8 weeks pregnant: what is happening this week

Sixteen millimetres, raspberry-sized, and a change of terminology: from this week the NHS calls it a foetus rather than an embryo. The head is beginning to uncurl. Arms are lengthening and are running ahead of the legs, which are still working on knees, ankles, thighs and toes. The placenta is growing the branching structures that will anchor it to the wall of the uterus, and before long it takes over the job the yolk sac has been doing. Administratively this is the week the calendar becomes real. The booking appointment opens now - the NHS schedules it between weeks 8 and 12, it lasts about an hour, and it is mostly a long structured conversation rather than an examination. The first scan follows somewhere between weeks 8 and 14. Both need arranging rather than waiting for; the appointment is triggered by a phone call to a GP or midwife, and in most areas that call has to come from you. It is worth making it early in the window rather than late, because the scan that follows is what actually establishes the dating, and ACOG regards that scan as more accurate than any arithmetic done from a remembered date.