Effects of stage of gestation and litter size on prenatal growth in the mouse

Abstract

SUMMARYA theoretical equation is proposed which describes the dynamics of foetal growth in mice. The equation is basically of exponential form and takes into account the effects of stage of gestation (T) and number of foetuses (N) on the instantaneous relative growth rate. The model was tested against experimental data by using a stepwise regression technique. Both stage of gestation and number of foetuses had significant effects (P< 0·01) on the instantaneous growth rate. When the model was tested against another set of data 44 out of a total of 52 comparisons had a prediction error less than 15 %. As a result, the following equation is proposed to describe the foetal growth of miceW = e-14·34Ne(1·302–0·0276T–0·00059)TAn equation of this form could be useful in interpreting prenatal growth data for other species. Other factors which may influence the dynamics of foetal growth, such as maternal age or weight, could also be incorporated into the equation.