Birth intervals Children 2 Contraceptives 2 Fertility, Human 2 Health and hygiene 2 Infants 2 Mortality 2 tuilleadh ... Mothers 2 Physiological effect 2 Birth control 1 Breastfeeding 1 Child 1 Complications 1 Contraception 1 End of the world 1 Extinction (Biology) 1 Female 1 Growth 1 History teachers 1 Human rights workers 1 Humans 1 Infant 1 Infertility, Male 1 Population 1 Pregnant women 1 Twenty-first century 1 lúide ...