ObjectiveTo describe the mental health of perinatal women in five European countries during the third pandemic wave and identify risk factors related to depressive and anxiety symptoms.DesignA cross-sectional, online survey-based study.SettingBelgium, Norway, Switzerland, the Netherlands and the UK, 10 June 2021–22 August 2021.ParticipantsPregnant and up to 3 months postpartum women, older than 18 years of age.Primary outcome measureThe Edinburgh Depression Scale (EDS) and the Generalised Anxiety Disorder scale (GAD-7) were used to assess mental health status. Univariate and multivariate generalised linear models were performed to identify factors associated with poor mental health.Results5210 women participated (including 3411 pregnant and 1799 postpartum women). The prevalence of major depressive symptoms (EDS ≥13) was 16.1% in the pregnancy group and 17.0% in the postpartum . Moderate to severe generalised anxiety symptoms (GAD ≥10) were found among 17.3% of the pregnant and 17.7% of the postpartum women. Risk factors associated with poor mental health included having a pre-existing mental illness, a chronic somatic illness, having had COVID-19 or its symptoms, smoking, unplanned pregnancy and country of residence. Among COVID-19 restrictive measures specific to perinatal care, pregnant and postpartum women were most anxious about not having their partner present at the time of delivery, that their partner had to leave the hospital early and to be separated from their newborn after the delivery.ConclusionApproximately one in six pregnant or postpartum women reported major depression or anxiety symptoms during the third wave of the pandemic. These findings suggest a continued need to monitor depression and anxiety in pregnancy and postpartum populations throughout and in the wake of the pandemic. Tailored support and counselling are essential to reduce the burden of the pandemic on perinatal and infant mental health.