I dont think the technology is avaliable in singapore to choose the gender of the child. You can try referring to the chinese calendar using a combination of ur age and month of conceive. No guarantee though..
I heard alkaline environment in the vagina creates better opportunity for male sperms (Y)
Take alkaline foods, your partner should drink more caffeine beverage.
But no 100% guarantee.
Actually girls are equally good, as long as your children are healthy. Hope you dont get pressurised
