Progesterone Concentration in Peripheral Blood Plasma of the Domestic Sow Prior to and during Early Pregnancy

Abstract

Progesterone concentration in plasma was measured in peripheral blood from 12 pregnant and 4 nonpregnant yearling sows. A double isotope derivative procedure was used. The averages were 18.2°1.1 ng./ml. (10⁻⁹ gm./ml.) in 68 samples from pregnant sows as compared to 13.2°1.7 ng./ml. in 24 samples from nonpregnant sows. Progesterone increased from 7.5°1.8 ng./ml. during estrus to 27.2°4.0 ng./ml. 12 to 14 days post-breeding. A maximum concentration of 25.2°2.6 ng./ml. was observed 8 to 10 days post-estrus in the nonpregnant group. Means for the periods 3 to 4 days before estrus, estrus and 2 days after estrus were significantly (P<.01) lower than the means for days 4 to 6, 8 to 10 and 12 to 14 in nonpregnant animals, and from days 4 to 6 up to days 24 to 26 of pregnancy.