Litter Size, Maternal Parameters, and Brain and Body Parameters of Neonatal Rats

Abstract

The present work is concerned with the effect of natural litter size in the rat on the brain and body parameters of individual newborns, with particular reference to those newborns that were ‘outstanding’ (i.e., had parameters higher than mean ± 2 SD). Correlations between litter size on one side, and length of gestation, number of stillborns, maternal weight at conception and maternal food consumption were also studied. To our knowledge, no previous report presented a similar integrated study on such a large number of rats (288 litters, 2,725 newborns) and wide range of litter size (2–17).

Analysis of Historical Control Litter Parameters of Reproduction Toxicity Studies in Sprague-Dawley Derived Rats

“…The high fetal weight of Fla fetuses in Seg. II was an inverse effect of the smaller litter size [8] . Historically, a high fetal weight occurred in 1974 followed by a trough in 1976, but during recent years, the fetal weight gradually increased independent of study design and generation.…”