Kuan Lee 
Fetal heartbeat irregularities might be more common than you think.
Although you should always get your concerns checked out, most times, it’s nothing to be worried about.
Still, any changes in your baby’s heartbeat can be scary. You’re not sure if they’re okay or what you should do about it.
If your doctor detects these changes, they may guide you to pay attention to the substances you’re using. Without knowing it, products containing caffeine can change your baby’s heartbeat.
Read on to learn 8 products that can cause fetal heartbeat irregularities.
What’s an Irregular Fetal Heartbeat?
An irregular fetal heartbeat deviates from what is normal. Although your baby’s heartbeat will change as they develop, some differences can be alarming.
An irregular fetal heartbeat—or fetal heart arrhythmia—can fall into a few categories:
- Heartbeat too fast
- Heartbeat too slow
- Abnormal rhythm
If you think your baby has an irregular heartbeat, you should contact your doctor. If they also suspect an issue, they’ll probably refer you to a specialist. You might have to do several tests to confirm whether there’s a congenital heart defect causing the abnormality.
Although you should have any concerns checked out by your doctor, most irregular heartbeats are caused by lifestyle factors. Research shows that irregular fetal heartbeats only indicate a serious problem a fraction of the time.
8 Substances that Cause Irregular Fetal Heartbeat Third Trimester
Many times, healthcare providers will ask about the substances an expectant mother is using. Through this review, they can usually spot the trigger. If you’re unsure, it might help to note down when you use any of these substances—and how much.
These products may cause fetal heartbeat abnormalities during the second or third trimesters of pregnancy.
#1 Coffee
As you may notice, caffeine can cause your heart to race—it’s what gives you an energy boost. Unfortunately, though, that effect may be passed onto your baby. Too much caffeine can make a fetal heartbeat increase.
One study found that high caffeine intake could increase your baby’s catecholamines, which are released into the blood when someone is physically or emotionally stressed. In turn, this might cause an increased heart rate.
This is just one reason why coffee is a substance to limit during pregnancy. Other evidence links it to a heightened risk of negative pregnancy outcomes. A 2014 paper reviewed 13 studies and concluded that increased caffeine intake was associated with low birth weight risk.
Compared to other forms of caffeine, coffee might pose an increased risk. A large cohort study found that coffee was linked to increased gestational length. The same was not true for caffeine. However, they found that all caffeine forms were associated with low birth weight in this study too.
Other early research suggests that the substance may affect children as they grow up and may impact future generations. To learn more, read Caffeine During Pregnancy: Your Complete Guide to Drinking It During All Trimesters.
All of this research has led experts to one conclusion: Pregnant women should stick to one cup of coffee per day. More specifically, they should limit themselves to no more than 200mg of caffeine per day. This is important to note because coffee brands have varying levels of caffeine.
If you’re sticking to this caffeine guideline and are still experiencing irregular heartbeats, your doctor may ask you to try:
- Counting caffeine milligrams— You might think you consume under 200mg of caffeine a day but in reality, you could be far surpassing it. This could be the case when you drink a different brand of coffee. Try to notice patterns. For example, maybe your baby only has an irregular heartbeat on days you go to Starbucks instead of making coffee at home. This could be because Starbucks is more caffeinated or that their “small” size is bigger than yours at home.
- Further reduce coffee intake— Even if you’ve already cut down your coffee intake during pregnancy, you might need to split it in half again. Perhaps you’re sticking to the caffeine guideline but your body is just sensitive to its effects. A good way to test this is to drink less or stop drinking coffee altogether and see if the problem continues.
#2 Tea
When adding up your caffeine intake, make sure to include tea into your count. Although it typically contains less, a few cups could send you over the limit, possibly causing irregular fetal heartbeats.
Each tea contains a different amount of caffeine, so be sure to check the label and never assume. To give you an idea, one brand of black tea may be 20mg a cup while another could be 90mg. The differences among tea types vary even wider. In comparison, a white tea could be as low as 15mg per cup.
If your baby has an irregular fetal heartbeat, you might want to play it safe and stick to herbal teas, which are naturally uncaffeinated. Not all herbal teas are safe though. Some contain plants that haven’t been proven safe during pregnancy. Before choosing a tea, make sure to research the herb’s effects on a fetus.
#3 Soda
Caffeine is also found in high amounts in sodas.
Some flavors, such as Brisk Peach Tea, only contain 8mg. However, Pepsi contains about 38mg per can. Drinking a few throughout the day may lead to changes in your heartbeat and your baby’s.
If you’re looking for a caffeine-free alternative, you can try Sprite or 7-Up.
#4 Dark Chocolate
There is also a small amount of caffeine in dark chocolate, making it necessary to add to your daily limit count.
One study showed that cocoa had a stimulating effect on fetal reactivity. This is likely due to theobromine, which is also present in coffee.
Given this, we may assume that eating large amounts of chocolate—or small amounts with other caffeine sources—could cause fetal heartbeat abnormalities.
#5 Energy Drinks
If the small amount of caffeine in dark chocolate can impact you, you can assume an energy drink will too.
Whether it’s Red Bull, Monster or an energy shot, they aren’t healthy for the average person and they’re especially unwise during pregnancy. Although the fatigue symptoms can make it tempting, just one can may contain 160mg of caffeine. Expecting mothers should also consider the other unsafe ingredients that could be lurking in some brands.
One study concluded that energy drinks shouldn’t be consumed during pregnancy because they may have a negative impact on newborns. Authors said it should be “treated as a significant health problem that warrants attention.”
#6 Migraine Medications
Migraine medications often contain caffeine. That’s because the substance can help ease pain. The benefit could also lead to a drawback during pregnancy: It may cause irregular heartbeats.
This is why it’s important to tell your doctor about any medications you’re taking while expecting. Although they may not advise you to stop taking it, they can warn you about problems to watch for.
If you’re on migraine medication and are having irregular fetal heartbeats, your doctor may switch your medication to see if it’s the cause. Don’t start or stop taking any medication without the advice of your healthcare provider.
#7 Cocoa Butter Creams or Lotions
Out of all the substances on this list, you’ll probably suspect this one the least. Cocoa butter products can have a significant amount of caffeine in them, possibly triggering heartbeat abnormalities. Since the moisturizer is often used during pregnancy to prevent stretch marks, it could be a cause to consider.
One study showed that cocoa butter is linked to isolated fetal premature atrial contractions (PACs).
Although these creams are typically safe to use, your body might be more sensitive to their effects. More likely, since it only contains a small amount, it could have pushed you over your limit in combination with other caffeine sources.
To test out whether it’s causing an abnormal heartbeat, your doctor may ask you to use a different product.
#8 Nicotine
Smoking during pregnancy is dangerous for numerous reasons, including the risk of an abnormal heartbeat. This possibility also extends to other forms of nicotine, such as vaping.
If you’re having trouble quitting nicotine while pregnant, contact your doctor ASAP for resources.
Do Fetal Dopplers Detect Irregular Fetal Heartbeats?
Fetal Dopplers are devices that allow you to hear your baby’s heartbeat from home. You can also see their fetal heart rate on the display screen.
If you use a fetal heartbeat monitor correctly, you may begin seeing patterns and finding out what’s normal in your baby’s heartbeat. When something seems off, you may contact your midwife or doctor who can confirm or deny the issue.
Although fetal dopplers can detect irregular fetal heartbeats, only a trained healthcare professional can diagnose and treat problems.
