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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.