China registered a sex ratio at birth of 117.7 boys for every 100 girls in 2012, marking the fourth year of decline, the People's Daily reported on Tuesday, citing figures from the National Population and Family Planning Commission (NPFPC).

A normal ratio should stand at 103 to 107 boys for every 100 girls, considering the discrepancy in mortality rates between the two genders.

The decline is a reflection of China's successful efforts to curb an imbalance in the ratio, which reached a record high of 121.2 boys for every 100 girls in 2004, the NPFPC said, adding that the imbalance remains problematic.

The figures for the previous three years were 119.45 in 2009, 117.94 in 2010 and 117.78 in 2011.

Boys are traditionally preferred over girls in China. The sex ratio at birth has hovered at a high level since fetal ultrasound exams became common in China in the 1980s. The one-child policy has further complicated the issue.