Jenny Agutter says that becoming a mum at the age of 38 forced her to 'grow up'.
The 62-year-old actress – whose most recent role is as Sister Julienne in Call The Midwife – said that after being single for 15 years she found it difficult to adjust to getting married and having a baby.
But she said the experience was the making of her.
The actress, who is best known for her roles in The Railway Children and Walkabout, told Radio Times: "You grow up when you let someone else into your life in marriage.
"It's a hard adjustment, coming to terms with other people's realities and that you're not going to do everything your way, although it's wonderful to have someone else there."
Jenny, who also has two stepdaughters and is a step-grandmother to two children, aged 11 and eight, was living in Los Angeles when she met Swedish hotelier Johan Tham at a Bath arts festival in 1989.
They married a year later, with their son Jonathan arriving in December 1990.
She said: "In my 20s I felt much more maternal than in my 30s, but there was no one around to have a child with.
"I thought about having one on my own, but knew I wouldn't cope. I needed support.
"I was less broody when I was in a position to have a child, but thrilled when I became pregnant.
"However, they don't tell you that, the moment you're pregnant, your life is taken over. Everything you do, think and feel is affected."
Jenny said she initially cut back on work to look after her new family.
She said: "I didn't want to compromise so that had to take precedence."
But now she thinks there has been something of a renaissance for older actresses.
As the fourth series of Call The Midwife returns to our screens, Jenny said: "There's a more mature audience to be catered for and great stories are being written.
"You no longer have to be young for ever, which is terrific."