HOSPITAL services for very ill babies are to move from Huddersfield to Halifax.
The neo-natal intensive care unit at the Royal Infirmary is having to shut for part of the summer because of a shortage of doctors.
Emergency admissions of children to the Infirmary during the night will also be suspended.
But accident and emergency services are unaffected.
The children's services are being switched to the Calderdale Royal Hospital.
Health chiefs say they had to bring in the temporary closures because of concern over new laws on doctors' hours.
The health chiefs say they cannot get skilled doctors for the HRI units.
But they could not say when the neo-natal unit or the night-time admissions service may be restored in Huddersfield.
The shutdown starts on August 1.
A spokesman for the Calderdale and Huddersfield NHS Trust said: "We had no choice but to temporarily move some of the children's services to one site, in order to meet the new legislation governing the working hours of doctors in training.
"In order to comply with the European Working Time Directive the trust is recruiting a number of doctors.
"Unfortunately, these staff will not all be in place by August 1. So we are making temporary arrangements to ensure we comply with the legislation while still offering a safe and effective service to our patients."
All neo-natal intensive care services will be based in Halifax.
The neo-natal unit specialises in care for very ill babies and babies born prematurely, perhaps as early as 28 weeks.
It is staffed continuously.
The special care baby units, which offers extra help for babies, will remain on both sites.
The trust spokesman added: "The paediatric assessment unit at the Royal Infirmary will continue to be provided and the paediatric ward will remain open 24 hours a day.
"Any emergency referrals of children after 7pm who need admitting to hospital will be transferred to the Calderdale Royal during this time.
"We estimate that these temporary changes will affect about three patients a week.
"The trust has been working towards complying with the European directive for a number of months. Failure to comply with it could result in prosecution for the trust."
The spokesman said there was a national shortage of skilled doctors for paediatric care.
Gail Button's son, Thomas, was in the Royal Infirmary for two months after he was born 10 weeks early.
Gail, 29, of Golcar, and partner Steven Sutcliffe visited Thomas daily.
He was very poorly - but he's now a strapping, healthy three-year-old.
Gail said: "The idea of any such services going to Halifax is terrible.
"When your baby is in hospital it's stressful enough - without having to get to the next town to see him.
"The infirmary has a great set-up and the staff are so superb. We need to make sure we hang on to our services," she added.