Abstract
Abstract
Mice selected for large litters were used to study the relationship between fetal number and maternal progesterone and testosterone concentration. Experimental adjustment of conceptus number demonstrated that the presence of one fetus was sufficient to elevate maternal progesterone concentration above that found in females from which all conceptuses were removed. When one of more fetuses occupied the uterus, maternal progesterone concentration did not increase with increasing conceptus number. In contrast, maternal testosterone concentration was positively correlated with the number of fetal-placental units.
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