Inqanaba lokuzala, elibizwa ngokuba lizinga lokuzala, lilinganiso echanileyo yokuzalwa kwendawo okanye kwihlabathi. Ikwahlula inani eliqhelekileyo lokuzalwa okuza kubakho kuwo onke amabhinqa aneminyaka yobudala bokuzala, kungakhathaliseki ukuba ngaphandle kwezinto kunye nokufa. Izinga lokuzala libonakalisa utshintsho olunokwenzeka kwisakhiwo sabantu belizwe.
Umlinganiselo wezinga lokuzala
Ukubala izinga lokuzala, inani labantwana abazalwe ngexesha elithile kufuneka lihlulwe ngokwenani labasetyhini abaneminyaka eli-15-49 (iminyaka yobudala) kwaye banda ngo-1000. Izinga lokuzala libalwe kwi-ppm (‰).
Ngokufa okunciphisa kakhulu ukutshintshwa kwezizukulwana, isantya sokuzala sinokuthi sibe kwizinga le-2.33. Ukuba izinga lokuzala lilingaphezu kwe-2.4 - oku kukuzala okuphezulu, ngaphantsi kwe-2.15 - phantsi. Umlinganiselo wokuzala wabantwana abali-2 ngomfazi ngamnye uthathwa njengomlinganiselo wokuzala. Inani elikhulu libonisa iingxaki zengxaki ezibonakalayo zabazali eziphathelene nokufundisa nokuxhasa abantwana babo. Ukuzala okuncinci kunceda ekuguga kwabantu kunye nokunciphisa inani labo.
Ukunyamekela ngamazwe ehlabathi
Iimpawu zerhafu jikelele yokuzala kwiplanethi yethu yinkqubo yokwehla kwemali. Ngelishwa, kuqikelelwa ukuba le nto iya kuqhubeka, ubuncinane kwiminyaka engama-30 ezayo. Ngoko, umzekelo, ukuzala eRussia uye waya kwinqanaba le-1.4 ngokuqwalasela abemi baseCaucasus, ngokuqhelekileyo "ngaphezulu". Kwaye inani elifanayo e-Ukraine sele li-1.28. Nangona ngaphantsi kwezinga lokuzala phakathi kwabakwaBelarusiya kuphela 1.26 ngeyonke.
Inani elipheleleyo lokuzala
Ngokubanzi, ukuncipha kwenzala kubonakala kulo lonke ihlabathi. Uninzi lwalo mkhangeli lubonakala kumazwe ashishino lwaseYurophu eNtshona Koloni, ebonakaliswa ngokuncipha kwezinga labantu.
Ngethuba lokusukela ngo-1960-2010, isantya sokuzala emhlabeni wonke sehla ukusuka ku-4.95 ukuya ku-2.5648 ngokuzalwa komfazi ngamnye. Kwamazwe amaninzi aphuhlisiwe, ukuzala okunjalo kubhalwe ngaphambili kwiminyaka yama-1960, kwaye ngo-2000 bekuye kwehla kwi-1.57. Ngoku inqanaba eliphantsi kakhulu lokuzala emhlabeni lihlala eSingapore (0.78), kwaye liphezulu kwiNiger (7.16).