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This paper focuses on the role of uncertainty about the number of surviving children. The survey discusses the effects of declining mortality rates on fertility, education and economic growth. The construction of the paper is an OLG model in which individuals make choices about fertility decision over their lifetimes subject to uncertainty about the immortality. The simulation of model using actual changes reveals the fact that if the uncertainty about child survival enters to growth model, the population becomes an inverted u-shaped function of income per capita. As the mortality rate and thus uncertainty falls, the precautionary demand for children decreases. Furthermore, lower mortality encourages investment in children’s education .Also the calibrated version of the model using realistic estimates demonstrates that at low levels of income, population growth rises leading to Malthusian steady-state equilibrium, whereas at high levels of income population growth declines leading to a sustained growth steady-state equilibrium.

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Changes infertility ratesasone of the factors affecting the demographic changes and its rolein the labor supply and there fore economic growth, as an important element ofsocio-economic development of every country is considered. So that the importance of demographic changes in each country in recent years has increased resulting aging population in general and specifically decreased fertility that increased concerns for the global economy and the majority of developing countries-including Iran. However, the range of empirical studies in incurred countries is very limited and in most studies, the surface shape of the subject has investigated in a simple line a reconometric model. Thus this study investigates the impact of fertility’s changes one conomic well-being in selected MENAcountries over the 1970-2010. We apply dynamic consumer optimization model that incorporates end ogenous fertility as well as end ogenous education and health investments offered by Prettner and et al. (2013). The estimation results of non-linear panel smooth transition regression model reports the negative effect of fertility and positive effect of revenue and population on effective labor force, which show that the quantity-quality trade off in population acts in favor of labor force and increases its quality and causes output growth and well-being. This issue is in ferable from positive effect of population on education and health-as delineator indices for well-being- in the countries under investigation.