Caffeine Consumption During Pregnancy
Kelsey McLaughlin, PhD
One of the most commonly searched questions online by pregnant women is 'can pregnant women drink coffee?'. This seems like a relatively simple question, but there are many online sources providing different types of information.
Let's see what the research shows!
Common sources of caffeine
When we think of caffeine, we tend to immediately think of coffee as being our main source of caffeine. However, caffeine is found in many other types of drinks and foods, including tea, cola & soft drinks, chocolate, energy drinks and some medications.
Health Canada has a helpful Fact Sheet that provides the amount of caffeine in common products.
Let's chat about how caffeine impacts the body
Caffeine is thought to be the most commonly consumed psychostimulant in the world, meaning it increases activity of the central nervous system.
Following the consumption of caffeine through beverages, foods or medication, caffeine in the gastrointestinal system is absorbed into the blood stream and travels throughout the body. Highest levels of caffeine in the blood stream are typically seen 30-60 minutes after consumption. The processes that break down and remove caffeine from the body can widely vary between people due to numerous factors, including differences in the enzymes that break down caffeine, food intake and smoking status.
Side fact - smokers metabolize (break down) caffeine twice as fast as non-smokers, due to the impact that cigarette ingredients have on liver enzymes.
Lower doses of caffeine (ie. amount consumed daily through diet) block receptors in the body called adenosine receptors. Adenosine receptors are involved with the release of neurotransmitters, inflammation and immune responses. When caffeine blocks adenosine receptors, this causes an increase in the release of neurotransmitters, such as dopamine, as well as other effects.
Side fact - there is some evidence to suggest that caffeine lowers the risk of neurodegenerative diseases, such as Alzheimer's. Scientists hypothesize that increases in neurotransmitters with adenosine blockage may lead to stimulation of the cognitive system and protection of the central nervous system. Keep your eye on that research in the future.
Caffeine can induce a wide-variety of effects, including the feelings of stimulation, cognitive skill improvement, anxiety, faster recovery from exercise, rapid beating of the heart and blood pressure changes.
Higher levels of caffeine can also impact calcium levels in muscle and inhibit certain enzymes; however, these effects are not expected with the typical dietary caffeine consumption.
How does caffeine impact pregnant women?
Caffeine is removed from the pregnant body more slowly than the non-pregnant body, due to changes in enzymes that break the molecule down. If caffeine is not being removed as quickly from the body, caffeine can begin to accumulate in the pregnant body and its effects are exerted for a longer period of time.
Caffeine in the mom's blood can easily cross through the placenta and enter the baby's blood stream, meaning that the baby is feeling the effects of caffeine also. The ability of the baby's body to remove caffeine from their system is much lower than the mom's body, since the enzymes needed to breakdown caffeine are not well developed.
Is it safe to consume caffeine while pregnant?
While there are numerous studies examining if caffeine impacts pregnancy outcomes, let's focus on the results of studies called meta-analyses. These types of articles combine the results of numerous studies in order to look at the overall effect and draw conclusions from there.
First, let's look at a meta-analysis published in 2015 that combined the results of 14 studies, with a total of 130,000 participants. The authors concluded that high caffeine consumption (>350 mg/day) during pregnancy was associated with increased risk of pregnancy loss, while low or moderate levels of caffeine consumption showed no association.
A Cochrane review published in 2015 also examined the effect of caffeine consumption by pregnant women on adverse pregnancy effects. Cochrane reviews are typically considered the gold standard of meta-analysis and their conclusions are widely respected. However, due to the lack of high-quality, randomized studies in this area, the authors concluded that there was insufficient evidence to support or oppose caffeine avoidance by pregnant women.
Another meta-analysis published in 2017 examined the overall impact of coffee consumption on health, in pregnant and non-pregnant individuals. 'High' consumption of coffee in pregnant women was found to increase the risk of low birth weight, pregnancy loss and preterm birth, when compared to pregnant women with 'low' coffee consumption. 'High' consumption of coffee in pregnant women was not associated with third trimester preterm birth, neural tube defects, or certain congenital malformations.
This article unfortunately could not provide a definition of what constituted 'high' or 'low' caffeine consumption, since it combined the results from multiple studies and consumption was measured in different ways. Some of the studies reported consumption as servings/day, cups/day, times a week etc.
Caffeine guidelines for pregnant women
Guidelines from the The Society of Obstetricians and Gynaecologists of Canada state that consumption of moderate amounts of caffeine (1-2 cups of coffee / day) is safe during pregnancy. Similarly, Health Canada recommends women who are pregnant, breastfeeding or planning to become pregnant should not consume more than 300 mg of caffeine in a day, which equals out to approximately 2 cups of coffee, 8 oz each.
The American College of Obstetricians and Gynecologists states that moderate daily caffeine consumption (less than 200 mg of caffeine / day) is considered safe by experts. While moderate levels of caffeine are not thought to contribute to the risk of miscarriage or preterm birth, the American college states that the exact relationship between caffeine and adverse pregnancy effects remain unclear and a conclusion cannot currently be made about the risks of high caffeine consumption during pregnancy.
Caffeine impacts the pregnant body differently than the non-pregnant body, and can cross the placenta to enter the baby's system. Recent research suggests that high levels of caffeine consumption during pregnancy may increase the risk of some adverse pregnancy outcomes. Canadian and American guidelines recommend reducing caffeine intake to moderate levels during pregnancy.
Every woman and every pregnancy is unique. Pregnant women should speak to their healthcare provider to ensure maternal and fetal safety. This article is meant to provide readers with current information and opinions. All medical and treatment decisions should be discussed with your healthcare provider.