Motherhood was never in my plans. I was an only child with no instinct to coo over the babies friends had – they looked far too much work for no payback. Then, in my late thirties, an ‘I-want-a-baby’ switch went on inside me. I was pregnant a month after my husband and I decided to have a family, and a month before our marriage started to fall apart. As well as all the many changes happening to my body the fact that my life would never be the same again hit me like a ton of bricks.

‘What have I done?’ I thought, leaning over the toilet bowl for the umpteeth time (morning sickness, hit me at every time of the day but the morning). But I was lucky in that two of my best friends had also fallen pregnant at exactly the same time, so I had companions on that nine-month journey. Sadly, I knew the likelihood was that I would end up being a single parent, which drew me even closer to ‘the blob’. I poured everything into a diary: fears, hopes, recorded everything happening both within me and outside me.

At the first scan, I fell in love with this little thing growing inside me with a ferocity I wasn’t prepared for. I embraced pregnancy with all its aches and pains and inconveniences and the wonderful new wardrobe of loose-fitting dresses and trousers and found friendship with women in my parentcraft class – all of us with so much in common despite our different ages, backgrounds and circumstances. I remember so much love in that time – none of it from the quarter where it should have come from most – but it didn’t matter because friendship was everywhere, warm and accepting and caring.

My son arrived in a blaze of drama almost killing us both and I was consumed with a tsunami of love when he was handed to me in all his indignant glory. And months later, whilst sitting in my front room with my two besties and their babies sharing tales of how our drug-filled births differed from our holy no-drug birth-plans, there was a wondrous epiphany: Write about this, this new world you have become part of. A world of motherhood, babies and the strength of friendship.

For years I had struggled to find the right thing to write about to secure me that elusive book deal - my one big dream - and here it was parading openly in front of me. Aided by that pregnancy diary, I started to pen the story that was to put me on the path to writing success at last: a tale of three friends all falling pregnant at the same time.

Motherhood has increased my life by another dimension and made me stronger for it and yet softer too. It has given me the biggest joys of all… and the writing career I dreamed of. Whatever pressed that switch twenty-one years ago changed me, saved me, made me.

The Magnificent Mrs Mayhew is out now, published by Simon & Schuster, priced £14.99 in hardback.