One in 5 pregnant individuals report consuming sugar-sweetened beverages at least once per day. Excess sugar consumption during pregnancy is associated with several perinatal complications. As sugar-sweetened beverage taxes become increasingly common public health measures to reduce sugar-sweetened beverage consumption, evidence of the downstream effects of sugar-sweetened beverage taxes on perinatal health remains limited. This longitudinal retrospective study examines whether sugar-sweetened beverage taxes in 5 U.S. cities were associated with decreased risk of perinatal complications, leveraging 2013-2019 U.S. national birth certificate data and a quasi-experimental difference-in-differences approach to estimate changes in perinatal outcomes. Analysis occurred from April 2021 through January 2023. The sample included 5,324,548 pregnant individuals and their live singleton births in the U.S. from 2013 through 2019. Sugar-sweetened beverage taxes were associated with a 41.4% decreased risk of gestational diabetes mellitus (-2.2 percentage points; 95% CI= -4.2, -0.2), a -7.9% reduction in weight-gain-for-gestational-age z-score (-0.2 standard deviations; 95% CI= -0.3, -0.01), and decreased risk of infants born small for gestational age (-4.3 percentage points; 95% CI= -6.5, -2.1). There were heterogeneous effects across subgroups, particularly for weight-gain-for-gestational-age z-score. Sugar-sweetened beverage taxes levied in five U.S. cities were associated with improvements in perinatal health. Sugar-sweetened beverage taxes may be an effective policy instrument for improving health during pregnancy, a critical window during which short-term dietary exposures can have lifelong consequences for the birthing person and child.