The aim of this magister thesis is to examine the motives behind parents´ choice to sex determine their children, or not, at routine ultrasound examination (RUL). The analysed empirical data consists of 261 responding questionnaires written by expecting parents. My conclusions are that the motives behind parents’ choice can reflect their view of sex as binary or analog. Many parents sex determine their unborn children in order for preparing their rooms, clothes and toys to correlate with the heterosexual matrix. Girls get pink and boys blue, but the colours are of course only the visible part of how children are sexed as social construction. Some parents are experiencing a peer pressure and quite a few parents are influenced by the midwife performing the RUL to chose to sex determine their child. The most common motive to abstain from sex determining the child at RUL is after all to make gender the big happening at birth. Parents prepare to raise – not a child – but a boy or girl.