PINK OR BLUE? Can you try for a boy or girl?

Is it re­ally pos­si­ble to con­ceive a boy or girl by choos­ing the time of con­cep­tion ac­cord­ing to your cy­cle?

Your Pregnancy - - Contents - BY JU­LIA BOLTT YP

There are plenty of old wives’ tales about how to con­ceive the gen­der of your choice. Have you heard about hav­ing sex un­der a full moon to con­ceive a girl, or a quar­ter moon for a boy? Try the mis­sion­ary style for a girl or stand­ing up for a boy, or fac­ing a cer­tain way (plac­ing the head of the bed to the north) for a boy. To get a girl, eat choco­late and for a boy, you must eat red meat. Yes, re­ally. How­ever, it’s best to take all th­ese bits of lore with a large pinch of salt. In re­al­ity, which­ever method you opt for, you have about a 50 per­cent chance of hav­ing a baby of ei­ther sex.

WHAT DE­TER­MINES A BABY’S SEX?

It’s ac­tu­ally the sperm that de­ter­mine the sex of your baby. The egg a woman ovu­lates car­ries an X chro­mo­some, while sperm carry ei­ther an X or a Y chro­mo­some. If the sperm with an X chro­mo­some fer­tilises the egg (XX), the em­bryo will de­velop into a girl baby, while an XY em­bryo, fer­tilised by sperm with a Y chro­mo­some, will de­velop into a boy baby.

IS TIM­ING EV­ERY­THING?

There is a widely-held be­lief that boy sperm are faster, but more frag­ile, than girl sperm, which are sup­pos­edly slower, but more re­silient. In fact, the Shet­tles Method works on this as­sump­tion and ad­vo­cates us­ing timed in­ter­course on spe­cific days of your cy­cle to in­crease your chances of hav­ing ei­ther a boy or a girl. The ba­sis of the method is that Y chro­mo­some sperm move faster, but don’t live as long as sperm car­ry­ing X chro­mo­somes, so you should have sex as close as pos­si­ble to ovu­la­tion to con­ceive a boy, whereas for a girl, you should have sex two to four days be­fore you ovu­late. Not ev­ery­one’s cy­cle is stan­dard though, so you’d need to use an ovu­la­tion pre­dic­tor kit or chart your basal body tem­per­a­ture to know for sure when you’re ovu­lat­ing. Another method that sup­pos­edly works on the tim­ing of in­ter­course is the Whelan Method, which di­rectly con­tra­dicts the Shet­tles Method. The the­ory be­hind this method is that bio­chem­i­cal changes that may favour boypro­duc­ing sperm hap­pen ear­lier in your cy­cle, so if you want a boy, you should have sex four to six days be­fore your basal body tem­per­a­ture goes up. If you want a girl, have sex two to three days be­fore you ovu­late. You’d need to chart your basal body tem­per­a­ture ev­ery day to fig­ure out when you’re ovu­lat­ing. How­ever, there’s no sci­en­tific ev­i­dence that ei­ther of th­ese meth­ods work. They’ve all got about a 50 per­cent chance, com­ments re­pro­duc­tive medicine spe­cial­ist Dr Yossi Un­ter­slak of Vi­ta­lab. The same is true of sperm wash­ing, which pur­ports to sep­a­rate male and female sperm, “and that as well is re­ally a 50/50 chance, but there’s re­ally no good sci­ence to this,” he adds.

GET­TING TECH­NI­CAL

It is pos­si­ble to se­lect the sex of your baby and leave noth­ing to chance by us­ing the magic of sci­ence. In-vitro fer­til­i­sa­tion (IVF) utilises test­ing that can in­di­cate sex. How­ever, the law in South Africa is very clear: choos­ing the sex of your baby for so­cial (not med­i­cal) rea­sons is il­le­gal. Specif­i­cally, the law states that: “Pre-im­plan­ta­tion and pre­na­tal test­ing for se­lect­ing the sex of a child is pro­hib­ited, ex­cept in the case of a se­ri­ous sex-linked or sex- lim­ited ge­netic con­di­tion.” There are sit­u­a­tions where there is a valid med­i­cal rea­son for se­lect­ing a par­tic­u­lar sex. “Be­cause spe­cific dis­eases are linked to gen­der, in those cases – to elim­i­nate the dis­ease or elim­i­nate the risk of hav­ing a child with that dis­ease – you are able to se­lect sex,” says Dr Un­ter­slak. There are a num­ber of pre­na­tal tests that can be used. PGS (pre-im­plan­ta­tion ge­netic screen­ing) is a screen­ing test that looks at the em­bryo’s chro­mo­somes for dele­tions or ad­di­tions. This de­tects chro­mo­so­ma­lly ab­nor­mal em­bryos that would re­sult in IVF fail­ure, mis­car­riage or ba­bies born with Down syn­drome, Ed­wards syn­drome (Tri­somy 18), Turner syn­drome and some other ge­netic con­di­tions. Pre-im­plan­ta­tion ge­netic di­ag­no­sis (PGD) is spe­cific to cer­tain ge­netic dis­eases. This would be utilised by par­ents who are car­ri­ers of a se­ri­ous ge­netic dis­ease and who want to avoid a se­ri­ous in­her­i­ta­ble ge­netic dis­ease, some of which are sex-linked and af­fect mainly males, such as cys­tic fi­bro­sis, Duchenne mus­cu­lar dys­tro­phy and other sin­gle­gene dis­or­ders.

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