Such are the trials of Hong Kong’s latest baby boom–one with a cross-border twist. Over the past two years so many mainland women have flocked into the territory to give birth in the city’s public hospitals that Hong Kong maternity wards now resemble emergency rooms. Deliveries to what the Hospital Authority deems “noneligible” persons now constitute roughly one third of total births in public hospitals, a figure that’s expected to surpass 20,000 in the fiscal year ending in March.

Why are so many coming? Some women seek to avail themselves of Hong Kong’s superior medical care or dodge China’s strict family-planning rules, to be sure. But the majority seek something they believe will give their newborns a leg up in life: Hong Kong citizenship. “It’s just like in the old days when Hong Kong people would go to Canada or the U.S. to have their babies,” quips one senior civil servant. “Only now we’re at the receiving end.”

The influx is a demographic blessing, of sorts. Hong Kong has one of the world’s lowest birthrates and faces a serious aging crisis, so much so that Chief Executive Donald Tsang has called on young married couples to adopt a “three-child policy” to boost the city’s paltry fertility rate. But many in Hong Kong worry that care for local women could be compromised in the rush. And the notion of tourists’ plotting to gain passports for their unborn babies strikes a discordant note. Residents foresee large numbers of newcomers demanding free schooling and social services and low-cost medical care. “Hong Kong is faced with an uncontrollable number of mainland babies,” warned the Savantas Policy Institute, a think tank, last month. “There is no way of predicting or controlling the number of such children, or the timing of their subsequent re-entry.”

Top officials have voiced concerns with Chinese leaders–and in late December the city’s Hospital Authority unveiled new measures, to be enacted within weeks, to slow the influx and to bolster obstetric services. They include doubling maternity fees charged non-Hong Kong patients to $5,000, pay raises to help recruit more midwives and efforts to ensure that pregnant mainlanders have prenatal exams before crossing the border. “We’re seeking [Beijing’s] assistance to hold the gate,” says Frank Choi, spokesperson for Hong Kong’s Health, Welfare and Food Bureau.

Hong Kong’s current baby boom owes its existence to two watershed decisions. One is the 2001 court ruling that granted residency to a child born in the city to mainland parents, and the other is Hong Kong’s 2004 decision to welcome individual tourists from China to stimulate the local economy. The result: over the last four years, the number of Chinese women who travel legally to Hong Kong to give birth and gain permanent residency for their offspring has risen thirteenfold.

Most experts forecast that the baby boom will continue unless China stops the outflow. That raises some big issues: will the children stay on, return later to study or work, or simply use what amounts to a passport of convenience to travel more freely than other mainlanders? Some opinion leaders, including former Hong Kong security boss Regina Ip, favor amending Hong Kong’s Basic Law to deny the right of abode to children of parents without residency. But others welcome the new blood. Hong Kong’s Legislative Council will start debating the issue next week. For his part, Dr. Leung has nothing against having mainland women arrive at his maternity ward each day. He just wishes they’d get proper checkups, and book hospital beds, before going into labor.