Introduction During the COVID-19 pandemic, stress and anxiety in the population increased due to concerns about people's own health and that of their relatives, as well as changes in everyday life due to measures taken to reduce the infection rate. Pregnant women are particularly stressed. The present study examines how the COVID-19 pandemic affects the stress experience and mental health of pregnant women and mothers of newborns and how care could be optimized. Methods As part of the international COVGEN initiative ( https://www.covgen.org ) to investigate the effects of the COVID-19 pandemic on the peripartum period, pregnant and postpartum women were asked about their experience with stress using the COPE-IS (Coronavirus Perinatal Experiences - Impact Survey) questionnaire developed for this purpose and translated from the English. In addition, demographic data, pre-existing diseases, pregnancy complications and the care situation were recorded. The questionnaire was either administered as hardcopy to inpatients at the Department of Women's Health, University Hospital Tübingen, Germany, or online. All pregnant women and mothers who were pregnant or had given birth after the official start of the COVID-19 pandemic (11 March 2020) were eligible to participate. Results Complete data sets of n = 156 pregnant women and n = 221 postpartum women were available for evaluation. The general stress level assessed with the COPE-IS was significantly increased by the COVID-19 pandemic in both, pregnant and postpartum women, with pre-existing conditions such as respiratory diseases and pregnancy-related diseases like gestational diabetes adding to the stress. The subjectively perceived quality of care/support during pregnancy also influenced the stress level. Conclusions Fears of a COVID-19 infection and changes in preventive and aftercare services were a burden for the women surveyed. Intensified care during pregnancy and puerperium could help to stabilize the mental situation and reduce stress.