Matrilineal transmission of birth weight in the rhesus monkey (Macaca mulatta) across several generations.

OBJECTIVE: To investigate how secular trends in maternal weight characteristics, in response to living in a permissive laboratory environment, influence intergenerational trends in birth weight in the rhesus monkey (Macaca mulatta) and to assess the role of female offspring in perpetuating these matrilineal traits.
METHODS: A multigenerational data set was used to evaluate the relationship between familial and contemporaneous pregnancy factors and infant birth weight across several generations. These records provided 25 years of information on the maternal and paternal ancestries and reproductive histories, gestation lengths, and birth weights for 1321 infants.
RESULTS: Pregnancy weight gain, gestation length, and maternal familial factors were the most important predictors of infant birth weight, followed by infant sex, paternity, and maternal pregravid weight (P<.001 for each variable). Furthermore, the trend in fetal growth across generations followed a matrilineal pattern of transmission that was much more pronounced for female than male offspring (P<.001). Although secular increases in maternal pregravid weight and pregnancy weight gain were detected, the upward shift in female birth weight was not explained solely by these changes in maternal weight parameters.
CONCLUSION: With the delivery of ample nutrition and health care in a laboratory setting, there was a dramatic increase in the birth weight of daughters within certain matrilines, providing evidence that an intrauterine mechanism transmitted through female progeny can regulate fetal development. Further, the upward trend in female birth weight had a beneficial influence on the reproductive performance of female descendants in those lineages.