Foetal ultrasound scan of an 11-week-old foetus. At this stage of the pregnancy, all the major body organs have formed and the most critical period in development has passed. It is not yet possible to determine the gender, as the sex organs are not externally visible. The foetus can suck and swallow, and the intestines can process the liquid that is swallowed. The foetus can kick, punch, flex its fingers, form a fist and wrinkle its forehead. The size of the foetus can be measured, so that the due date can be established. A scan at this stage can also detect Down's Syndrome, by measuring the thickness of the skin at the back of the foetus' neck (nuchal translucency).