The NDHS 2003, however, noted that the difference between the rates may not indicate an increase in infant mortality, but rather reflects an underestimation during the previous surveys.
但是2003年尼日利亚人口卫生状况调查显示婴儿死亡率之间的差异并不说明婴儿死亡率的上升，而是反映以前调查中出现低估。