The 38-year-old former Spice Girl feared falling pregnant with three-year-old daughter Scarlet would reignite her illness - but was surprised to find it got rid of it completely.
She said: "If you`ve had depression in the past, you`re more prone to it again.
"But if anything, being pregnant and having a baby gave me a fresh start.
"My health visitor checked in on a regular basis as she was aware of my history of depression. My mum was also a fantastic help and she travelled down to London from Liverpool every weekend for the first few months.
"I believe their support helped keep my depression at bay. I have never felt better and I haven`t had any gloomy thoughts in years.
"Having Scarlet has given me the confidence to say I`m totally cured of any depression and I can`t tell you how great that makes me feel."
Mel believes her dark spell - which led to 18 months of anti-depressants, counselling and alternative therapy - was sparked by an eating disorder she developed whilst in the Spice Girls.
In an interview with the Daily Mirror, she explained: "The stress of suddenly being thrust into the limelight led me into an unhealthy relationship with food and exercise.
"I became obsessed about what I ate and I cut lots of food groups, like carbs and protein, out of my diet. I survived on fruit and vegetables and little else.
"Surviving on a few hours of sleep while on tour, not eating properly and depriving my body of essential nutrients sent me into this awful depression.
"After years of living on adrenaline, my body was so out of balance I came crashing down." But now weighing in at a healthy 133lbs, she credits pregnancy with finally helping her overcome her food hang-ups.
She said: "I had to be healthy and from the moment I knew I was pregnant, I wanted to give Scarlet the nutrition she needed to grow fit, strong and healthy.
"I started to feel so comfortable around food that I went out for lots of lunches and I had a pudding every time.
"I put on about three-and-a-half stone (49lbs) throughout my pregnancy but I didn`t really worry. I found it liberating. I breastfed for seven months so I made sure that I ate enough food and didn`t exercise too much.
"The weight started to come off slowly but I was determined not to get stressed about it."