•Lack data on support and quality of life in pregnant women affected by COVID-19.•Parents-in-law and relatives’ support was related to a high QOL of this population.•Emotional and appraisal supports had major roles in changing QOL of pregnant women. This study explored the associations between different structural and functional supports with the quality of life (QOL) and mental well-being of pregnant women whose antenatal care was delayed due to the COVID-19 pandemic in Vietnam. A multi-center cross-sectional study was performed on 868 pregnant women. The pregnant women's quality of life questionnaire (QOL-GRAV), the Edinburgh Postnatal Depression Scale (EPDS), and the Perinatal Infant Care Social Support (PICSS) instruments were employed. The satisfaction with care from different sources was measured. Multivariate Tobit Regression models were used. Seventy pregnant women (8.1%) reported that their antenatal care was influenced by the COVID-19. In this group, a higher level of satisfaction with the care of parents-in-law and a higher score of emotional support were associated with a better “Physical and Emotional changes” domain, while a higher level of appraisal support was related to poorer “Physical and Emotional changes” domain. A higher level of satisfaction with relatives’ care and a higher score of emotional support were correlated with a better “Life Satisfaction” domain. EPDS score was negatively correlated with satisfaction with parents-in-law care and appraisal support. Our study highlighted that intervention programs to improve the QOL and psychological well-being of pregnant women in epidemics such as COVID-19 or other diseases in the future should involve other family members such as parents-in-law and relatives as sources of support. The cross-sectional design was unable to draw causal relationships. Recall bias might occur. The convenient sampling method might limit the generalizability of findings.