EFrance, usuku olulindelekile lokulethwa lulindelwe ngokuhlelekile ezinyangeni eziyisishiyagalolunye ngemuva kosuku olulindelekile lokuqala kokukhulelwa, okungukuthi amasonto angama-41 (amasonto e-amenorrhea, okungukuthi amasonto angenazikhathi) (1). Isibonelo, uma usuku lwesikhathi sokugcina kungu-Mashi 10, ukuqala kokukhulelwa kuyalinganiselwa, esimweni semijikelezo ejwayelekile ye-ovulatory, Mashi 24; i-DPA ngakho-ke isethwe ngoDisemba 24 (Mashi 24 + 9 izinyanga). Ukwenza lokhu kubalwa, udokotela wezifo zabesifazane noma umbelethisi usebenzisa i- "disc disc".

Kodwa-ke, lolu wusuku lwethiyori kuphela izinto ezahlukahlukene ezingaba nomthelela kuzo:

• ubude bomjikelezo: le ndlela yokubala isebenza emijikelezweni ejwayelekile yezinsuku ezingama-28
• usuku lokuvuthwa olungahlukahluka, noma kumjikelezo ojwayelekile, noma kusuka komunye umjikelezo kuye komunye
• isikhathi sokuphila seqanda nesidoda, okungathinta usuku lokukhulelwa

Elinye ithuluzi lizokwenza kube nokwenzeka ukuqinisekisa noma ukulungisa lolu suku lokuqala lwethiyori: i-ultrasound yokuqala yokukhulelwa eyenziwa ngo-12 WA futhi ngaphezu kwalokho ibizwa nge- "dating ultrasound". Ngalesi sikhathi se-ultrasound, udokotela uzobala isibalo semibungu, ahlole ubungqabavu bayo bese enza i-biometry (ethatha izilinganiso) ezokwenza kube lula ukulinganisa iminyaka yokukhulelwa futhi nosuku olulindelekile lokubeletha. Izokalwa:

• ubude be-cranio-caudal noma i-LCC, obuhambisana nobude bekhanda ukuya ezinqeni bombungu
• ububanzi be-biparietal noma i-Bip, okungukuthi ububanzi bogebhezi

Lawa maxabiso amabili aqhathaniswa namajika ayizethenjwa futhi avumela ukuphola kokukhulelwa kanye nokulinganiselwa kweminyaka yobudala bombungu kungakapheli izinsuku ezintathu. Le ultrasound ibhekwa njengendlela engcono kakhulu yokukhulelwa kwezithandani (3).

Noma i-ultrasound ikwazi ukuthembela esikhathini sokukhulelwa, kunenye idatha engathinta usuku lokulethwa: isikhathi sokukhulelwa uqobo. Kodwa-ke, lokhu futhi kuyisilinganiso; ngaphezu kwalokho, emazweni amaningi, isikhathi sokukhulelwa asibalwa ezinyangeni eziyi-9 kepha ngesonto ngaphambili, okungukuthi amasonto angama-40. (3) Ngokuya ngezindlela zokubala, izici zofuzo kanye nezici ezithile zomama, isikhathi sokukhulelwa siyahluka phakathi kwezinsuku ezingama-280 nezingama-290 kusukela osukwini lokuqala lwenkathi yokugcina (kumjikelezo ojwayelekile wezinsuku ezingama-28). Isikhathi sokukhulelwa siyehluka phakathi kwamaviki angama-40 + 0 kanye nama-41 + 3 (4). Ucwaningo lwakamuva (5) luye lwabonisa nokuthi ubude besikhathi obusukela ekukhulelweni kweqanda kuye ekubelethweni kwakuyizinsuku ezingama-268 (okungukuthi amasonto angama-38 nezinsuku ezi-2) ngokungafani okuqinile (kuze kube amasonto ama-5) kuya ngomama.