Copper in pregnancy: evidence and safety

How does copper work?

Copper works as a cofactor rather than as an active agent. NIH ODS describes it as a cofactor for several enzymes, the cuproenzymes, involved in energy production, iron metabolism, neuropeptide activation, connective tissue synthesis, and neurotransmitter synthesis. It is also involved in angiogenesis, neurohormone homeostasis, and the regulation of gene expression, brain development, pigmentation, and immune system functioning, and the body's defense against oxidative damage depends mainly on the copper-containing superoxide dismutases. None of that is pregnancy-specific, which is why the pregnancy question here is about adequacy and about the zinc interaction rather than about any mechanism unique to being pregnant.

What does the evidence say about copper in pregnancy?

• The RDA is 1,000 mcg a day during pregnancy and 1,300 mcg during lactation, against a tolerable upper intake level of 10,000 mcg for adults 19 and older. Beef liver carries 12,400 mcg in a 3-ounce serving, which is one reason liver is limited in pregnancy for other reasons too. 1
• High dietary zinc interferes with copper absorption, and excessive zinc supplements can drive copper deficiency. The effect has been documented at roughly 60 mg of zinc a day for up to 10 weeks. 1
• The Institute of Medicine makes no recommendation for routine prenatal copper supplementation, noting pregnant women typically consume 1.4 to 1.8 mg a day already. It does advise that a 2 mg copper supplement accompany any zinc supplement given in pregnancy. 2
• In a Malawian case-control study, mean maternal serum copper was 2.61 mg/L in spontaneous preterm births versus 2.39 mg/L in term births (p = 0.004), but the association no longer reached significance once the analysis adjusted for other variables. 3
• A 2021 review proposing an optimal prenatal formula suggested 1.3 mg of copper daily against a 10 mg upper limit, arguing that low copper in early pregnancy is a risk factor for spontaneous abortion and central nervous system malformations. 4

What's on the label?

ODS lists cupric oxide, cupric sulfate, copper amino acid chelates, and copper gluconate as the forms sold, and states plainly that no studies have compared the bioavailability of copper across them. Supplement amounts range from a few micrograms up to 15 mg, roughly 17 times the Daily Value, so the milligram figure on a panel tells you far more than the form name does.

What should I know before taking copper?

Please consult your healthcare provider before adding this supplement to a prenatal regimen, particularly if you are on prescription medication or have a scheduled procedure. Supplement contents are not FDA-verified, so a labeled dose and an actual dose can differ; look for third-party-tested brands.