Increasingly, babies born in Hong Kong have mainland mothers. According to the Census and Statistics Department, 43 per cent of the 78,822 babies - almost 34,000 - delivered here last year were to mainland mothers. Only about 10 per cent of those mothers had Hong Kong husbands.
Those are incredible figures, considering that in 2001 only 620 babies were born to mainland women here. And the department estimates the numbers will continue to rise, reaching 40,500 this year, 45,500 next year and 49,500 in 2012.
Since Hong Kong women have one of the world's lowest birth rates - well below replacement level - it is good that mainland women are giving birth here, since their children will have the right of abode in Hong Kong.
The trouble, from the government's standpoint, is that there are too many unknowns. It is not known whether and when the babies will return to Hong Kong. One government survey of 11,643 parents suggests that the majority plan to send their children back to Hong Kong between the ages of three and 11.
That means there will be a large pool of school-age children coming to Hong Kong, who will have the right to free education.
Secretary for Education Michael Suen Ming-yeung has said that it is hard to estimate the education demand from these families as the government cannot keep track of them once they leave.
Why not? The government has been aware for years that all children born of mainland mothers have the right of abode here.
This column suggested in 2006 that government officials should interview these mothers and ask them what their plans are and to keep in touch with them after they return to the mainland. After all, it should not be difficult to get their addresses on the mainland, and to send them relevant information periodically, along with questionnaires about when their children will return to the city. It should be made clear to them that their children would be welcome here.
They should be given literature about life in Hong Kong, describing the nursery and kindergarten facilities that are available as well as schooling. Hong Kong offices on the mainland can also keep in touch with them.
If the government had made a greater attempt to keep in touch with these mothers through the years, it would be in a much better situation today to be able to estimate what the numbers of primary and secondary students might be.
Since many of these families do not have relatives in Hong Kong, consideration should be given to setting up boarding schools.
The expectation now is that, soon, mainland mothers will account for half of all babies born here.
From Hong Kong's standpoint, the earlier these children make their homes here, the better. They will have an opportunity to get a Hong Kong education and absorb Hong Kong values and become no different from other Hong Kong people. But if they do not come here until they are adults, they will be arriving like immigrants who have a different set of values.
Of course, many of them may go to international schools on the mainland and get an above-average education. But it would certainly be better if they have a chance to become integrated into the Hong Kong community at an early age.
Otherwise, there will be a danger that Hong Kong will be divided into two communities, one of locals and the other of mainlanders who, while they have the right of abode, are little different from other mainlanders.
It is a situation that can be avoided and we should be doing all we can now to prevent that from happening.
Frank Ching is a Hong Kong-based writer and commentator. firstname.lastname@example.org