Heterogeneous effects of socio-economic and cultural factors on fertility differentials in Burundi and Morocco during their fertility transition periods: a retrospective, cross-sectional and comparative study.

Introduction: few studies have examined the factors influencing fertility differentials and the variation in their effects in countries with different socioeconomic and cultural backgrounds and different fertility transition paces. To address this gap, our study sought to first identify the factors that influenced fertility differentials in Morocco and Burundi during their fertility transition periods, and then to compare the effects of these factors between the two countries.

Methods: using data from the 2003-4 Morocco and 2010 Burundi Demographic and Health Surveys, bivariable and multivariable Poisson regression analyses offset by the natural logarithm of the women´s age were performed to identify the socioeconomic and cultural factors that influenced fertility differentials in Morocco and Burundi during their fertility transition.

Results: our main findings showed that the total number of children ever born ranged from 0 to 17 with a mean of 2.71 ± 2.89 in Burundi and from 0 to 16 with a mean of 1.88 ± 2.80 in Morocco. In Burundi, both socioeconomic and cultural factors like rural residence adjusted incident rate ratio (AIRR) = 1.159, 95% CI: 1.103 - 1.217, P=0.020), women´s illiteracy (AIRR=1.465, 95% CI: 1.241- 1.729, P <0.001) and agricultural profession (AIRR=1. 332, 95% CI: 1.263 - 1.401, P = 0.004), household poverty (AIRR= 1.381, 95% CI: 1.223 - 1.431, p<0.001), infant mortality (AIRR= 1.602, 95% CI: 1.562 - 1.643, p<0.001), early marriage (AIRR= 1.313, 95% CI: 1.264 - 1.364, p<0.001), lack of knowledge of any contraceptives (AIRR= 1.263, 95% CI: 1.125 - 1.310, p = 0.003) and failure to use modern contraceptives (AIRR= 1.520, 95% CI: 1.487 - 1.611, p<0.001) were associated with high number of children ever born. However, in Morocco socioeconomic factors like residence place, women´s agricultural profession and household poverty were not significant. In this country, women´s illiteracy (AIRR=1.428, 95% CI: 1.315 - 1.551, P <0.001), lack of access to mass media (AIRR= 1.241, 95% CI: 1.108 - 1.375, p = 0.006), infant mortality (AIRR=1.222, 95%CI: 1.184 - 1.361, p<0.001), early marriage (AIRR1.481, 95% CI: 1.435 - 1.529, p<0.001), lack of knowledge of any contraceptives (AIRR1.508, 95% CI: 1.409 - 1.613, p<0.001) and failure to use modern contraceptives (AIRR1.745, 95% CI: 1.627 - 1.863, p<0.001) were associated with high fertility but with different effects than in Burundi.

Conclusion: the evidence from this study suggests that interventions to accelerate the fertility transition processes in Burundi and many other countries with slow fertility transitions should be designed and implemented according to each country's local context.