Postnatal depression can affect women in different ways. It can start at any point in the first year after giving birth and may develop suddenly or gradually.
Many women feel a bit down, tearful or anxious in the first week after giving birth. This is often called the “baby blues” and is so common that it’s considered normal. The “baby blues” don’t last for more than 2 weeks after giving birth.
If your symptoms last longer or start later, you could have postnatal depression.
Link to information on post natal depression
https://www.nhs.uk/conditions/post-natal-depression/symptoms/