Energy restriction initiated at different gestational ages has varying effects on maternal weight gain and pregnancy outcome in common marmoset monkeys (Callithrix jacchus)

With relatively high fertility and short lifespan, marmoset monkeys (Callithrix jacchus) may become useful primate models of prenatal nutritional effects on birth condition and adult disease risk. The present study determined the effects of energy restriction to 75 % of expected ad libitum consumption during mid- (day 66) or late (day 99) gestation on maternal weight, fetal growth and pregnancy outcomes in this species. Mid-restriction reliably induced the loss of pregnancy before term, at 92 d, on average. Of the late-restricted pregnancies, four of seven were normal term length while three were preterm deliveries, at 101, 117 and 132 d. Control females had a mean mid-pregnancy weight gain of 0.67 g/d while mid-restricted females lost -0.65 g/d, on average. Control pregnancies averaged a 1.06 g/d gain during late pregnancy, while energy-restricted females lost -0.67 g/d, on average. Restriction-related weight change was highly variable, ranging from +0.55 to -2.56 g/d for mid-restriction pregnancies and from +0.79 to -3.91 g/d for late-restriction pregnancies. For mid-restriction pregnancies, the number of restriction days was best explained by linear weight change and total weight loss while the number of restriction days in late pregnancy was best explained by linear weight change alone. In late-restriction pregnancies, smaller females had higher daily weight losses. Restrictions did not induce litter-size reduction or growth restriction in those infants that were delivered at term but the size of aborted fetuses suggested that at least some pregnancies lost preterm may have involved impaired intra-uterine growth.