At 18 months Ellie, Georgina, Jessica and Holly Carles, who arrived against odds of 64 million to one, have left their health problems behind.
And in jeans and t-shirts the only identical quadruplets in the country are ready to toddle out and explore the big, wide world.
Their mother, Julie, 39, said yesterday: “It’s amazing to think they have come this far and they are walking by themselves. I look at them and I think it’s just wonderful.
“I always wonder how are they going to learn to talk or ride a bike. But they surprise me every day.”
When Mrs Carles, a former manager at a building firm, became pregnant – without fertility treatment – she was determined to carry all the children despite the risks.
And when the girls were born last March, they were so tiny that the smallest, Jessica, weighed 1lb 9oz.
After a time in hospital incubators, the girls have thrived – even though they are still small for their age and wear clothes designed for babies aged nine to 12 months.
Mrs Carles, who lives near Biggleswade, Bedfordshire said: “Now that they are walking they are into everything and anything and I have to have eyes in the back of my head.”
Her 34-year-old husband, Jose, said: “We wouldn’t be without them for the world.”