Postnatal depression

Jilly • I first joined glow to track my periods and ovulation, now I'm here tracking the progress of my first pregnancy. Jan17
Has anyone else been told that they are at higher risk for postnatal depression/have any other mums experienced it? 
They were really just basing it off answers I have to a brief questionarre, so not much for them to go off, but the midwives and my partner want me to continue seeing a social worker throughout pregnancy and likely afterwards too. 
I do have a history of depression and anxiety - but for the most part of the past eighteen months I have been very happy and really enjoying life. I know having a baby should add to that joy, but now I'm worried about getting stuck in another hole I may struggle to get myself out of.