Objective <p>To investigate the impact of COVID-19 infection on maternal and neonatal outcomes and immunity in pregnant women in China.</p> Methods <p>283 pregnant women with COVID-19 were included in the prospective observational cohort study and divided into five groups based on infection stage. Antibody levels were measured in plasma, umbilical cord blood, and breast milk, and combined with clinical data and 6-month follow-up results. We measured SARS-CoV-2 antibody levels using a chemiluminescence immunoassay and analyzed the data with the Kruskal-Wallis test, χ2 test, or Fisher’s exact test.</p> Results <p>No significant differences were found in age, BMI, weight change during pregnancy, or the incidence of gestational hypertension, gestational diabetes, gestational hypothyroidism, intrahepatic cholestasis, transaminitis, preterm birth, small for gestational age, neonatal NICU transfers, developmental delays, and hearing damage among the five groups. The incidence of COVID-19 in infants from mothers infected at different stages of pregnancy was significantly lower than in the uninfected group (<i>P</i> &lt; 0.05). Maternal and umbilical cord blood showed significantly higher IgG levels in the infected group compared to the uninfected group at different stages of pregnancy (<i>P</i> &lt; 0.05). The median transplacental antibody transfer ratio across all infection groups was 1.15 (0.98–1.30), with no significant differences between them. The reinfection group had significantly higher IgA levels during pregnancy compared to other groups (<i>P</i> &lt; 0.05).</p> Conclusion <p>No adverse outcomes were observed in mothers or infants at any stage of maternal SARS-CoV-2 infection. Antibodies in umbilical cord blood and breast milk may offer passive immunity to newborns for 1–3 months. Reinfection during pregnancy may extend this immunity without raising the risk of adverse outcomes.</p>