The official Xinhua News Agency on Wednesday quoted Wen as saying the "government will adhere to the basic policy of family planning with improved services and stronger leadership."
He added that family planning was crucial to China's modernization and the building of a "harmonious society," a catchphrase meant to mean a more equal distribution of riches in a country with a growing wealth gap.
Wen told a conference on population and family planning that the family planning priority was China's highly populated countryside, where maintaining a low birth rate was crucial.
He said more rewards and subsidies were needed for rural people, including social insurance to encourage birth control.
Up to 800 million of China's 1.3 billion people live in the countryside, where children, especially boys, are considered the best way to make up for the country's limited social safety net.
The communist government has limited most urban couples to one child and rural couples to two since the 1970s to try to restrain the growth of China's population and conserve scarce resources.
Critics say the policy has led to forced abortions, sterilizations and a dangerously imbalanced sex ratio due to a traditional preference for male heirs, which has prompted countless families to abort female fetuses in hopes of getting boys.
Government statistics show that 117 boys are born for every 100 girls in China, well above the average for industrialized countries of between 104 and 107 boys for every 100 girls.
Experts have said the gender imbalance resulting from sex-selective abortions and other practices could have dangerous social consequences due to anticipated shortages of marriageable young women.
State Councilor Hua Jianmin was quoted as telling the same conference that gender identification for non-medical purposes would be severely punished and policies advocating the rights of girls and women as well as gender equality and birth control would be promoted.
There are also concerns about China's aging population, with those aged 60 or older expected to top 200 million by 2015 and 280 million by 2025, according to the government.
Last month, Zhang Weiqing, the minister in charge of the State Population and Family Planning Commission, said China's population would be 400 million higher if not for the government's family planning policies.