
Immigration officers at the border were under orders to stop any woman more than seven months pregnant and refuse them entry to the territory unless they had a hospital appointment.
By mid-day there were no figures available for the number of women who had been turned away, although television pictures showed some being questioned.
A government spokesman said a tally would be issued later in the day.
The new rules were introduced to help plug a hole of 322 million Hong Kong dollars (41.3 million US) in hospital coffers, incurred mostly by mainland mothers leaving maternity wards without paying their bills.It would also allow hospital chiefs to give priority to local residents following complaints that vital resources were being taken up by non-residents.
Under the new rules, Chinese mums-to-be who are allowed through will have to pay higher fees -- up from 20,000 dollars to 39,000 dollars -- for deliveries.
Chinese mothers have been flooding into Hong Kong to have their babies because services are of a higher standard than they could get at home.
Further, babies born here to at least one parent of Chinese origin are automatically granted Hong Kong citizenship, seen as a way for children to enjoy the territory's medical, social welfare and education advantages.
The number of women from mainland China who gave birth here has grown from 3,600 in 2004 to 8,800 in 2005. The figure then surged to 11,716 in the first half of 2006, overwhelming hospitals.
A government spokesman said the measures applied to all non-residents, but were principally aimed at deterring pregnant women from the mainland seeking last-minute admissions to hospital emergency wards for deliveries.