22 weeks pregnant: what is happening this week

27.8 cm, sweet-potato sized, and the lungs have started rehearsing. Breathing movements happen in fluid, which does nothing for gas exchange and everything for building the muscle and coordination that will be needed in one specific moment several months from now. Amniotic fluid is being swallowed; what is not absorbed becomes meconium, the dark sticky first nappy contents. Taste buds are forming, and what is eaten shows up in the fluid. Movements are strong enough now that a hand on the bump sometimes gets an answer, though whether the answer is a response or a coincidence is unknowable and beside the point. Stretch marks may be appearing on the stomach, thighs and breasts. The vaccination window remains open for whooping cough. There is a habit worth forming this week: paying attention to the pattern of movement rather than counting it. The NHS is clear that there is no set number of movements to expect and no chart to hit; what matters is what is usual for this particular pregnancy, and noticing a change from it.