As an increasing number of couples, many past their reproductive prime, seek to have a second child under China's new two-child policy, challenges exist including poor sperm quality, experts said.

According to official estimates, 60 percent of the couples who are newly eligible for a second baby are age 35 or older, and many of these are visiting fertility specialists for advice or assistance.

Physician Long Wen, who works for the fertility center of Renmin Hospital of Wuhan University in Hubei province, said that more than half of his male patients had "substandard" sperm quality.