There is a video of one of my birthday parties when I was small. In it, amidst the balloons and giddy toddlers one of my friend’s mothers sits crossed-legged on the floor, facing the wall, head down. As a teen, I remember pointing it out to my mum when watching it back and her replying, ‘She wasn’t well when the children were young’. That image embodied postnatal depression for me: a dark cloud of debilitating despair, obvious even to a self-involved teenager.

As the years passed, however, and I had my own children – now nearly seven, four and two – I’ve come to see postnatal depression (PND) in a new light; something that exists on a greyscale, fluctuating between a quiet burden and overwhelming despair.

According to a recent study, one in seven mothers suffer postnatal depression, with up to 20 per cent considering self-harm. The University of Pittsburgh, which screened 10,000 women four to six weeks after giving birth, also found that around one in five of those who screened positive for postnatal depression had bipolar disorder, too.

This condition is as indiscriminate as it is universal. A staggering one in five women will suffer some form of mental-health problem around pregnancy or in the year after giving birth, according to mental-health charity Mind. This ranges from perinatal obsessive compulsive disorder to post-traumatic stress disorder. The most common symptoms of postnatal depression include persistent feelings of sadness, a loss of interest in the wider world, and not bonding with your baby.