This study seeks to assess fertility data in Swaziland based on the 1976, 1986, 1997 and 2007 censuses. By utilising single-year age-sex published raw data, demographic evaluation tools—sex ratio, age ratio, Whipple’s index, and modified Whipple’s index—were used to assess age misreporting as several fertility measures rely on the quality of age data. In addition, using published descriptive census tables for women in the reproductive lifespan, 15–49, data on children ever born or parity (P) derived were evaluated for incorrect reporting of parities using the el-Badry technique. Further, the relational Gompertz model was applied to adjust data on reported aggregated births in the last year or current fertility (F) relying on its intrinsic P/F ratios feature as an adjustment and diagnostic tool for consistency checks on fertility and parity distributions. The evidence of some age reporting distortions or age misreporting is not too severe, but moderate, and therefore fertility estimates in the four censuses of Swaziland cannot be said are invalidated. The data on parity and current fertility conforms to expected or typical patterns of fertility distributions of African populations. The study concludes that the census data were of reasonable quality for fertility estimation.