Spousal age differences are highest in Sub-Saharan Africa, where trends in age at first marriage indicate an increase for both men and women. However, the net outcome for spousal age difference is difficult to predict without explicit analysis of these distributions. This study examines differentials in spousal age for women in first union. Further, it examines differences within population sub-groups and across countries, focusing on the influence of age at marriage and educational attainment. The analysis pools 144 survey datasets from the Demographic and Health Surveys (DHS) and Multiple Indicator Cluster Surveys (MICS) conducted between 1980 and 2020 in 34 countries. OLS regression analysis was used to predict the spousal age difference at marriage with five-year cohorts used to study time trends. The analysis finds a decline of 1.7 years in the spousal age difference at first marriage between the earliest (1980–1984) and most recent (2014–2019), indicating that there has been minimal reduction in age at first marriage over four decades, despite rising ages at marriage for females. Increasing age at first marriage and educational attainment of women partly explain the decline observed over time.