Super pregnancy in a BALB/c mouse superovulated with PMSG

This paper reports a case of super pregnancy in a BALB/c mouse pregnant with 30 pups following induction of superovulation using a PMSG-hCG protocol. Superovulation was induced in 10 mice by injecting 5 IU PMSG followed by 5 IU hCG 48 hours later. Immediately after injection of hCG, animals were placed with males at a ratio of 1 to 1 for 24 hours. On day 14 after mating, animals were killed by cervical dislocation and the uterus was examined for pregnancy and the number of fetuses. The mean (±SEM) number of fetuses observed in ten mice was 5.4±3.18 with an unexpectedly super pregnant mouse bearing 30 fetuses on day 14 of pregnancy.