The purpose of this pilot study is to test the feasibility of an online 10-Week group cognitive behavioural therapy (CBT; a type of talking therapy) intervention for postpartum depression and anxiety that is led by psychotherapists, social workers, a psychologist and/or a psychiatrist. Mothers and birthing parents who are 18 years or older, have an infant under 12 months, living in Ontario and who have postpartum depression and/or anxiety symptoms will be assigned with a 50/50 chance (like flipping a coin) to receive online transdiagnostic group CBT in addition to usual postnatal care, or to receive usual postnatal care only.