessed February 19, 2021.

2. Moderate Caffeine Consumption During Pregnancy. Acog.org. https://www.acog.org/clinical/clinical-guidance/committee-opinion/articles/2010/08/moderate-caffeine-consumption-during-pregnancy. Published 2021. Accessed February 19, 2021.

3. Caffeine In Pregnancy. RCM Expert Clinical Advisory Group (ECAG) briefing; 2020. https://www.rcm.org.uk/media/4395/caffeine-in-pregnancy-oct2020-003.pdf. Accessed February 19, 2021.

4. Brain changed by caffeine in utero, study finds. EurekAlert!. https://www.eurekalert.org/pub_releases/2021-02/uorm-bcb020821.php. Published 2021. Accessed February 19, 2021.

5. Christensen Z, Freedman E, Foxe J. Caffeine exposure in utero is associated with structural brain alterations and deleterious neurocognitive outcomes in 9–10 year old children. Neuropharmacology. 2021;186:108479. doi:10.1016/j.neuropharm.2021.108479

6. Rhee J, Kim R, Kim Y et al. Maternal Caffeine Consumption during Pregnancy and Risk of Low Birth Weight: A Dose-Response Meta-Analysis of Observational Studies. PLoS One. 2015;10(7):e0132334. doi:10.1371/journal.pone.0132334

7. Caffeine Intake During Pregnancy | American Pregnancy Association. American Pregnancy Association. https://americanpregnancy.org/healthy-pregnancy/pregnancy-health-wellness/caffeine-intake-during-pregnancy-946/. Published 2021. Accessed February 19, 2021.

Image by Cindy Parks from Pixabay