Not a day goes by when Wen Bing isn't wracked with guilt over his failure to have a premarital medical check, an omission that led to the death of his 9-year-old son.

Speaking of his son, who died nine years ago, the 35-year-old said: "He had soft hair and tender eyes. He was a mild boy. His death left a wound in my heart that will never heal."

Wen's son was 4 months old when he was diagnosed with thalassemia - a hereditary blood disorder that causes severe anemia - at a hospital in Guangzhou, Guangdong province. Wen and his wife cried when the doctors told them their son's condition could have been predicted if they had chosen to have premarital checks.