Limited data are available for pregnant women affected by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Serological tests are critically important for determining SARS-CoV-2 exposures within both individuals and populations. We validated a SARS-CoV-2 spike receptor binding domain serological test using 834 pre-pandemic samples and 31 samples from COVID-19–recovered donors. We then completed SARS-CoV-2 serological testing of 1293 parturient women at two centers in Philadelphia from 4 April to 3 June 2020. We found 80 of 1293 (6.2%) of parturient women had immunoglobulin G (IgG) and/or IgM SARS-CoV-2–specific antibodies. We found race/ethnicity differences in seroprevalence rates, with higher rates in Black/non-Hispanic and Hispanic/Latino women. Of the 72 seropositive women who also received nasopharyngeal polymerase chain reaction testing during pregnancy, 46 (64%) were positive. Continued serologic surveillance among pregnant women may inform perinatal clinical practices and can potentially be used to estimate exposure to SARS-CoV-2 within the community.