The importance of progesterone in pregnancy establishment in cattle

Abstract

Progesterone (P4) plays a key role in reproductive events associated with the establishment and maintenance of pregnancy through its effects on oocyte quality and its action on the uterine endometrium. Reduced P4 concentrations during growth of the ovulatory follicle are associated with lower fertility, while low concentrations of circulating P4 after ovulation have been associated with a reduction in conceptus growth and elongation, a decrease in interferon-tau production and lower pregnancy rates in cattle. In contrast, elevated concentrations of circulating P4 in the immediate post-conception period have been associated with an advancement of conceptus elongation, an increase in interferon-tau production and, in some cases, higher pregnancy rates in cattle. Despite the potential beneficial effects of exogenous P4 supplementation on fertility, results of supplementation studies have been inconsistent. This article highlights some of the recent findings in relation to embryo maternal interaction during bovine pregnancy establishment and the role of P4 in in uterine biology and embryo development.