Are lead in prenatal vitamins safe during pregnancy?

What does the evidence say about lead in prenatal vitamins during pregnancy?

1. A study of 26 prenatal vitamin brands sold at retailers found lead in all 51 samples tested, and 14 of the 26 brands, over half, exceeded the 0.5 microgram-per-day safety threshold, with one product reaching 4.0 micrograms a day. 1
2. Cumulative intake of a prenatal supplement over many months may add up to a significant source of toxic element exposure for both mother and baby, and the study's authors called for more industry testing and government oversight of these products. 1
3. First-trimester lead exposure was the strongest predictor of poorer infant cognitive scores, with a 3.5-point reduction in mental development scores at 24 months for every one-standard-deviation increase in first-trimester maternal plasma lead, a bigger effect than exposure later in pregnancy. 2
4. A 2025 review of heavy metals in herbal supplements found that supplements can generally reach the market without the same safety and efficacy evidence required of medicines, and permitted heavy-metal limits for supplements are often less strict than those applied to pharmaceutical-grade products, helping explain why contamination levels vary so much between brands. 3
5. In a randomized placebo-controlled trial, calcium supplementation during pregnancy was associated with an average 11% reduction in blood lead levels, and the effect was even larger (up to 24%) among women who took at least 75% of their calcium doses as directed. 4

Is lead in prenatal vitamins safe in each trimester?

• First trimester. This is the trimester where lead exposure has shown the clearest measured effect on infant cognitive scores in research, so it's the most important window to pick a well-tested prenatal and keep up your calcium intake.
• Second trimester. In one trial, calcium supplementation's protective effect on blood lead was strongest in the second trimester, a 14% reduction versus placebo, reinforcing why pairing your prenatal with adequate dietary calcium matters through this stage.
• Third trimester. The same trial found a smaller but still present 8% reduction in blood lead from calcium supplementation in the third trimester, so continuing a calcium-rich diet or supplement through delivery still has a documented benefit.