Previous research suggests that early life health and resources have long-term implications for a child's health and human capital outcomes. This paper examines whether a generous cash intervention early in life can ``undo'' some of the long-term disadvantage of a low health endowment at birth. To conduct this analysis, we take advantage of new linkages between several large-scale administrative datasets to examine the short-, medium-, and long-term effects of providing low-income families with low birthweight infants support through the Supplemental Security Income (SSI) program. We examine a birthweight cutoff used to determine SSI eligibility at 1200 grams, and find that families of infants born just below this eligibility cutoff experience a large increase in cash benefits totaling about 17% of family income in the first two years of the infant's life. These cash benefits persist at lower amounts throughout childhood for infants whose birthweight falls right below the cutoff. Eligible infants also experience a small but statistically significant increase in Medicaid enrollment during childhood. We examine whether this support affects health care use and mortality in infancy, educational performance in childhood, and adult human capital, earnings, public assistance use, and mortality using data for all infants born in California to low-income families between 1993 and 2019 whose birthweight puts them near the cutoff. Despite the comprehensive nature of this early life intervention, we detect no improvements in any of these outcomes, nor do we find improvements among the siblings of these infants who may have also benefited from the increase in family resources. These null effects persist across several subgroups and alternative model specifications.