Noma yimuphi umntwana ozelwe ngokuhlangana: i-oocyte ohlangothini lukamama nesidoda ohlangothini lukababa. Ngamunye uletha izinto zakhe zofuzo:

• Ama-chromosome angu-22 + i-X chromosome eyodwa ye-oocyte
• Ama-chromosome angu-22 + i-chromosome engu-X noma engu-Y yesidoda

Ukukhulelwa kuzala iqanda elibizwa ngokuthi i-zygote, iseli lokuqala lapho ama-chromosomes omama nawomama ehlangene. I-genome bese isiqediwe: ama-chromosomes angama-44 nama-chromosomes amabili ocansi. Kusukela emhlanganweni ophakathi kweqanda nesidoda, zonke izici zengane sezivele sezinqunyiwe: umbala wamehlo akhe, izinwele zakhe, ukuma kwekhala lakhe, futhi-ke nobulili bakhe.

• uma isidoda besiphethe i-X chromosome, ingane ithwala ama-XX: kuzoba yintombazane.
• uma ephethe i-chromosome ye-Y, ingane izoba nama-XY pair: kuzoba umfana.

Ngakho-ke ubulili bomntwana buncike ngokuphelele emathubeni, kuye ngokuthi yisiphi isidoda esizophumelela ekuvundiseni i-oocyte kuqala.

Kusukela ngeviki lesi-6 lokukhulelwa, amaseli ezocansi akudala afakwa lapho amaqanda noma ama-testes azokhula khona kamuva. Kodwa noma ngabe isivele isilungisiwe ngokofuzo, kulesi sigaba ubulili bombungu buhlala bungahlukanisiwe. Ebafaneni, ipipi libonakala ngeviki le-12 lokukhulelwa (i-14 WA - inyanga yesi-3), futhi emantombazaneni, isitho sangasese sowesifazane siqala ukwakheka ngeviki lama-20 lokukhulelwa (22 WA, inyanga yesi-5) (1). Ngakho-ke ku-ultrasound yesibili yokukhulelwa (i-morphological ultrasound yamaviki angu-22) lapho kungenzeka khona ukwazi ubulili bomntwana.

• indlela ye-Shettles

Ngokomsebenzi wesazi sezinto eziphilayo saseMelika uLandrum Brewer Shettles, umbhali we Ungalukhetha Kanjani Ubulili Bengane Yakho2 (Indlela yokukhetha ubulili bengane yakho), isidoda esithwele i-chromosome yowesifazane (X) sihamba kancane futhi siphile isikhathi eside, kuyilapho isidoda esithwele i-chromosome yowesilisa (Y) sithuthuka ngokushesha kodwa siphila kafushane. Ngakho-ke umqondo ukuhlela ukuya ocansini ngokobulili obufunayo: kuze kube yizinsuku ezingu-5 ngaphambi kwe-ovulation ukukhuthaza i-spermatozoa ephikisana kakhulu ukuze ibe nendodakazi; ngosuku lwe-ovulation kanye nezinsuku ezimbili ezilandelayo ukukhuthaza isidoda esisheshayo kumfana. Kulokhu kunezelwa amanye amathiphu: i-pH yomlomo wesibeletho (i-alkaline ene-baking soda douche yomfana, i-acidic eneshawa yeviniga yentombazane), ukujula ne-axis yokungena, ukuba khona kwe-orgasm yabesifazane noma cha, njll. UDkt. Shettles ubika izinga lempumelelo elingu-75%… akufakazelwanga ngokwesayensi. Ngaphezu kwalokho, izindlela ezintsha zokuhlaziya isidoda azizange zibonise mehluko ku-anatomy noma isivinini sokunyakaza phakathi kwesidoda esingu-X noma se-Y (3).

• indlela kababa

Ngokuya ngocwaningo (4) olwenziwe ngeminyaka yama-80s esibhedlela sasePort-Royal sabakhulelwe kwabesifazane abakhulelwe abangama-200, le ndlela yasungulwa nguDkt François Papa futhi yanikezwa umphakathi jikelele encwadini (5). Isekelwe ekudleni okuhlinzeka ngosawoti wamaminerali athile ngezilinganiso ezichazwe kahle kuye ngocansi olufunayo. Ukudla okucebile nge-calcium ne-magnesium kungashintsha i-pH yesitho sangasese sowesifazane, okuzovimbela ukungena kwe-Y spermatozoa eqandeni, ngakho-ke kuvumela ukuba nendodakazi. Ngokuphambene, ukudla okucebile nge-sodium ne-potassium kungavimba ukungena kwesidoda esingu-X, kwandise amathuba okuba nomfana. Lokhu kudla okuqinile kufanele kuqalwe okungenani izinyanga ezimbili nengxenye ngaphambi kokukhulelwa. Umbhali ubeka phambili izinga lempumelelo lika-2%, elingaqinisekisiwe ngokwesayensi.

Ucwaningo (6) olwenziwa phakathi kuka-2001 no-2006 kwabesifazane abangu-173 bafunda ukusebenza kahle kokudla kwe-ionic kuhlanganiswe nokuhlela ukuya ocansini ngokosuku lwe-ovulation. Uma zisetshenziswe ngendlela efanele futhi zihlangene, lezi zindlela ezimbili zaba nezinga lempumelelo lama-81%, uma kuqhathaniswa nama-24% kuphela uma indlela eyodwa noma zombili zingalandelwanga ngendlela efanele.