Caffeine is a psychoactive drug because it changes brain function and results in alterations in perception, mood, or consciousness. Caffeine is a central nervous system stimulant found naturally in the seeds, nuts, and leaves of over 60 species of plants. This stimulant is commonly in coffee, tea, and energy drinks and is the most widely consumed drug in the world. Caffeine is one of the first things to be cautious about after seeing a positive pregnancy test. Trying to figure out how much caffeine is safe during pregnancy and breastfeeding can be challenging. This episode examines how you process caffeine and the recommendations and research on the safety of caffeine during pregnancy and breastfeeding.

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Caffeine is a psychoactive drug because it changes brain function and results in alterations in perception, mood, or consciousness. It is a central nervous system stimulant. It is found naturally in the seeds, nuts, and leaves of over 60 species of plants native to South America and East Asia. This stimulant is commonly in coffee, tea, and energy drinks and is the most widely consumed drug in the world.

How Your Body Processes Caffeine

When you consume caffeine, it passes through membranes in your body. This happens as soon as you take a sip of a drink with caffeine. It enters your bloodstream through the mouth, throat, and stomach lining. Within about 45 minutes, you absorb 99% of caffeine through this process. Caffeine is metabolized by your liver and broken down into three different metabolites. Eventually, you filter these metabolites through your kidneys and eliminate caffeine through your urine.

Effects of Caffeine

Caffeine works by blocking adenosine. Adenosine aids in the onset of sleep and passes through receptors in your brain throughout the day. When receptors pick up enough adenosine, it signals your body that you need to sleep. Caffeine works by blocking adenosine on receptors in your brain. This makes two things happen. First, your adrenal glands begin secreting adrenaline. Adrenaline causes an increase in your heart rate, body temperature, blood pressure, and blood sugar levels. Second, blocked adenosine leads to increased dopamine levels. Dopamine is associated with an elevation in mood. You can likely identify with this if you enjoy a coffee first thing in the morning. 

The Half-Life of Caffeine

An essential element of how you process caffeine is the half-life. The half-life of a drug is the amount of time it takes your body to remove half of the substance from your system. The time it takes your body to eliminate caffeine from your system will be different for everyone. The half-life of caffeine for adults ranges from 5-7 hours. On the short end of the spectrum, after 5 hours, your body processes 50% of the caffeine, and 50% remains. After another 5 hours, you process an additional 50%, leaving 25%. This means after 10 hours, roughly 25% of the caffeine you consume is still in your system. This time is even longer for someone who does not metabolize caffeine quickly.

Many factors can influence how long it takes your body to break down and process caffeine. This can include your genetic makeup, other medications you could be taking, your weight, your liver enzyme function, your age, and even the altitude where you live. 

How Pregnancy Affects Caffeine Metabolism

The way your body processes some drugs is altered when you are pregnant. Pregnancy increases the half-life of caffeine, so it remains in your system for a more extended period. As you get further along in your pregnancy, your body takes longer to process caffeine. It takes you longer to process caffeine in the second trimester than in the first and even longer in the third trimester. As your pregnancy progresses and your body takes longer to metabolize caffeine, you pass more of it to your baby. See this article to read more about the pharmacology of caffeine. 

How Caffeine Affects Your Baby 

During pregnancy, caffeine in your bloodstream crosses your placenta. Your baby can’t process caffeine as well as you can. Studies have examined caffeine intake in relation to fetal growth restriction, miscarriage, and low birth weight. In animal models, there is evidence that high caffeine consumption can disrupt implantation, fetal growth and development, pregnancy loss, low birth weight, and brain development.

Making an Informed Choice

Like so many things, you can always take the most conservative approach and abstain from caffeine during pregnancy. Rather than add this to the long list of things to avoid, let’s dive deeper so you have the information you need to decide whether you are comfortable consuming caffeine and what levels may be safe. We will start with caffeine content in foods and drinks, then discuss the recommendations for caffeine consumption and examine the evidence.

Sources of Caffeine

The most well-known source of caffeine is the coffee bean. An 8-ounce (237 milliliters) cup of coffee has between 95-200 milligrams of caffeine. The amount can differ depending on the bean type, the coffee’s strength, and the method of brewing it. Cold brew coffee tends to have less caffeine than regular coffee. Be careful because cold brew is often sold as a concentrate. You should check the caffeine content on the label and whether it recommends diluting it.

Tea leaves naturally contain caffeine. Some beverages containing caffeine, like sodas or energy drinks, use caffeine extracted from a plant and added in. Caffeine is also in cocoa beans, which are used to make chocolate. Generally, the darker the chocolate, the more caffeine it has.

Caffeine Content in Common Foods and Drinks

  • 5-hour energy shot 200-207 mg of caffeine 
  • Coffee (8 oz. or 237 ml) 95-200 mg 
  • Red Bull (8.4 oz. or 237 ml) 75-80 mg 
  • Diet coke (12 oz. or 355 ml) 23-47 mg 
  • Green tea (8 oz. or 237 ml) 24-45 mg 
  • Coca-Cola (12 oz. or 355 ml) 23-35 mg 
  • Black tea (8 oz. or 237 ml) 14-70 mg 
  • Dark chocolate (1 oz. or 28.4 g) 12 mg
  • Milk chocolate (1 oz. or 28.4 g) 6 mg

Recommendations for Caffeine Consumption

Caffeine is classified by the Food and Drug Administration as generally recognized as safe. A toxic dose would be over 10 grams per day for an adult. If one cup of coffee contains 95-200 mg of caffeine, it will take somewhere between 50–100 cups to reach a lethal dose. That is not to say you wouldn’t have adverse effects from high caffeine consumption, but it would be tough to get a deadly dose. It is generally recommended that healthy adults keep their caffeine consumption at 400 mg or less per day.

The recommendation during pregnancy is lower. The American College of Obstetricians and Gynecologists states 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 between caffeine to growth restriction remains undetermined. A final conclusion cannot be made at this time as to whether there is a correlation between high caffeine intake and miscarriage.

Canada sets the maximum daily intake at 300mg of caffeine per day for women trying to become pregnant or are pregnant or breastfeeding. The European Food Safety Authority states that pregnant or lactating women’s habitual caffeine consumption of up to 200 mg per day does not give rise to safety concerns for the fetus or breastfed infants.

200 mg is also the threshold most studies use to define moderate caffeine consumption. 200 mg is about one to two cups of coffee or about four cups of caffeinated tea. 

The Research on Caffeine and Pregnancy

There is extensive research on caffeine and pregnancy. Unfortunately, it is also very confusing, and many studies conflict with each other. 

Miscarriage Risk 

Over the last few decades, many concerns have been raised about exposure to caffeine and miscarriage. Many of the older studies that link caffeine to miscarriage had a small number of participants. Some of the more recent studies have attempted to use larger samples in the hopes we can get a clearer picture of whether there is a link between miscarriage and caffeine consumption.

One study with over 1,000 pregnant women found that high doses of caffeine intake during pregnancy increase the risk of miscarriage. Another study with over 2,400 participants ultimately found little indication of caffeine’s possible harmful effects on miscarriage risk within the range of coffee and caffeine consumption reported. This study measured caffeine consumption as none, under 200 mg per day, and over 200 mg per day. This is the opposite of what the first study found. Are you confused yet? Digging into more research on miscarriage and caffeine doesn’t clarify the answer.

Risk of Preterm Birth

Concerns have also been raised about preterm birth and caffeine consumption. As with miscarriage, many studies on caffeine and preterm birth have conflicting findings. A meta-analysis including 22 studies found no association between caffeine intake during pregnancy and the risk of preterm birth.

How Much Caffeine is Safe?

The bottom line is more research is needed to determine what amount of caffeine is 100% safe during pregnancy. Most studies use 200 mg per day as the cut-off as low or moderate consumption. This is in line with most recommendations by national health agencies around the world. 

The most conservative approach would be to cut out caffeine completely. A more recent paper highlights that a growing, robust body of evidence from both epidemiological and animal studies unveils harmful effects of maternal gestational caffeine exposure, even from doses previously considered safe. The authors do make the important note that caffeine sensitivity is highly variable from individual to individual.

If you do not want to cut out caffeine completely, you may choose to limit your consumption to 200 mg or less per day. You may be comfortable increasing that limit. It comes down to what you are comfortable with.

Caffeine and Gestational Diabetes

Since coffee may increase your blood glucose levels, you may need to be more cautious with caffeine if you have gestational diabetes. Gestational diabetes is a type of diabetes that affects 6-7% of pregnancies. There is evidence that caffeine impaired insulin sensitivity in women with gestational diabetes. Please ask your doctor or midwife if you have any questions about caffeine and gestational diabetes.

Additionally, you may want to skip a cup of coffee before a glucose challenge screening or a glucose tolerance test. The glucose challenge screening is a standard routine test in the United States between 24-28 weeks to evaluate how your body is processing sugar.

Caffeine and Sleep

Adenosine aids sleep onset, and if caffeine blocks adenosine receptors, you may feel awake. Once your body eventually processes the caffeine, all of the adenosine that accumulated in your system while you were under the effects of caffeine flood in. This “caffeine crash” can make you tired quickly. If you are consuming caffeine, whether or not you are pregnant, you want to consume it early enough in the day, so it does not affect your sleep.

Caffeine can make it more difficult to fall asleep and more difficult to stay asleep through the night. If you wake up tired, you are likely to start your day with more caffeine and start the cycle again. Given the half-life of caffeine, Dr. Matt Walker recommends avoiding caffeine within 12-14 hours before going to bed. Dr. Andrew Huberman recommends 8-10 hours. You can experiment with cutting off caffeine at different times to find what works best for you. See this episode for in-depth information on sleep.

Many new parents will experience a significant decrease in sleep with a newborn. As a result, many will use caffeine to feel more awake during the day. Caffeine can have a substantial impact on sleep. When you are decreasing the amount of sleep you get, you do not also want to reduce the quality of your sleep.

Breastfeeding and Caffeine Consumption

After you have your baby, you should be mindful of your caffeine consumption when you are breastfeeding because you can pass it through breast milk. The half-life of caffeine in a newborn has been estimated at as high as 100 hours. This decreases dramatically by six months. Some sources state the half-life of caffeine at six months is similar to adults. Other sources cite a much shorter half-life than adults at six months.

Although the half-life of caffeine for you is increased during pregnancy, it returns to normal levels within the first week postpartum. Since you absorb caffeine through membranes, it is present in your breast milk shortly after you drink it, and breast milk levels peak about one hour after consuming caffeine. This data can help you time your caffeine consumption with breastfeeding to limit the amount of caffeine you pass to your baby. The LactMed database is a fantastic resource for information about breastfeeding and drugs or medications. You can click here to read more about caffeine and breastfeeding.

ACOG states that drinking caffeine in moderate amounts (200 milligrams a day) most likely will not affect your baby. Newborns and preterm infants are more sensitive to caffeine’s effects. You may want to consume less caffeine in the first few days after your baby is born or if your infant is preterm. LactMed states that a maternal intake limit of 300 to 500 mg daily might be a safe intake level for most mothers. They also caution about the slow caffeine metabolism of preterm and newborn babies. LactMed also notes that coffee intake of more than 450 mL daily (about 15 ounces) may decrease breastmilk iron concentrations and result in mild iron deficiency anemia in some breastfed infants.

Infants exposed to high levels of caffeine in breast milk may be irritable, fussy, have trouble sleeping, or wake up frequently. If you think your caffeine consumption could be affecting your baby, cut back and pay attention to whether it changes your baby’s behavior.

Caffeine Alternatives

If you want to avoid caffeine, you already know the best thing for you to drink is water. If you drink soda, you know you need to watch caffeine, but there could also be some ingredients in there that are not ideal, like high amounts of sugar or artificial sweeteners. You may consider swapping beverages that typically have caffeine for caffeine-free or decaffeinated alternatives.

Decaf Coffee

There is no such thing as a caffeine-free coffee bean, and decaffeinated coffee will still have a trace amount of caffeine. The beans are put through a process to remove caffeine to make decaf coffee. The result is not caffeine free, and it will still contain between 2-12 mg for an 8 oz. (237 ml) cup. That small amount of caffeine seems very insignificant, and it is, assuming you are not drinking numerous cups of it. 

Decaf Tea

Black and green teas have caffeine since it is naturally in tea leaves. Many herbal teas are caffeine free since herbs, like peppermint, do not naturally contain caffeine. Tea can be a good alternative to coffee since it is much lower in caffeine. Not all teas are recommended during pregnancy. See this episode for more in-depth information on drinking tea during pregnancy.

Finding Solutions that Work For You

Caffeine is a stimulant, and it will not just stimulate you, but it will also stimulate your baby. Keeping your caffeine consumption in check is advised while you are pregnant. If you love your morning coffee, I know this seems like an impossible task now, but it is only a short-term change. Luckily for you, if you enjoy coffee or tea, the research isn’t clear that you have to avoid all caffeine. If you decide to enjoy a caffeinated beverage, just keep track of how much caffeine you consume.

Keep in mind that your body is working really hard right now. If you want to enjoy a cup of coffee or caffeinated tea and are comfortable doing that, you surely can. Rather than sip on a cup of caffeine and power through fatigue, take a nap or go to bed early. Your body will tell you when to slow down, but you must pay attention.

I love coffee, and when I was pregnant, I sometimes made half decaf half regular coffee so I could enjoy a second cup of coffee guilt-free. It’s about finding solutions that work for you and doing what you are comfortable with.

Talking to Your Doctor or Midwife

If you have any caffeine-related questions, please bring them up with your doctor or midwife. You should discuss amounts with your care provider to get their opinion on caffeine consumption if you consume caffeine.

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