Why this happens

1. Folic acid has the strongest evidence base of nearly anything on this page: large randomized trials from the early 1990s established that 400mcg–800mcg of folic acid daily, started before conception, cuts neural tube defect risk substantially — this is the evidence that led to mandatory food fortification in dozens of countries. Methylfolate (5-MTHF) is marketed as superior, particularly for the estimated 30-60% of women with MTHFR gene variants that reduce folic acid conversion. Recent randomized trials confirm methylfolate maintains folate status while producing less 'unmetabolized folic acid' in the blood — a real, measurable difference. But no randomized trial has directly tested methylfolate against folic acid for the outcome that actually matters — neural tube defect prevention — and one such trial would be considered unethical to run, since it would mean withholding folic acid's proven benefit from half the participants. So the honest state of the evidence: folic acid has decades of outcome data; methylfolate has good biomarker data but no head-to-head outcome trial. Either is a reasonable choice; treat 'methylfolate is scientifically superior' marketing claims with some skepticism.

   Important: the 2026 Frontiers RCT on methylfolate was funded by Ritual, a prenatal vitamin brand. The authors are legitimately university-affiliated (Brooklyn College CUNY, Cornell), but this is manufacturer-funded research, not an independent comparison — treat the methylfolate findings with that in mind. (No specific brand is recommended in this category's buy-guide on the basis of this study.)

2. Choline is the clearer miss. A randomized trial found prenatal choline supplementation measurably improved how the body uses supplemental DHA, working through a specific metabolic pathway (PEMT) that's especially active in pregnancy. Most standard prenatals simply don't include enough to matter, which is a formulation choice, not a scientific one — choline is bulky, so a multivitamin can't fit a full 450mg dose into one reasonably-sized pill alongside everything else.

3. DHA is worth a candid note too: despite heavy marketing around fetal brain development, a Cochrane review and multiple large randomized trials found DHA supplementation has little consistent effect on child cognitive outcomes specifically, though it may modestly reduce preterm birth risk. It's not wasted, but the 'smarter baby' framing oversells what the trials actually show.