Not All Progestins are Created Equally: Considering Unique Progestins Individually in Psychobehavioral Research

Abstract

Progestins (i.e., synthetic progesterone) used in hormonal contraceptives (HCs) have been developed to mimic endogenous progesterone to inhibit ovulation and prevent pregnancy. Although the physiological side effects of different progestin formulations and administrative routes (e.g., oral pill, injection, skin patch) are well understood, the potential affective and behavioral side effects of various progestins are relatively under-studied. Progestins vary in terms of their dosage, bioavailability, metabolism, and affinity for progesterone and other steroid hormone receptors. Yet, research investigating the effects of these compounds on women’s affect, sex drive, and mate preferences has not systematically accounted for these differences when considering their psychobehavioral side effects. Here, the biological differences between progesterone and progestins, as well as the differences between progestin types, are considered. Research looking at the effects of progesterone and progestins on women’s affect, sex drive, and mating psychology is reviewed, with emphasis on work that has explored differences between progestin types. In this review, we argue that accounting for these unique aspects of progestins is necessary for a comprehensive understanding of the influence of HCs on women. A better understanding of these differences may clarify previous research and inform future studies.