5β-Dihydroprogesterone (5β-DHP, pregnanedione, or 5β-pregnane-3,20-dione) is an endogenous neurosteroid and an intermediate in the biosynthesis of pregnanolone and epipregnanolone from progesterone.

[6] In accordance with the former action, it has been found to possess anesthetic, anxiolytic, and antinociceptive effects.

[7][5][8][9] 5β-DHP has been found to act as an agonist of the pregnane X receptor (PXR) as well (albeit weakly (EC50 >10,000 μM)),[10] and has been found to regulate uterine contractility through activation of this receptor.

[13][14] A study found that 5β-DHP, but not progesterone, directly bound to and antagonized the oxytocin receptor at nanomolar concentrations, and it was suggested that this may be one of the mechanisms by which progesterone maintains pregnancy.

[16] In any case, 5β-DHP has nonetheless been shown to possess tocolytic effects in animals, and this may alternatively be mediated by activation of the PXR.