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Caffeine is considered a psychoactive drug, meaning that it changes brain function and results in alterations in perception, mood, or consciousness. It is the most widely consumed drug in the world and is most commonly found in coffee, tea, and chocolate. Caffeine is one of the very first things to be cautious with once you see that positive pregnancy test.  Trying to figure out whether you can have caffeine when you are pregnant can be confusing. Understanding how caffeine effects your body, and how it is processed will be help you to determine whether you are comfortable enjoying some caffeine when you are expecting.  Some common questions are: Can you consume caffeine during your pregnancy? Does caffeine affect your baby?  How much caffeine is okay when you are pregnant? This episode answers these questions, dives into all of the details on caffeine and pregnancy, and talks about what the research says about caffeine consumption when you are pregnant.

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What is Caffeine?

You know that caffeine is a stimulant in coffee, tea, and energy drinks. But what exactly is caffeine?  Understanding what caffeine is and how your body processes it will help put all of the research into context. Caffeine is found naturally in the seeds, nuts, and leaves of over 60 species of plants native to South America and East Asia.  It is a central nervous system stimulant.  Caffeine is considered a psychoactive drug. This is because it changes brain function and results in alterations in perception, mood, or consciousness. Caffeine is the most widely consumed drug in the world.  

How Caffeine Affects Your Body

Throughout the day adenosine, which aids in the onset of sleep, is passing through receptors in your brain. When enough adenosine is picked up by receptors it signals your body that you need to sleep. Caffeine works by blocking adenosine on receptors in your brain. When adenosine is blocked this makes two additional 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.

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 blood stream through the lining of your mouth, throat, and stomach. Within about 45 minutes 99% of the caffeine is absorbed through this process. Caffeine is metabolized by your liver and broken down into three different metabolites. Eventually these metabolites are filtered through your kidneys and are eliminated through your urine. 

The Half Life of Caffeine

The half-life of a drug is the amount of time it takes your body to naturally remove half of the substance from your system. The time it takes your body to fully eliminate caffeine from your system is going to be different for everyone. I found quite a range on the half-life of caffeine for adults ranges anywhere from from 3-7 hours. If you are on the short end of that spectrum, after 3 hours your body has processed 50% of the caffeine out of your system and 50% remains. After another 3 hours 50% of that is processed out, leaving 25%. 3 hours later half of that is gone, leaving 12.5%. This means after 9 hours, roughly 12% of the caffeine you consumed 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

A huge factor that increases the half-life of caffeine, meaning that it remains in your system for a longer period, is pregnancy. When you are pregnant there are so many physiological changes going on in your body. The way your body processes some drugs, like caffeine, is altered from the way it would process caffeine if you were not pregnant. 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 that the first, and even longer in the third trimester. As your pregnancy progresses and your body is taking longer to metabolize caffeine, that means more of it is being passed on to your baby. In addition, the half-life of caffeine in a newborn has been estimated at as high as 80 hours. Since we are really taking a look at how caffeine affects you and your baby during your pregnancy, the time it takes you and your baby to process caffeine, is a big deal.

Check out this article if you want to go deep and read more about the pharmacology of caffeine.

How Caffeine Affects Your Baby

During pregnancy, caffeine in your blood stream crosses your placenta. Your baby doesn’t have the capability to process caffeine like you do and it will be in their system much longer. I mentioned an estimate of 80 hours. After you have your baby you will also want to be mindful of your caffeine consumption when you are breastfeeding, because it can also be passed to your little one through breastmilk.

Sources of Caffeine

The most well-known source of caffeine is the coffee bean. An 8 ounce, or 237 milliliter, cup of coffee has somewhere between 95-200 milligrams of caffeine. There is a range because this can differ depending on the type of the bean, the strength of the coffee, and the method of brewing it. Cold brew coffee tends to have less caffeine than regular coffee, but beware of buying cold brew which is often sold as a concentrate. You want to check the caffeine content on the label and whether it recommends diluting it. The leaves that are used to make tea also naturally contain caffeine. Some beverages containing caffeine, like sodas or energy drinks use caffeine that has been extracted by a plant and added in. Caffeine is also found in cocoa beans, which means that chocolate has some caffeine.  Generally the darker the chocolate the more caffeine it has. 

Common Drinks and Amounts of Caffeine

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

Black tea (8 oz. or 237 ml) – 14-70 mg

Coca-Cola (12 oz. or 355 ml) – 23-35 mg

Diet coke  (12 oz. or 355 ml) – 23-47 mg

Green tea (8 oz. or 237 ml) – 24-45 mg

Milk chocolate (1 oz. or 28.4 g) – 6 mg

Dark chocolate (1 oz. or 28.4 g) – 12 mg

Recommendations for Caffeine Consumption

It is generally it is recommended that healthy adults keep their caffeine consumption at 400 mg or less per day. Conservatively 200 mg for pregnant or breastfeeding mothers, or women who are planning to become pregnant. I have seen some higher estimates but just to be on the safe side, we will use 200 mg. This is also the threshold most studies use. 200 mg is one to two cups of coffee or about four cups of tea in one day.

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, remember the recommended consumption is around 400 mg for a healthy adult. If one cup of coffee contains 95-200 mg of caffeine, it would take somewhere between 50–100 cups of coffee to actually reach a lethal dose. That is not to say you wouldn’t have negative effects from high caffeine consumption, but it would be tough to get a lethal dose. 

The Research on Caffeine and Pregnancy

The research on caffeine and pregnancy is pretty extensive, unfortunately it is also very confusing and a lot of studies conflict each other.

Miscarriage Risk

Over the last few decades there have been a lot of concerns 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.

A study with over 2,400 participants ultimately found that there is little indication of possible harmful effects of caffeine 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. Another study found that high doses of caffeine intake during pregnancy increase the risk of miscarriage. This is the opposite of what the first study found. Are you confused yet? Digging into more research on miscarriage and caffeine doesn’t really make the answer any more clear. Until we have more sufficient evidence most guidelines recommend that it is best to minimize caffeine consumption and go with a more conservative approach. 

Risk of Preterm Birth

In the past concerns have also been raised about preterm birth and caffeine consumption. In a meta-analysis that looked at 22 studies found no important association between caffeine intake during pregnancy and the risk of preterm birth for cohort and case-control studies. This is consistent with ACOG’s opinion which is that there does not seem to be evidence showing caffeine consumption is linked to preterm birth. 

The Recommendation From the American College of Obstetricians and Gynecologists 

The official opinion of the American Congress of Obstetricians and Gynecologists is that moderate caffeine consumption, which they define as 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 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.

How Much Caffeine is Safe?

The bottom line is more research is needed to determine what amount of caffeine is 100% safe during pregnancy. The majority of the studies are looking at 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.

Canada recommends that women of reproductive age consume no more than 300mg of caffeine per day.  The Food Standards Agency in the U.K. states that pregnant and breastfeeding women are advised not to have more than 200mg of caffeine over the course of a day, which is roughly two mugs of instant coffee or one mug of filter coffee. Overall the most conservative approach would be to cut out caffeine, after that, would be to limit your consumption to the equivalent of one cup of coffee per day.

Decaf Coffee and Tea

I love coffee and when I was pregnant I would sometimes make half decaf half regular coffee so I could enjoy a second cup of coffee. It’s about finding solutions that work for you and doing whatever you are comfortable with. One thing you should know is that if you order a decaffeinated coffee, there is still going to be a trace amount of caffeine. There is no such thing as a caffeine free coffee bean so to make decaf the beans are put through a process to remove caffeine. The end result is not caffeine free and it will still contain trace amounts of caffeine, usually between 2-12 mg, for an 8 oz. or 237 ml cup. That small of an amount of caffeine seems very insignificant, and it is, assuming you are not drinking numerous cups of it.

Many herbal teas are caffeine free since herbs, like peppermint, for example, do not naturally contain caffeine. Black and green teas do have caffeine since it is naturally in tea leaves. Tea, which is much lower in caffeine than coffee, can be a good alternative. Not all teas are recommended when you are pregnant. For more in depth info on drinking tea during pregnancy check out this episode.

Caffeine Alternatives

If you want to avoid caffeine, you already know the very best thing for you to drink is water. You know you need to watch caffeine in soda, but there could also be some ingredients in there that are not ideal. These include high amounts of sugar, artificial sweeteners, GMO ingredients if that is something you are concerned about. If you are not into reading the ingredients on everything you eat or drink and you don’t plan to start now, a good rule of thumb is the less ingredients on the label the healthier it is, and if you can easily pronounce the ingredients, even better. 

Finding Solutions that Work For You

Overall 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 you are comfortable doing that you surely can. If you are tired, rather than sip on a cup of caffeine, and power through it, take a nap, go to bed early. When your body is telling you that you need rest, listen to it. Your body will let you know when you need to slow down, but you have to be paying attention to it.

Caffeine is a stimulant and it is not just going to 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 just a short term change. Luckily for you, the research doesn’t say that you have to avoid all caffeine. If you do decide to enjoy a caffeinated beverage, just keep track of how much caffeine you are consuming. 

Caffeine and Blood Glucose Screening

As a side note, since coffee may increase your blood glucose levels you may want to skip a morning cup of coffee before your glucose screening. I have heard that it is possible that it could produce a false positive. This makes sense on the surface, although I didn’t spend time researching this particular item further. To be cautious I would personally not have coffee before a glucose screening, this may be something you want to talk to your doctor or midwife about. 

Talking to Your Doctor or Midwife

This is also a great topic you can bring up with your doctor or midwife to get their opinion on caffeine consumption. Remember they are your trusted partner. You should be talking to them about anything you have questions on.


Thank you to Zahler for their support of this episode. Zahler makes a high quality prenatal vitamin that has the active form of folate plus omega 3s and DHA. This is my favorite prenatal vitamin, the one I take everyday and the one I recommend to all expecting moms. Zahler is offering an exclusive discount to listeners of the Pregnancy Podcast. To check out the vitamin and find out how you can save 25% when you buy a one month supply on Amazon click this link Zahler Prenatal + DHA.

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