The maintenance of trophoblast stem cell population is critical for supporting its differentiation into different trophoblast cell lineages supporting placenta function.[54] The markedly reduced trophoblast precursors at E10.5 in PCOS‐mouse placentas are consistent with previous findings with reduced proliferation of cytotrophoblasts in women with PCOS.[55] This observed reduction might be attributed to a significant downregulation of genes that contribute to maintaining trophoblast stem cells, including Esrrb, Cdx2, and Elf5. The gene discussed is ESRRB; the disease is polycystic ovary syndrome.