April 15, 2024 12 min read

Are Pre-Workout Supplements Safe During Pregnancy

For centuries, it was believed that once a woman was with child, she was expected to be essentially confined from the world and endure a month’s long laying-in period of abject inactivity. We now know that extended periods of inactivity, especially while pregnant, can lead to decrements in strength, cardiovascular fitness, flexibility, and endurance, while also potentially predisposing one to gestational diabetes and excessive weight gain. Pregnancy can be thought of as a marathon, and preparation can equip you for the journey and the finish line! In the pursuit of maintaining healthy weight gain and fitness, caution must be exercised (pardon the pun), in not only what and how much one should workout, but in the consumption of performance enhancing supplements. Are they safe, and are there acceptable alternatives?

What is pre-workout?

Pre-workout is an ergogenic, or performance enhancing dietary aid, which is generally composed of multiple ingredients, and is to be ingested approximately 30-60 minutes prior to exercise. They contain ingredients such as specific amino acids, vitamins and caffeine, which enhance energy, strength and blood flow while improving focus and attenuating fatigue to enhance workload and performance. Pre-workout supplements may come in liquid, capsule and powder form.

Typical pre-workout ingredients

Pre-workout products, which usually come in powdered form, contain filler ingredients to enhance taste and palatability such as sugar, sugar alternatives, stevia, natural or artificial colors, taste enhancers, desiccants and preservatives. The following is a list of some common active ingredients, though certainly not comprehensive, as different companies and manufacturers have their own formulations.


The majority of pre-workout supplements contain caffeine, which is one of the most well-studied performance enhancing substances. Caffeine has been proven to enhance focus and cognitive function, reduce perceived fatigue, and improve athletic power for anaerobic and aerobic exercises, alike. Other herbs may also be included, sometimes as a proprietary blend, which also contain naturally-occurring caffeine and other alkaloids that may have synergistic, energy-inducing effects.

Creatine monohydrate

Creatine is a naturally occurring chemical found in cells that is an integral part of cellular metabolism and in the phosphocreatine system. Essentially, when muscles are working too intensely for the oxygen-delivering aerobic system to break down glucose into ATP (adenosine triphosphate) at a rate that matches muscular demand, an alternative is required. The energy currency of the cell, ATP, is necessary for literally every active process in all cells, hence, its importance in exercise physiology and supplementation. The phosphocreatine system serves as this required alternative. Creatine transfers a phosphate to replenish the active ATP from the inactive form, ADP (adenosine diphosphate). Creatine has been proven to have utility in intense, anaerobic exercises for increasing power, muscle mass and reducing muscle fatigue, soreness and damage. 


Interestingly, another amino acid that is typically found in pre-workout supplements, called betaine, may increase creatine synthesis through certain methylation reactions. Betaine also increases nitric oxide production, maintains fluid balance in cells, and may reduce fatigue and allow for more strength-based repetitions with repeated supplementation. 

Beta alanine

Beta alanine is a non-essential amino acid that synthesizes carnosine in cells. Carnosine is a dipeptide comprised of alanine and histidine and is responsible for neutralizing reactive oxygen species or free radicals, that damage cells. In muscles, this is especially useful, as rapidly contracting muscles consume a lot of energy and produce free radicals, naturally, by virtue of normal cell metabolism. It also reduces muscle fatigue and damage as it acts as a buffer to reduce acidity that accumulates from high intensity exercise.


Branched chain amino acids are a typical mainstay in pre-workout concoctions, and it is composed of the three amino acids: leucine, valine and isoleucine. There is inconclusive evidence to suggest they may reduce muscle fatigue and pain, but they do not seem to have any significant impact on performance

Nitric oxide precursors

Nitric oxide is a necessary, physiological compound that we must consume and is produced endogenously, by the lining of the blood vessels. Nitric oxide actually helps promote enhanced blood flow via the relaxation of smooth muscles within the vessels. This widens the diameter of the arteries and allows more blood through at a lower pressure. The utility of this is self-evident in the context of physical activity. Many pre workout blends contain beetroot powder, as it is a natural and robust source of nitric oxide. Typically, they may also contain the amino acids, L-arginine and L-citrulline as well. Citrulline is converted to arginine, which is then oxidized to nitric oxide.

B vitamins

The B vitamins are water soluble, and several of the thirteen are often included in pre workout drinks for their various metabolic functions. Toxicity is unlikely, as an excessive consumption of these water-soluble vitamins can simply be removed via urination. These B vitamins typically found in pre-workout supplements may include folic acid, vitamin B12, thiamine, pyridoxine and niacin. In a general sense, B vitamins are responsible for energy use and metabolism of amino acids, fat and carbohydrates (they are cofactors in many metabolic enzymes), the creation of RNA and DNA, synthesizing red blood cells and creating certain neurotransmitters. Supplementation with these actually has been shown to decrease the concentration of lactic acid and ammonia (markers of muscle fatigue) and improve endurance performance.

Potentially dangerous in pregnancy

Unfortunately, in pregnancy, pharmaceuticals and supplements are not usually tested on pregnant and nursing women. Not only are women more vulnerable to disease and injury as compared to age-matched non-pregnant women, but their fetuses are also as well. Therefore, there are many recommendations against certain activities, and consuming certain supplements and medications. The consumption of pre-workout supplements has, in rare cases, caused heart attacks, palpitations, hemorrhagic stroke, digestive distress, and acute kidney and liver injury in average, non-pregnant persons. In fact, most of these supplements have warnings for caution or avoidance if one has liver or kidney diseases, heart diseases, are on blood thinners, or are indeed pregnant or breastfeeding. Clearly, caution should be exercised, especially during this special time while you are growing another human being inside of you.

Pre-workout is one such supplement that is generally discouraged, as some ingredients pose known risks, and others for those whose impacts are unknown and thus best to be avoided. Caffeine is a well-studied drug, even in pregnancy. Most likely because it is so commonly consumed and ubiquitous in our society, through coffee, tea, chocolate and dark colas. Though coffee is healthy in moderation, it poses a potential risk to a developing embryo or fetus in utero. The latest recommendations for caffeine intake during pregnancy, is a max of 200 mg per day. This is the equivalent of two cups of coffee, or one coffee and two teas. Caffeine is a central nervous system stimulant, and it tends to increase heart and breathing rate via a release of catecholamines such as epinephrine. Like the blood brain barrier, caffeine also can freely cross the placental barrier, and causes increases in fetal heart rate variability and placental vasoconstriction, which impedes blood flow to the fetus. This has been shown to increase the risk of having a small gestational age fetus and growth impairments at consistently high quantities. It is worthy to note here, that throughout pregnancy, your cardiac output and blood volume doubles, placing stress on the heart. Consider this extra demand on the heart, as well as the increased cardiovascular demand of exercise and caffeine, when deciding to take and in selecting which supplements are right for you.

Individual amino acid supplementation without being specifically prescribed by a qualified physician, is generally discouraged due to unknown risks. Using rodent studies as a proxy for human fetuses, pregnant mice gave birth to smaller than normal litters when supplemented with BCAA’s. Clearly, we are not rodents, but the recommendations remain out of an abundance of due caution. In another study assessing pregnant women in China, BCAA supplementation in early pregnancy actually increased the risk of gestational diabetes.

What supplementation is acceptable during pregnancy?

As was stated, care must be taken when deciding on a pre-workout supplement. Furthermore, it is paramount that you consult your physician/obstetrician prior to taking anything; even natural supplements and vitamins may be hazardous and are certainly not health neutral. Below is a list of acceptable and generally safe ingredients you may consume during pregnancy.


Supplements, such as Mamasupps, are formulated especially for pregnant women. These contain about half of the recommended daily caffeine limit during pregnancy, at 100mg per serving. As such, other caffeinated supplements or beverages should not be consumed near the time you are to consume a pre-workout. 


Mamasupps pre-workout supplements do not contain any obscure, potentially harmful herbs or additives either. Instead, they contain small amounts of electrolytes such as sodium chloride (table salt), potassium, magnesium, and calcium citrate. During moderate to intense physical activity, fluid and electrolyte requirements need to be considered, especially during pregnancy, and are vital for the following functions:

  • Maintain fluid homeostasis both intracellularly (within the cell), and intercellularly (spaces in between the cells). 
  • They are also indispensable for muscular contraction and relaxation
  • Serve as ions necessary for nervous transmission.

Due to the increased blood volume and normal cardiovascular perturbations during pregnancy, you may experience lightheadedness. For this reason, you should avoid activity while hungry or dehydrated.


Magnesium, which is also found in nuts, seeds, whole grains and vegetables, helps relax the smooth muscle within arteries resulting in a vasodilatory effect. Magnesium is actually used to induce relaxation, to treat hypertension or high blood pressure indicative of pre-eclampsia, as well as gestational diabetes by regulating blood sugar levels. 


The calcium citrate Mamasupps contains, is highly bioavailable, and in addition to its role in nerve conduction and muscular contraction, is important in calcifying bones. Calcium needs are slightly elevated during pregnancy, and this pre-workout supplement helps one attain their daily requirements. Good calcium sources include dairy, dark leafy vegetables, tofu, canned fish with bones, and nuts.


In addition to electrolytes, this pre-workout, specifically marketed for pregnancy, also contains choline. Choline is found naturally in egg yolks, dairy, meat, fish, beans, cruciferous vegetables (broccoli, cauliflower etc.), nuts and seeds. Choline is needed to create phospholipids that comprise the lipid membranes of cells, the neurotransmitter acetylcholine and fetal brain development. A deficiency has been shown to increase the probability of neural tube defects.

Vitamin C

Vitamin C is also included in the Mamasupps formulation and can also be found in foods such as citrus fruits, strawberries, peppers and leafy vegetables. Vitamin C needs are increased during pregnancy because of tissue anabolism, or the increase in the building of tissue for both mom and fetus. Vitamin C is also necessary to build collagen in skin, bones and organs, it is an antioxidant, helps with wound repair, immunity and helps you absorb iron. 

B vitamins

Some of the necessary B vitamins are also included in this supplement, as it is in most energy drinks and pre-workout supplements. These include vitamin B12 and B6 or pyridoxine. Vitamin B6 is actually necessary for fetal brain development and neurotransmitter synthesis, and metabolism. Foods that are particularly rich in B6 include animal products, nuts and legumes. Vitamin B12 is another vital B vitamin important for the creation of red blood cells, RNA and DNA synthesis, as certain enzymatic cofactors, and for the creation of the myelin sheath that surrounds nerve axons (responsible for the propagation of nerve signals). Deficiencies of vitamin B12 during pregnancy can result in spontaneous abortion, low birth weight, neurological disorders and pre-eclampsia in the pregnant individual. This, like many nutrients, is needed at a slightly higher quantity during pregnancy, especially given the increased requirements for red blood cell production for both mom and fetus. 

Nitric oxide 

Additionally, Mamasupps also contain beet root powder, and the nitric oxide amino acid precursors citrulline and arginine. As was discussed, these contribute to vasodilation, which helps improve exercise performance and is vital for a healthy, functioning cardiovascular system. There are preclinical, animal rodent models where they experimentally induced a preeclampsia like condition marked with high blood pressure and assessed whether these amino acids could provide benefit. The results suggest a maternal and fetal vascular benefit in  improving blood flow. Other than beets, other leafy greens are also rich in nitric oxide.

Selecting supplements

When selecting a pre-workout supplement, it is a good idea to think critically, shop around and take into consideration some important factors:

  • Try to select a third-party approved product. This means that the product has gone through rigorous safety and chemistry testing to ensure that the ingredients listed are actually contained in the formulation, and in the quantities listed. They also make sure that there are no hidden ingredients not divulged in the nutritional facts.
  • In follow up to the previous point, the US FDA, like numerous other countries, have lax safety and chemistry testing requirements for validating the fidelity of the ingredients claimed on the product label, prior to being placed on the market. This has occasionally resulted in products containing illegal and potentially dangerous or lethal stimulants, heavy metals or anabolic steroids. At best, sometimes this has resulted in the product simply containing less than the active ingredient listed, or not at all. This should be alarming to anyone, but in pregnancy, one must be especially cautious.
  • Avoid supplements that fail to provide distinct quantities, or those that say, “proprietary blends”. This can be an insidious marketing tactic that serves to fool the consumer by not being honest about what and how much of those ingredients are within, like a mystery bag.
  • Avoid high quantities of caffeine or other caffeine-containing herbs as these have been linked to insomnia, heart palpitations, headaches, anxiety, stroke and heart attacks.
  • Consider that in rare circumstances, acute kidney and liver injury has occurred after the consumption of these products, although the direct causes are unknown.
  • Always follow the directions listed by the manufacturer, stringently. 
  • Consult a physician prior to using one.
  • Discontinue immediately if you notice any deleterious side effects.

Importance of physical activity

Moderate activity during pregnancy, barring any contradictory stipulations recommended by your physician, is very important during pregnancy. Though this isn’t the time for major strength gains, and pushing yourself to the max. Instead, the goal should be in maintaining strength, endurance and flexibility. This is important for heart health, and to ensure a healthy weight gain during pregnancy while also helping to stimulate appetite, improve sleep, mobility and alleviating constipation which is common in pregnancy. Regular exercise also helps to lower blood pressure, reduce the probability of developing gestational diabetes, alleviate lower back and pelvic pain, and reduce the incidence of macrosomia (larger than average baby). 

To be safe, you should take heed of certain limitations while exercising and which activities to avoid, including:


  • Avoid laying in a prone position, and for that matter, in a supine position flat on your back during the second trimester. Laying on your back as your belly grows compresses the vena cava and hence, impedes circulation back to the heart.
  • Avoid engaging in contact sports, gymnastics, cycling, horseback riding or any other activity that incurs a reasonably high chance of falling.
  • Avoid overheating, dehydrating, exercising while hungry, in the heat, or activities that are too intense for you to be capable of carrying on a conversation. 
  • Cease activity if you experience vertigo, lightheadedness, spotting or pain.

Final remarks

Pre-workout supplements during pregnancy can be acceptable if you consider consulting your physician and making sure you are a critical consumer by paying strict attention to the ingredient list. Avoiding excessive amounts of caffeine, other caffeine-containing ingredients, excessive amounts of sugar, herbs and selecting those that are third-party verified, are all important safety factors to consider. Seeking out formulations for women and pregnant women, such as Mamasupps may be beneficial, as many performance enhancing supplements are generally marketed towards men. Instead, select ingredients that include vitamins, nitric oxide and nitric oxide-producing amino acids like arginine and citrulline to promote good circulation, and electrolytes to replenish those lost in urine and sweat. 


Armitage, M. (2024). What does preworkout do? benefits, risks, and more. GoodRx. https://www.goodrx.com/well-being/movement-exercise/what-does-preworkout-do 

Brown, B., & Wright, C. (2020, October 1). Safety and efficacy of supplements in pregnancy. Nutrition reviews. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7558284/ 

Cervoni, B. (2021). Is it safe to drink energy drinks during pregnancy?. Verywell Family. https://www.verywellfamily.com/is-it-safe-to-drink-energy-drinks-during-pregnancy-4689931 

Cinelli, E. (2022, April 14). Can I take amino acids while pregnant?. Verywell Family. https://www.verywellfamily.com/are-amino-acids-safe-in-pregnancy-89167#citation-4 

Gemmel M, Sutton EF, Brands J, Burnette L, Gallaher MJ, Powers RW. l-Citrulline supplementation during pregnancy improves perinatal and postpartum maternal vascular function in a mouse model of preeclampsia. Am J Physiol Regul Integr Comp Physiol. 2021 Sep 1;321(3):R364-R376. doi: 10.1152/ajpregu.00115.2020. Epub 2021 Jul 14. PMID: 34259017.

Harty, P. S., Zabriskie, H. A., Erickson, J. L., Molling, P. E., Kerksick, C. M., & Jagim, A. R. (2018, August 8). Multi-ingredient pre-workout supplements, safety implications, and performance outcomes: A brief review - journal of the International Society of Sports Nutrition. BioMed Central. https://jissn.biomedcentral.com/articles/10.1186/s12970-018-0247-6#Sec3 


Lakin H, Sheehan P, Soti V. Maternal Caffeine Consumption and Its Impact on the Fetus: A Review. Cureus. 2023 Nov 4;15(11):e48266. doi: 10.7759/cureus.48266. PMID: 37929268; PMCID: PMC10625456.


Lee, M.-C., Hsu, Y.-J., Shen, S.-Y., Ho, C.-S., & Huang, C.-C. (2023, August 15). A functional evaluation of anti-fatigue and exercise performance improvement following vitamin B complex supplementation in healthy humans, a randomized double-blind trial. International journal of medical sciences. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10542023/#:~:text=B%20vitamins%20are%20involved%20in,metabolism%2C%20and%20exercise%20performance%2025. 


Li, N., Li, J., Wang, H., Liu, J., Li, W., Yang, K., Huo, X., Leng, J., Yu, Z., Hu, G., Fang, Z., & Yang, X. (2022b, June 16). Branched-chain amino acids and their interactions with lipid metabolites for increased risk of gestational diabetes. The Journal of clinical endocrinology and metabolism. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9891107/ 


Martinho, D. V., Nobari, H., Faria, A., Field, A., Duarte, D., & Sarmento, H. (2022, September 27). Oral branched-chain amino acids supplementation in athletes: A systematic review. Nutrients. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9571679/ 


Mottola, M. F., Davenport, M. H., Ruchat, S.-M., Davies, G. A., Poitras, V. J., Gray, C. E., Garcia, A. J., Barrowman, N., Adamo, K. B., Duggan, M., Barakat, R., Chilibeck, P., Fleming, K., Forte, M., Korolnek, J., Nagpal, T., Slater, L. G., Stirling, D., & Zehr, L. (2018, November 1). 2019 Canadian guideline for physical activity throughout pregnancy. British Journal of Sports Medicine. https://bjsm.bmj.com/content/52/21/1339 

Ronald L. Snarr, P., Gallagher, C., Childers, R., Alyssa Lauren West, C., & Eisenman, M. (2021, October 8). Pre-workout supplementation – the good, the bad, and the ugly. National Strength and Conditioning Association (NSCA). https://www.nsca.com/education/articles/ptq/pre-workout-supplementation/

Shrimanker I, Bhattarai S. Electrolytes. [Updated 2023 Jul 24]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK541123/

logo-paypal paypal