Fertility level in sub-Sahara Africa countries (SSA) such as Nigeria still remain high. This can be attributed to early marriage in most countries in sub-Sahara Africa. Maternal age of mothers has the tendency of determining level of fertility behaviour. It also has implications on reproductive health conditions of women most especially in northern Nigeria. Reproductive health of women in the Northern region of Nigeria in terms of family planning is very poor due to low age at marriage thereby leading to high fertility behaviour in terms of children ever born (CEB) in the region. This study made use of cross-sectional study design of secondary data extracted from the 2021 multiple cluster indicator survey (MCIS) on selected socio-demographic variables of children ever born (CEB) and maternal age in the region in examining the association and relationship between maternal age and fertility behaviour in terms of children ever born (CEB) in the region. Findings revealed that maternal age is associated with children ever born (CEB) in northern Nigeria with: χ2=1,649, p=0.000; χ2=2,248.85, p=0.000 andχ2=3,352.157, p=0.000 for north central, north east and north west region respectively at 0.05 level of significance. Multivariate analysis also revealed relationship between maternal age and fertility behaviour in the region with: Prob>F = 0.0000, R. Squared 0.045 at 5% level of significance. It was concluded that there is need for the Nigerian government to improve on girl child education in the northern Nigeria as this will help in reducing early marriage in the region. The government also need to address issues relating to women empowerment as this will go a long way in improving women autonomy in terms of financial autonomy there by reducing the tendency of girls been forced to early marriage because of financial benefits.