Published in conjunction with Maternal grandmothers buffer the effects of ethnic discrimination among pregnant Latina mothers by Delaney A. Knorr and Molly M. Fox.

Grandmothers often help the mother-child dyad, but when does this help start? In our lives, we may see many people increase helping behaviors towards a close friend or family member when she has a child to offset her increasing needs. From an evolutionary perspective, these kin and non-kin helpers (or ‘allomothers’) buffer maternal workloads to increase the health and survival of the mother-child dyad. One critical category of allomother that has been studied extensively is grandmothers because of their child-care expertise as well as their often close geographic proximity and emotional connections to the dyad. Much of the research has focused on this allomaternal help at weaning, or more generally, after the child is born. However, given recent evidence that maternal conditions during pregnancy can alter birth outcomes and increase the risk of postnatal morbidities, more evolutionary research is needed to explore prenatal allomaternal effects.

Exposure to stressors during pregnancy is linked to maternal psychological distress, adverse birth outcomes, and increased offspring morbidity and mortality. An evolutionary lens reframes these offspring health issues as a risk to maternal fitness. A prominent stressor relevant to many individuals living in the U.S. is racial/ethnic discrimination (henceforth, discrimination). Given that pregnancy is a vulnerable period for the soon-to-be mother and as-yet unborn offspring, full of social and biological change, we ask in this study if allomothers (particularly soon-to-be grandmothers) buffer stress during pregnancy in order to increase their inclusive fitness. Although the relationships are not typically described this way until after the offspring is born, for clarity we will denote relationships from the perspective of the fetus: maternal and paternal grandmother.  While not all people who become pregnant identify as women or become mothers, we use ‘women’ and ‘maternal’ for clarity of relationships.

Our study uses self-report survey data collected from 216 pregnant women living in Southern California. These women all identified as Latina (a diverse ethnic category), were of various socio-economic backgrounds, and represented the full range of trimesters. While categories of race/ethnicity are not biological, issues related to discrimination has long been recognized for its association with increased psychological distress and physical health. For Latina women living in the U.S., discrimination has been causally implicated in increasing levels of maternal prenatal psychological distress as well as increased odds of low-birth weight. Additionally, Latinas tend to live in three-generation homes more commonly than other groups in the U.S. and tend to share strong cultural values around family, which are both features that make this particular question important to ask in our cohort.  

In this study, we first aim to confirm the expected pattern that prenatal exposure to discrimination increases levels of prenatal psychological distress. We operationalize psychological distress through three separate measures: depression, anxiety, and perceived stress. Second, we aim to determine if grandmother-mother relationship characteristics (particularly, geographic proximity, emotional support, and levels of communication) moderate the relationship between discrimination and psychological distress.

We find a robustly significant, positive correlation between experiencing discrimination and all three measures of psychological distress. Communication with and emotional support from maternal grandmothers buffered this effect. Specifically, greater levels of communication from maternal grandmothers significantly diminished the associations between discrimination and psychological distress (all three measures). Additionally, greater levels of emotional support from maternal grandmothers also diminished the associations between discrimination and depression as well as discrimination and anxiety. We did not observe any significant interactions for paternal grandmother relationship characteristics. Additionally, geographic proximity was not a significant stress-buffer. Results suggest the important role maternal grandmothers play in perinatal mental health, and that these benefits exist uncoupled from geographic proximity.

Since we controlled for the offspring father’s relationship characteristics to the mother, this work supports the importance of allomother help beyond romantic partnerships and the mother-father-offspring family unit. Maternal grandmothers may be a more consistent finding than paternal grandmothers because of stronger effect sizes that are more in range of our statistical power, or perhaps due to stronger bonds of the long-term mother-daughter relationship. This work suggests that maternal grandmothers are likely participating in prenatal stress-buffering activities for mothers; however, our data does not include measures of evolutionary fitness, such as number of children, grandchildren, or offspring survivorship. We make no claim of testing fitness. Future work may connect these prenatal activities to improved birth outcomes and later-in-life fitness outcomes of offspring through longitudinal study designs and the inclusion of infant outcome measures.

Overall, we find that family is a critical component of resilience. This work suggests that encouraging strong social ties to community and extended family is important. While in-person allomaternal care may be critical for instrumental support, these results show that maintaining positive relationships over the phone or internet could also have real and meaningful benefits.

Delaney A. Knorr is a doctoral candidate in the Anthropology Department at University of California, Los Angeles. Her research considers how evolution shapes human pregnancy to be vulnerable to biological and social phenomena. She takes a biocultural approach towards understanding the connections between mothers’ socio-cultural conditions, mental health, and feto-placental development during pregnancy