Can I Take Marine Collagen Supplements While Pregnant?

I’m pregnant with my second donor-egg-conceived baby and wanted to know about marine collagen supplements in pregnancy. Having been in perimenopause since my early 30s, I started taking supplements last year, and they have helped with hair growth and skin and a little with aching joints. Some sources say they are safe, but others suggest marine collagen may have heavy metals in it and it’s safer to not take them. Is there any data on this?
—Early-aging mum of one

Decreases in estrogen during perimenopause and menopause lead to decreased collagen levels in skin and bone. This can lead to aging and wrinkling of skin. Marine collagen has been associated with some improvement in aging skin. One randomized study of women in their mid-50s on average showed a reduction in wrinkles and improvements in elasticity and hydration after 12 weeks of taking marine collagen.

Marine collagen is largely derived from byproducts of the fishing industry, especially fish skin and scales. Mercury largely accumulates in fish organs and muscle tissue, but it can be found in every part of the fish. While there is little data on mercury in marine-derived collagen, one study of collagen derived from big-eye tuna showed no measurable heavy metals.

There is wide variability in mercury content from one fish to another even within species. And it is difficult to know how a marine-derived collagen supplement would equate to the recommendations around fish consumption in pregnancy, which include completely avoiding fish high in mercury.

Additionally, blood estrogen levels in pregnancy are high. This is true no matter how you become pregnant and regardless of your hormonal status prior to pregnancy. This is one reason why many women report improvements in hair, skin, and nails during pregnancy. The benefits of collagen supplements are not well studied in pregnancy or even in younger women, who would typically have higher estrogen levels. It is not clear if there is any benefit to taking marine collagen in pregnancy.

The upshot: There is no data on the safety of marine collagen in pregnancy, and the benefits in women outside of menopause have not been studied. I would probably skip it during pregnancy.