Womb to womb: Maternal litter size and birth weight but not adult characteristics predict early neonatal death of offspring in the common marmoset monkey

Abstract

A singular focus on maternal health at the time of a pregnancy leaves much about perinatal mortality unexplained, especially when there is growing evidence for maternal early life effects. Further, lumping stillbirth and early neonatal death into a single category of perinatal mortality may obscure different causes and thus different avenues of screening and prevention. The common marmoset monkey (Callithrix jacchus), a litter-bearing nonhuman primate, is an ideal species in which to study the independent effects of a mother’s early life and adult phenotypes on pregnancy outcomes. We tested two hypotheses in 59 marmoset pregnancies at the Southwest National Primate Research Center and the Barshop Institute for Longevity and Aging Studies. We explored 1) whether pregnancy outcomes were predicted independently by maternal adult weight versus maternal litter size and birth weight, and 2) whether stillbirth and early neonatal death were differentially predicted by maternal variables. No maternal characteristics predicted stillbirth and no maternal adult characteristics predicted early neonatal death. In univariate Poisson models, triplet-born females had a significantly increased rate of early neonatal death (IRR[se] = 3.00[1.29], p = 0.011), while higher birth weight females had a decreased rate (IRR[se] = 0.89[0.05], p = 0.039). In multivariate Poisson models, maternal litter size remained an independent predictor, explaining 13% of the variance in early neonatal death. We found that the later in the first week those neonates died, the more weight they lost. Together these findings suggest that triplet-born and low birth weight females have distinct developmental trajectories underlying greater rates of infant loss, losses that we suggest may be attributable to developmental disruption of infant feeding and carrying. Our findings of early life contributions to adult pregnancy outcomes in the common marmoset disrupt mother-blaming narratives of pregnancy outcomes in humans. These narratives hold that the pregnant person is solely responsible for pregnancy outcomes and the health of their children, independent of socioecological factors, a moralistic framing that has shaped clinical pregnancy management. It is necessary to differentiate temporal trajectories and causes of perinatal loss and view them as embedded in external processes to develop screening, diagnostic, and treatment tools that consider the full arc of a mother’s lived experience, from womb to womb and beyond.

Linking personality traits and reproductive success in common marmoset (Callithrix jacchus)

“…Hence, we could not study the age-dependent effects of personality on reproductive success. Furthermore, other variables could have affected reproductive performance but were not available in our data, such as maternal litter size, parental body and health condition, parental endocrine parameters, initial condition of infants, and the number of helpers at each litter 35 , 36 , 39 , 63 , 64 . Recent studies also indicate the importance of infant-parent personality interactions 25 , a promising area for future studies.…”

Differences in nutritional status between rural and urban Yucatec Maya children: The importance of early life conditions

“…Early‐life conditions and exposures shape childhood growth, vary over space and time, and are affected by urbanization and the nutritional transition. Evidence from human and animal models show that adverse environmental influences during sensitive periods of early development can have significant and negative consequences for growth and health in both the short and long‐term (Barker, 1993; Gluckman et al, 2006; Martorell, 2017; Matthews et al, 2017; Rutherford et al, 2021). In humans, this is particularly true from conception to the end of the second year of life (“the first 1000 days,” http://thousanddays.org/)),which represents a critical period for brain and body growth and immunologic and metabolic maturation (Cusick & Georgieff, 2016; Mayneris‐Perxachs & Swann, 2019; Robertson et al, 2019; Wells et al, 2020).…”