By Yifan Wang

Hong Kong-listed shares of fertility companies, milk formula producers and infant product makers were sharply lower in Tuesday morning trade, paring the gains made late on Monday after China further relaxed its birth-control policy.

Assisted reproduction services providers Jinxin Fertility Group Ltd. and Suzhou Basecare Medical Corp. fell as much as 8.3% and 7.4%, respectively, by the mid-day trading break. The two stocks rose sharply in late trade on Monday, after Beijing said that it would allow all married couples to have as many as three children in response to China's aging population.

Infant milk formula makers also weakened from Monday's gains, as Health & Happiness (H&H) International Holdings Ltd. lost 5.7%, China Feihe Ltd. shed 3.0% and Ausnutria Dairy Corp. fell 3.6%. Stroller and crib maker Goodbaby International Holdings Ltd. declined 10%.

The deep losses for these companies in Hong Kong came in contrast with their peers in the mainland China market, where trading patterns tend to more closely follow shifts in government policy. Mainland-listed infant food maker Beingmate Co. and toy manufacturer Goldlok Holdings (Guangdong) Co. both surged 10%, the most they can gain daily.

Some analysts are worried that Beijing's latest measure won't be enough to turn around China's worsening demographic situation, with a once-in-a-decade census last month showing the country's population growth on the cusp of turning down after increasing rapidly for decades.

"Given the second-child policy didn't stop the birth decline, we don't expect the third-child policy to turn around the downtrend unless aggressive measures are adopted," Citi said in a research note on Tuesday, referring to Beijing's earlier policy to allow couples to have a second child.

Write to Yifan Wang at yifan.wang@wsj.com

(END) Dow Jones Newswires

06-01-21 0038ET