By Branwen Jeffreys BBC News Reporter

He was born prematurely at 32 weeks, and has only just been allowed home.

It's the second time his mother Kerri has gone through an early birth.

Four years ago her daughter Katie was also born prematurely - an experience Kerri found frightening and distressing.

Premature babies: Vital days

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She was given medication to delay labour. Even an extra day or two in the womb can make a difference to the survival and development of a premature baby.

But with each dose of the drugs Kerri experienced side-effects such as powerful heart palpitations.

She told the BBC: "It was very frightening. They had to stop the drug and I went into labour.

"It's frightening enough being in labour without knowing you're having a baby at 32 weeks and not knowing what�s going to happen afterwards."

Her experience isn't unusual and Kerri's symptoms are typical of a type of drugs commonly used to delay labour called beta agonists.

They're known to have unpleasant side-effects. Mothers needing to delay premature labour have put up with the risks for the sake of their babies.

'Cheap, nasty drugs'

Ronald Lamont is one of the doctors who believe that should no longer be the case.

He is a consultant obstetrician at Northwick Park Hospital, which took part in trials of an alternative.

He argues that some women are still being offered what he calls "cheap and nasty" drugs.

A large-scale international trial has compared the beta agonists still used in many UK hospitals with an alternative called Atosiban.

It found Atosiban to be at least as effective in delaying premature labour.

If there's any treatment that is more effective and safer we would hope it can be used widely

Bonny Green Charity Bliss

And importantly the side-effects for mothers are significantly less.

He said: "They don't have a fraction of the side-effects the other agents have.

"In terms of efficacy - the ability to stop pre-term labour and prolong gestation - they're as good as if not better than existing drugs."

New guidelines on the use of drugs in delaying labour are expected later this year from the Royal College of Obstetricians and Gynaecologists, but it is not yet known whether they will recommend the newer drug.

Bonny Green, from the premature baby charity Bliss, said: "We're very concerned that if a mother is having a premature baby the birth should be delayed.

"If there's any treatment that is more effective and safer we would hope it can be used widely."