Participant inclusion and exclusion criteria
| Inclusion criteria | Exclusion criteria |
| Women who are 18 years old or older | Current diagnosis of depression or other mood disorder made by a health professional |
| Up to 14 weeks pregnant (assessed through a dating ultrasound scan) | Currently receiving treatment for depression or other mood disorder (whether it is talking therapies or pharmacological treatment) |
| Any parity | Recent personal history of depression or other mood disorder in the past 12 months |
| Attending antenatal clinics in participating National Health Service sites | Not comfortable reading and writing in English |
| Own smartphone (either an iPhone or any type of Android handset) | Not owning a smartphone, or owning an incompatible handset (ie, Windows Phone, Blackberry or Linux) |