21 weeks pregnant: what is happening this week

26.7 cm head to toe, which the NHS likens to a carrot, and the measurement is now on the new basis so week-to-week comparisons make sense again. Lanugo continues to spread and holds warmth. Hair and eyebrows are growing. Noises and voices from outside are audible - not muffled abstractions but recognisable sound. Something else has started that will define the next four months: a sleep and wake cycle, and it is not going to align with anybody else's. Movement at eleven at night while lying still is not coincidence; it is the absence of the rocking motion that walking around all day provides. Balance is beginning to shift as the bump grows and the centre of gravity moves forward, which makes stairs, kerbs and turning round in a small kitchen genuinely less stable than they were. None of this is dangerous, and all of it is easier if the house is set up for it. Take the opportunity to notice which things in your home currently require standing on something.