Physical and behavioral sequelae of low birthweight in spiny mice (Acomys cahirinus).

Physical and behavioral sequelae of low birthweight (LBW) were investigated in spiny mice (Acomys cahirinus). When raised by their biological mother, pups whose Day-2 weights were 1 SD or more below the population mean remained smaller through the first 30 days postpartum than pups born within normal (N) weight ranges. LBW pups fostered onto mothers who gave birth to N pups gained weight more rapidly than LBW pups remaining with their own mother. Similarly, N pups fostered onto mothers of LBW pups displayed reduced weight gain relative to N siblings raised by their biological mother. It appears that rate of weight gain is influenced by an interaction between birthweight and maternal rearing environment. LBW pups also were less responsive than N pups to maternal chemical cues, indicating that low birthweight is correlated with deficits in adaptive behavior.