UNDERWATER births have been barred at Matilda hospital on the Peak despite the introduction of Southeast Asia's first birthing tub. Demands for a full safety inquiry into birthing pools have escalated in Britain since doctors reported that three babies had died in the past four years following water births, taking the number of deaths associated with the technique to five. But such tragedies would not be repeated in Hong Kong because the pool would be used only in the early stages of labour, said the Matilda's medical superintendent, Dr Tim Dawbarn. ''Underwater deliveries can be dangerous and some mothers have been anxious about using the pool, but there is no problem with sitting in it to ease labour pains and then getting out to give birth normally,'' he said. ''We have been very cautious and conservative about installing this pool but we have come under increasing pressure from patients who are keen to give birth as naturally as possible. ''The most important thing is to have healthy babies and mothers and we will ensure that the use of the pool to relieve pain during labour is perfectly safe.'' The new birthing tub - or pain-relief pool - cost about $15,000 to install and will cost each patient about $2,500 to use on top of normal delivery charges. Dr Dawbarn said: ''We have been using warm baths to relieve labour pain for some time and we saw the pool as a better way of doing this. So far, mothers have been delighted with the benefits.'' The hospital is the first in the region to install the specially-designed tub. It has already helped to ease the labour pains of two women who chose to take the plunge and there is confidence that the technique will catch on. Dr Dawbarn said: ''At the moment, birthing tubs are seen as being a bit trendy and I think Hong Kong mothers will be cautious at first. But in time I think they will be accepted as just another option in pain relief.'' A spokesman for the Hospital Authority said there were no plans to instal a birthing tub at a public hospital because there had been no demand for one.