Bouncing on their mother’s lap, little Annabelle and Imogen Weir are the picture of contentment.

Yet this happy, smiling pair faced a battle for survival when they were born at only 23 weeks and four days – making them among the youngest twins ever recorded in Britain.

Annabelle weighed just under a pound. Imogen was just over – and their lives hung in the balance when they came into the world unexpectedly last April.

Imogen Weir was born just 1lb and 1/2oz at 12.58am unexpectedly last April

Spending their first four months in hospital, the identical twin sisters – born three days under the 24-week legal limit for abortion – endured multiple blood transfusions and emergency surgery.

They couldn’t even wear clothes for fear their delicate skin might tear.

However, they are now home in Paisley with their parents James and Claire – and still amazing doctors with their progress.

Mrs Weir, 31, admitted there were times that she felt ‘guilty’ for keeping them alive.

But watching the ten-month-olds grin and kick with excitement at the sight of their favourite cuddly toy, and holding hands when they nap, she knows she made the right choice.

The twins still weigh only 11 and 12lb and have to wear 0-3 month baby clothes.

Annabelle was born 15.5 oz at 12.48am, April 3, 2016 and faced a battle for survival

Mrs Weir – who was also a premature baby, born at 28 weeks – told The Scottish Mail on Sunday: ‘I’d never heard of twins so small surviving. It didn’t seem possible for one, let alone two. I felt really guilty at first. If they didn’t survive, all they would have known was pain.’

She added: ‘They are the youngest and smallest surviving twins to be born in Scotland.

‘The consultant told us that if the girls had been born just two years ago they wouldn’t have survived – that’s how fast medical technology is advancing. They have surprised everyone. They will always be our little miracles.’

Mr and Mrs Weir, who met at university in Dundee nine years ago and married in 2013, were delighted when they found out they were expecting in late 2015 – but hadn’t even considered twins.

Parents James and Claire Weir didn't think their babies Annabelle and Imogen would survive

After some bleeding at seven weeks, Mrs Weir was given an early scan and the couple were told that there were two strong heartbeats.

Town planner Mr Weir said: ‘We don’t have a history of twins as a family, so it was a shock.

We were over the moon and pretty overwhelmed. Claire had to go back for regular scans because she had some other bleeds but each time we were told the babies were OK.’

Mrs Weir’s 20-week scan showed that the twins were growing well – but just a fortnight later, at 22-and-a-half weeks, her waters broke.

I was just trying to keep the babies inside me for as long as possible. It was a really horrible time, filled with worry. I just tried not to move too much – I was even worried to go to the toilet

She said: ‘I went straight to hospital and they admitted me.

'At first it looked like there was still enough fluid for the babies but then they discovered that I was 2cm dilated.

‘I was told the babies could be born soon, which was a huge shock. At that stage it was under the threshold for saving them.’

Doctors at The Royal Alexandria Hospital in Paisley warned the couple that they would not able to provide resuscitation for the infants if they were born under 28 weeks, so Mrs Weir was transferred to the Princess Royal Maternity Hospital in Glasgow.

She said: ‘They said it was up to us what we wanted to do. Some parents of such premature babies decide not to have them resuscitated and instead spend time with them straight after the birth. But we wanted to give our children a chance. We knew we had to try.’

While other mothers on the maternity ward were eager for their babies to arrive, Mrs Weir was desperate to prolong her pregnancy.

Annabelle was born first but has always been the smaller of the two girls

She said: ‘I was just trying to keep the babies inside me for as long as possible. It was a really horrible time, filled with worry. I just tried not to move too much – I was even worried to go to the toilet.

‘After 23 weeks they would at least have a chance of resuscitation so I hoped they would stick in there. I was thinking in days and hours. Each day brought more hope.

‘I got to more than 23 weeks but then I got very ill with a sepsis infection and they had to induce me. The fact that they were twins that I had an infection and they were so premature all lowered their chance of survival. I didn’t have a lot of hope.’

Mr Weir, 31, said: ‘We said goodbye to the girls when they were still inside Claire by reading them a story – Dr Seuss’s Green Eggs and Ham. We thought it might be the only time but we read it to them each night in hospital after they were born.’

In the early hours of April 3 last year, Annabelle was born first, weighing only 15.5oz. Ten minutes later Imogen arrived weighing 1lb and half an ounce.

They were in an ‘extremely fragile state’ but their little hearts were beating.

Mrs Weir said: ‘They were whisked away to intensive care. I had to have an operation because I had a retained placenta and I was ill with sepsis so didn’t get to see them that day.

‘I got to hold Imogen after about six days but Annabelle was smaller and more vulnerable, so I didn’t get to hold her for a few weeks.

‘They were so tiny they fitted in one hand. Annabelle’s foot was about the size of James’s thumbnail. I was petrified when I first held them. They didn’t open their eyes or cry for a few weeks. They couldn’t wear clothes for 100 days, just a nappy and hat. Their skin was too delicate.

‘I felt so helpless. There was nothing I could do to keep them alive, it was up to the machines. The one thing I could do was express breast milk to feed them through a tube in their noses.’

The babies spent six weeks in incubators linked to a hi-tech positive pressure ventilator, which delivers air in gentle ‘breaths’. They also received caffeine to stimulate their breathing.

Imogen is a more ‘rowdy’ and ‘bossy’ than her sister and ‘likes to be heard’ but is also shy

Both of them still receive oxygen through a nasal tube but doctors expect them to come off it soon.

Mr Weir said: ‘Annabelle had stomach issues and used to stop breathing, which was awful. Imogen had to have emergency eye surgery but they have both progressed well.’

Mrs Weir added: ‘We got Imogen home first, a couple of weeks before Annabelle, and it was really tough. I don’t think I slept for about three days. I just watched her constantly to make sure she was breathing. I drove myself almost to distraction.

‘James has been such an amazing husband and father – I couldn’t have done it without him. When Annabelle came home, after 138 days in hospital, we were more prepared.

‘It was a terrifying experience but wonderful to be at home as a family. Now we are experiencing all the normal struggles new parents have but we have loved every minute. We know how lucky we are.

‘It almost feels like the girls are different babies to those born last April. It’s like that period of our lives has been closed and we are moving forward with new hope.

‘For a long time they would lie and look past each other but now they interact and it is just so cute. They will touch hands and try to catch each other’s attention and smile.’

The couple were so grateful for the ‘incredible’ care that they have raised more than £1,700 for the Princess Royal Maternity Baby Fund.

A spokesman for NHS Greater Glasgow and Clyde said: ‘We are delighted to hear Imogen and Annabelle are doing so well.’