PROJECT SUMMARY Women in South Asia often return to their natal homes in different communities during pregnancy, for childbirth, and postpartum. Our team conducted the first robust measurement of this phenomenon in two states of India (coining the term “temporary childbirth migration (TCM)”) and found that about one-third of women returned to the natal home point during the perinatal period. Given India’s reliance on community-based maternal and child health care delivery, TCM may disrupt care continuity, negatively impacting health care access and health outcomes. Conversely, given the lower status of women in their marital homes, TCM could potentially improve health outcomes for migrants, leaving those “left behind” at higher health risk. A greater understanding of TCM, its impact, and associated mechanisms are critical inputs to inform policy and practice to improve maternal and neonatal health in India. However, despite anecdotal evidence of TCM’s widespread prevalence across diverse Indian contexts and its potential impact on health, it is not well defined or quantified in the literature. The objective of this study is to characterize TCM in India, describe its impact on perinatal outcomes, and explore the health care continuity and social support as potential mediators of these relationships. First, we will collect cross- sectional data from roughly 6000 women at eight Health and Demographic Surveillance Sites throughout India to define and characterize temporary childbirth migration, including magnitude, timing, drivers, and sociodemographic and geographic heterogeneity. Triadic qualitative interviews with household members in 2 sites will shed additional light on selection and drivers of TCM. Then, we will select three sites based on geographical distribution and differing levels of TCM for a longitudinal study. We will recruit 1000 women in each site (3000 total) who are early in pregnancy and follow them until one year postpartum, some of whom will migrate and some not. We will collect monthly telephone surveys and five longer in-depth surveys from women about migration patterns, health care use, maternal and child health outcomes, social support, and socio- demographics. We will ask women to take photographs on their mobile phones (provided to those without phones) of health record data to have higher quality maternal and infant outcome data. We will estimate the impact of TCM on preterm birth and identify women most at risk. We will then examine disruptions in the continuum of perinatal care and social support as potential mediators between temporary childbirth migration and health. These findings will help us understand factors that may be contributing to poor maternal and child health outcomes in India, and potentially other parts of South Asia and other regions. A better understanding of the impact of TCM can help programs and policies better support women to obtain the care and support they need in pregnancy and postpartum.