The number is the wrong thing to read first. Start with the form.

If you've shopped for a prenatal in the last two years, you've watched the choline arms race in real time.

One brand lists 75mg. Another lists 200. The newest entrants are pushing 400, 500, 550 — and putting the number on the front of the box. The implied message is straightforward: more choline, better prenatal.

It is not that simple.

The form of choline on the label matters at least as much as the dose. In some cases, it matters more. And most prenatals — including expensive ones, including ones marketed by practitioners — are using a form that the published research is increasingly skeptical of.

This is a guide to what's actually in the choline line of your prenatal, what those words mean, and what the science currently supports.

Why choline matters in the first place

Choline is not optional in pregnancy. It is essential.

It supports fetal brain development, neural tube closure, placental function, and the structural integrity of every cell membrane your baby is building. Multiple Cornell studies (Caudill et al., 2018, 2019) have shown that adequate maternal choline intake during pregnancy is associated with measurable improvements in offspring cognitive performance well into childhood.

The current recommended intake is 450mg per day during pregnancy and 550mg per day during lactation. More than 90% of pregnant women in the U.S. do not meet this number through diet alone.

So the prenatal world is right that choline matters and that most women aren't getting enough. The question is what to do about it.

The three forms you'll see on prenatal labels

There are essentially three forms of choline showing up in prenatals on the market today. They are not interchangeable.

1. Choline bitartrate

The cheapest and most common. Choline bitartrate is a synthetic salt — choline bonded to tartaric acid — produced industrially. It dissolves easily, doses precisely, and costs almost nothing. It dominates the mass-market prenatal category and shows up in many practitioner-recommended brands as well.

In April 2021, a clinical trial published in the American Journal of Medicine studied participants supplementing with choline bitartrate compared to participants getting equivalent choline doses from food sources. The bitartrate group showed significant elevations in trimethylamine-N-oxide (TMAO), a metabolic byproduct that has been associated with increased risk of preeclampsia, gestational diabetes, blood clots, and cardiovascular complications. The food-form arms did not show this elevation.

The study authors recommended halting supplementation with bitartrate in favor of food-form choline.

That was four years ago. Most prenatals on the market still use bitartrate.

2. Choline chloride

A newer synthetic form that some brands have shifted to as an "improvement" over bitartrate. The case for it is mostly negative — it is not bitartrate. It does not have the same TMAO data attached to it because it has not been studied as extensively in pregnancy.

That is not the same as it being safe. The absence of evidence is not evidence of absence, particularly with synthetic compounds in pregnancy. The long-term safety data on choline chloride supplementation in pregnant populations does not yet exist at meaningful scale.

Choline chloride is still synthetic, still bypasses the natural metabolic pathway your body uses when processing food-form choline, and is being marketed largely on the strength of "not being bitartrate" rather than on the strength of its own clinical evidence.

3. Phosphorylcholine and other food-aligned forms

This is the category of choline that exists in the metabolic pathway your body actually uses.

When you eat an egg, the choline arrives bundled inside a larger molecule called phosphatidylcholine. Your body breaks it down, processes it through the liver, and routes the choline to where it's needed — including across the placenta to your baby. Food-aligned forms of choline supplementation enter this same pathway.

Phosphorylcholine — a phosphate-bonded choline molecule — is a metabolic intermediate in this process. It does not raise TMAO. It is significantly more bioavailable than synthetic salts. It is also significantly more expensive to formulate with, which is the practical reason most prenatals don't use it.

This is what Tend uses.

The dose conversation

The current arms race is around the number. 75mg vs. 200mg vs. 550mg. Brands compete on the size of the dose printed on the front of the box.

Two things are true at once.

Yes, dose matters. 90% of pregnant women aren't getting enough choline, period. A trace amount on a prenatal label isn't going to close the gap. The brands that pushed the conversation toward higher doses were responding to a real deficiency.

No, more is not better when the form is wrong. A 550mg dose of choline bitartrate is not equivalent to a 200mg dose of phosphorylcholine. Higher doses of bitartrate produce higher TMAO elevations. The bigger number on the label may be doing more harm than the smaller one.

The right way to think about it is: bioavailable, well-formed dose. A prenatal that gives you 200mg of phosphorylcholine is doing more meaningful work than one that gives you 550mg of bitartrate. The form determines what your body can safely use. The dose, in the context of the right form, determines how close you get to your daily target.

Neither number alone tells you the story.

How to read your label

Find the choline line on your current prenatal. Look at the form listed in parentheses or beside the number.

• Choline bitartrate — the cheap, synthetic form. The form the 2021 study flagged.|
  
  
• Choline chloride — newer, synthetic, less long-term data in pregnancy.
  
  
• Phosphorylcholine, phosphatidylcholine, or "from sunflower lecithin" — food-aligned forms. These are what you want.

If your label doesn't specify the form at all — just lists "choline 200mg" with no parenthetical — assume it's bitartrate. That's the default in the industry.

What Tend uses and why

The choline in Tend is phosphorylcholine. We made the switch as part of our most recent reformulation, and it was the most consequential ingredient decision of the new line.

It is more expensive to formulate with. It does not let us put a 550mg "headline dose" on the front of the box. What it does is deliver choline in a form that enters your body's natural metabolic pathway, supports your baby's neurodevelopment, and does not produce the TMAO elevation that the synthetic forms produce.

We believe this is what the research currently supports. We expect the standard of care in prenatal nutrition to move in this direction over the next several years. Most major brands will eventually follow because the bitartrate position is becoming harder to defend.

In the meantime, you can read your own label. And now you know what to look for.

Studies cited

1. Wilcox J, Skye SM, Graham B, et al. Dietary Choline Supplements, but Not Eggs, Raise Fasting TMAO Levels. American Journal of Medicine, 2021.
2. Caudill MA, Strupp BJ, Muscalu L, Nevins JEH, Canfield RL. Maternal choline supplementation during the third trimester of pregnancy improves infant information processing speed. FASEB Journal, 2018.
3. Bahnfleth CL, Strupp BJ, Caudill MA, Canfield RL. Prenatal choline supplementation improves child sustained attention. FASEB Journal, 2022.
4. Zeisel SH. Nutrition in pregnancy: the argument for including a source of choline. International Journal of Women's Health, 2013.
5. Wang J, Gu X, et al. Gut Microbiota Dysbiosis and Increased Plasma LPS and TMAO Levels in Patients With Preeclampsia. Frontiers in Cellular and Infection Microbiology, 2019.