Young families have been flocking to clinics in China's large cities over the past week due to widespread concern over milk powder produced by a Chinese company that is alleged to have caused three infant girls to grow breasts.

A toddler gazes out from the toy car attached to his mother's shopping cart on Aug 11 as she looks at the milk powder products on the shelves of a supermarket in Weifang, East China's Shandong province. [Xinhua]

On Aug 9, three female infants in Wuhan of Central China's Hubei province were reported suffering abnormal sexual development. Doctors and parents suspected the milk powder they had been using contained sex hormones.

Although the Ministry of Health said on Sunday that its investigation found no evidence that the formula made by NASDAQ-listed Synutra had caused the babies to develop breasts, concerns over children's health came to the forefront in some Chinese cities.

In Shanghai, experts estimated at least 30,000 children developed early maturity in the city, local media reported.

Shanghai pediatrician Huang Xiaodong said that around 20 percent of sexually precocious children he had treated were younger than 2 years old.