High serum progesterone associated with infertility in a woman with nonclassic congenital adrenal hyperplasia

Nonclassic congenital adrenal hyperplasia (NCAH) is an autosomal‐recessive disorder caused by 21‐hydroxylase deficiency and manifests as hirsutism and oligomenorrhea due to excess adrenal androgen and progesterone. We report a case of a woman with NCAH who showed continuous high serum progesterone levels in the follicular phase associated with impaired folliculogenesis. NCAH was diagnosed based on high 17‐hydroxyprogesterone levels after rapid adrenocorticotropic hormone loading, and three heterozygous missense mutations in CYP21A2, encoding 21‐hydroxylase, were identified. Recurrent failure of in vitro fertilization programs occurred because of empty follicles and preterm rupture of leading follicles, and vaginal stenosis with a hypoplastic cervix. Glucocorticoid administration normalized serum progesterone levels, restored folliculogenesis, and stretched the vaginal wall, which contributed to the success of the in vitro fertilization program. The patient delivered at term following blastocyst transfer. Correction of hyperandrogenism and high progesterone levels using glucocorticoids may improve fertility in women with NCAH.