Creatine and pregnant women: needs, potential benefits and precautions

Creatine is a small molecule that our body naturally produces from three amino acids: glycine, arginine and methionine (amino acids are the building blocks that make up proteins). The liver, kidneys and pancreas produce it every day. It is also found in food, mainly in meat and fish, and in smaller amounts in dairy products. In adult women, the body produces around 1 g per day, while the diet provides the rest, i.e. just under 1 g. The two pathways therefore complement each other to maintain stable levels.

Its main role is to provide energy. Creatine contributes to a system that recharges cells with energy, rather like a backup battery, which is particularly useful in tissues with high and fluctuating energy demands: the muscles, heart and brain. Most of the body's creatine, around 95%, is stored in muscle mass, in women as well as in men.

Even outside pregnancy, women have lower creatine stores than men: their endogenous stores, those the body produces itself, are estimated to be 70 to 80% lower, and they also consume less through their diet. Starting from a lower level, they may potentially have more to gain from maintaining good creatine levels at every stage of their hormonal life: menstrual cycle, period, pregnancy, postpartum and menopause (1).

Pregnancy adds an additional demand. New tissues develop (uterus, placenta), and the fetus needs a constant supply of energy. The data clearly show this (2):

• The creatine level in the mother's plasma is approximately 35% lower than in non-pregnant women, from the first trimester onwards.
• The creatine store in muscle mass increases throughout pregnancy (from around 200 to 233 mmol/kg between the beginning and 36 weeks), providing an energy reserve for uterine contractions during labour.
• In the fetal brain, the concentration of creatine is more than doubled between the 18th and 40th week. Until an advanced stage, it depends mainly on the creatine its mother passes on through the placenta.

Yet nearly 6 in 10 pregnant women (57.2%) consume less creatine than the recommended intake for an adult woman (3).

This is a common confusion, and one worth clearing up because the two words are very similar.

The creatine is the useful molecule, the one that contributes to energy production in cells.

The creatinine is a waste product: it is what remains once creatine has been used by the muscles. It is eliminated in the urine: the kidneys filter it, then it passes into the urine. In practice, it is most often measured in a blood test (this is called serum creatinine), as its level reflects kidney function.

During pregnancy, it is normal for the level of creatinine in the blood to decrease: the kidneys filter more, so creatinine is eliminated more efficiently in the urine. This renal adaptation is normal, and reference values are in fact lower in pregnant women than outside pregnancy. Lower creatinine on your blood test is therefore generally not a cause for concern, but the normal expression of pregnancy-related adaptations. Your doctor or midwife will interpret it in context. Key point: the "creatinine" measured in a blood test is not the creatine that might be consumed. They are two different things.

In animals, the observed effects are encouraging. Giving creatine to the mother at the end of gestation improves newborn survival after severe oxygen deprivation at birth and protects several organs. The mechanisms are consistent: creatine fuels cellular energy production, has antioxidant properties, and a good blood level limits the accumulation of GAA, a molecule that is toxic to the brain at high concentrations (4).

In humans, studies exist, but they are observational studies, not supplementation trials: they measure creatine in the blood or urine, or assess dietary intake. Their findings are nuanced. A retrospective study involving 287 pregnant women associates higher maternal urinary creatine levels with better baby growth, with greater birth weight and length (5). However, a more recent, prospective cohort does not find this link (6). A recent review lists the theoretical benefits considered: support for energy production, reduction of oxidative stress, support for immune function, higher concentrations in colostrum (the first milk), and, more hypothetically, fewer complications such as prematurity (7)(8).

In healthy adults, creatine is one of the most extensively studied supplements, and its long-term use is considered safe, including for women (9). However, due to the lack of clinical trials during pregnancy, neither the appropriate dose, the ideal timing, nor the long-term effects on the baby are known. Supplementation cannot therefore be routinely recommended: it should be based on an individualised decision, made with your doctor, midwife or dietitian.

If the question arises, keep two points in mind. Creatine monohydrate is the most studied form and is considered the reference. And in the case of kidney-related factors, particularly a history of kidney failure, medical advice is all the more essential before taking it.

Diet remains the first, simple and safe approach. Creatine is found naturally in foods of animal origin: mainly meat and fish, with dairy products containing smaller amounts.

In practical terms, the estimated dietary requirement for adult women is around 0.75 g of creatine per day, with the body producing the other half of what it needs (10). A few reference points:

• A portion of meat or fish (around 100 to 150 g) provides approximately 0.3 to 0.5 g of creatine.
• Herring is the richest food source, followed by pork, beef, salmon and tuna.
• Poultry contains slightly less, while dairy products and eggs contain very little.
• Plant-based foods provide virtually none.

In other words, one to two portions of meat or fish per day generally cover intake, while also contributing to other pregnancy requirements (iron, protein, omega-3).

Some situations can make these intakes more difficult to achieve: first-trimester nausea, aversions to meat (very common during pregnancy), or a vegetarian or vegan diet. In the latter case, your body partly compensates by producing creatine itself, but this is something to discuss with a nutrition professional as part of the broader balance of your diet.

Pregnancy increases creatine requirements: metabolism adapts, muscle stores are replenished, and the foetus depends on the creatine passed on by its mother, particularly for its rapidly developing brain. Research avenues are promising, but no clinical trial has yet confirmed them in pregnant women.

Your diet remains the first lever: one to two portions of meat or fish per day generally cover your intake. If considering supplementation, discuss it with your healthcare professional. And if you see "creatinine" on a blood test, there is no need to worry: it is a marker of your kidney function, different from creatine, and its decrease is normal during pregnancy.