Progesterone concentration and reproduction: An evaluation in pregnant, heat-acclimated, white rats

Abstract 1. 1.|Progresterone concentrations in peripheral plasma, corpus luteum, uterus and placenta were determined by radioimmunoassay, in pregnant heat-acclimated (HA) and control (C) rats. 2. 2.|Concentration of progesterone in plasma and uterus of HA rats were lower than C from day 5 to 18 and day 5 to mid-gestation respectively. 3. 3.|Number and weight of pups born to HA rats were lower than C by 11.1% and 12.3% respectively. 4. 4.|It is concluded that aberration in pregnancy development observed in HA rats is associated with lower progesterone concentration in plasma and uterus from day of implantation to mid-pregnancy.