The impact of eliminating sterility on population growth.

Abstract

The issue of this discussion is whether and to what extent treatment of infertility will contribute to a significant increase in fertility, and whether treatment of sexually transmitted diseases and infertility is justified as a humane effort to alleviate suffering, death, and the extent of impact on men, women, fetuses, and infants. The Brunham model produces estimates of the difference in the total fertility rate (TFR) due to sterility of between 9.7 and 18.0. However estimates with more realistic assumptions about life expectancy, menarche, menopause, and union formation yield TFR differences between 2.1 and 2.5. Accounting for secondary sterility and a more realistic simulation yields a change in the population growth rate of 0.8% and 0.9% compared to 2.5% and 1.9% in the Brunham model. The conclusion is that population growth rates would not be very likely to increase if sterility is eliminated. The Brunham model is an important attempt to model the effects of different assumptions about rates of partner exchange on disease prevalence and on sterility levels. The Brunham conclusion is that population growth rates increase by 50% or more when gonorrhea has a prevalence of 20% and a 12% probability of sterility per 6-month duration of illness. Chlamydia-related secondary sterility would not have quite as large an effect. Many other models are possible because of the many other fertility inhibiting factors. The Brunham model does not account for any age variation in fertility and mortality rates, which is not a realistic view of human behavior. The Brunham model also uses a very high mortality pattern, comparable to TFRs of 8.5 to 9.5 for a noncontracepting Hutterite natural fertility population, with short breast feeding, and universal marriage. When fecundability, exposure to risk of intercourse, postpartum and lactational amenorrhea, and coital frequency are taken into account, the impact of sterility is reduced. The proposed model accounts for sterility and postpartum amenorrhea, union formation, and coital frequency with realistic ages of menarche and menopause.