Menstrual cycle mating partners during the menstrual cycle; however, those seeking a short-term relationship were more likely to choose a partner with more masculine features than usual. This was found to be the case especially during the woman's high conception risk stage and when salivary testosterone was high. However, when women are in the luteal (non-fertile) phase, they tend to prefer men (and females) with more feminine faces. A preference is also shown for self-resembling faces and apparent health in faces during the luteal phase of the cycle. Apparent health preferences were found to be strongest when progesterone levels were high. Additionally,
Progesterone carboxymethyloxime potassium salt) showed water solubility that was increased by more than four orders of magnitude relative to progesterone (solubility = 9.44 mol/L and 0.0006 mol/L, respectively). In addition, it showed an "in vitro" terminal half-life in rat liver microsomes that was 363-fold longer than that of progesterone (half-life = 795.5 minutes and 2.2 minutes, respectively). As such, P4-3-CMO could have both improved absorption and increased metabolic stability relative to progesterone. However, the compound has not been further assessed nor studied in humans. Progesterone carboxymethyloxime Progesterone carboxymethyloxime, or progesterone 3-("O"-carboxymethyl)oxime (P4-3-CMO), is a progestin which was never marketed. It is an