Abaphandi baseMerika bafika kwisigqibo sokuba abantwana abazalelwe ngaphambi kwesikhathi, ngokuphindaphindiweyo, bahlala bengenamntwana
Esi sigqibo sifikelelwe ngabasosayensi baseMelika ababethelela i-1.2 million yabantu abazalwa eNorway ukususela ngo-1967 ukuya ku-1988. Ngokomphandi ovela kwiZiko lezeMpilo kwiYunivesithi yaseDuke, malunga nabantwana abangaba ngu-60 000 abazalwe ngeli xesha bazalwa ngaphambi kwesikhathi. Kamva amakhwenkwe, azalwe kwiiveki ezingama-28-32. Bebebawo-30% abangaphantsi kancinane kunezo zazalelwa ngexesha. Ekuzaleni kwexesha elincinci lokukhulelwa, ingozi yokungabantwana yayanda, uGeeta Swami, inkokeli yokufunda, yaziswa. Abafana abazalelwe ngeveki ezingama-22-27. ukukhulelwa, bafumana inzala yabo ngo-76% ngaphantsi kwalabo bazalwa kwiiveki ezingama-37 ukuya kuma-40. Kwaye amantombazana azalwe ngalo mhla aba ngabantwana abangama-67% amaninzi ngaphezu kwabo bazalwa ngexesha.