Pregnancy in Mice Selected For Small Litter Size: Reproductive Hormone Levels and Effect of Exogenous Hormones

Abstract

Concentrations of mouse plasma LH, FSH, prolactin (PRL) and progesterone were measured throughout pregnancy in a small litter size line (CN—) in which prenatal mortality is markedly increased especially at the postimplantation stage. The pattern and magnitude of LH and PRL concentrations in line CN— were not significantly different from those previously reported in a control line (C). Levels of FSH and progesterone, however, were lower in the CN— than in line C during the second half of pregnancy. Gonadotropin administration from days 6 through 12 was ineffective in reducing prenatal losses in line CN—, whereas progesterone treatment reduced fetal losses to the level found in line C.