Indwelling catheters were placed in 7 ewes and lambs in utero at approximately 120 days of gestation. Blood was sampled periodically up until the time of parturition and analyzed for progesterone, cortisol, testosterone and 17β-estradiol. Plasma progesterone in the ewe decreased from a level of 8 ng/ml 4-5 days prior to parturition to a level of 1 ng/ml on the day of delivery. In the fetal lamb plasma progesterone was rarely elevated above 1 ng/ml at any time during the study. Plasma cortisol in the lamb progressively increased from 2 ng/ml prior to days 10-11 prepartum to a level of 60 ng/ml at parturition. Maternal cortisol ranged between 5–25 ng/ml except on the day of delivery when there was an increase to approximately 70 ng/ml. Plasma testosterone in the lamb remained fairly constant around 4 ng/ml until just prior to parturition when it decreased to 1 ng/ml; no consistent fetal sex difference was noted. Maternal testosterone remained low throughout the study period at less than 0.4 ng/ml or approxi...
No takes yet. Share an insight, caveat, or question.
Strott et al. (1974) studied this question.