between days 4 and 8 ( day 0 = ovulation ) of pregnancy , guinea pigs were prepared for the simultaneous in situ measurement of ubf , iuph , and iupco2 , and the changes in these parameters were compared to serum levels of 17 beta-estradiol ( e2 ) and progesterone ( p ) .
C0032961
pregnancy
C0033308
progesterone