Effects of superovulation on fetal development and hormone levels in the pregnant hamster.

Treatment of hamsters with 30 i.u. PMSG induced ovulation of 46 ova/animal, 90% of which were fertilized. CL growth was normal. About 27 zygotes/animal implanted and at term (Day 16) the litter size of the PMSG-treated hamsters was 21 compared to the normal number of 10. Parturition occurred at the normal time. Average weight at birth was about 500 mg less for young of PMSG-treated mothers than for controls. Differences were found in the serum progesterone and oestradiol concentrations of the treated and control hamsters, but serum FSH and LH levels were similar.