Second trimester milestones

ACOG's infographic says that by week 13 the major organs have formed and continue developing. Bones harden, particularly the long bones, while skin remains thin before gradually thickening. The neck becomes more defined, lower limbs develop further, hearing begins developing, and limb movements become more coordinated.

The lungs begin forming tissue needed for gas exchange after birth, but they are still far from mature. Ultrasound findings need clinical interpretation because a general week-by-week sequence cannot provide an individual prognosis.

Around this range, the fetus can hear sounds, the digestive system is working, and soft hair called lanugo begins covering the body. Ears, nose, and lips may be recognizable on ultrasound. A pregnant person may begin noticing movement as a fluttering, swirling, kick, or jerk, although recognition does not happen on one fixed date.

NHS guidance gives a broad 16-to-24-week window for first feeling movement. In a first pregnancy, it may be after 20 weeks. If no movement has been felt by 24 weeks, tell the midwife so the baby's heartbeat and movements can be checked. Do not use another person's experience as a deadline before that contact point.

ACOG describes kicks and turns becoming stronger during weeks 21 through 24. The fetus may bring a hand to the mouth, eyebrows are visible, and ridges that later become fingerprints and footprints form. The lungs continue developing, and patterns of sleep and rapid eye movement emerge.

A pregnant person will not perceive every fetal action described here. What becomes useful at home is familiarity with the baby's emerging movement pattern, not checking development against a daily list.

In England, the NHS 20-week screening scan is usually performed between 18 and 21 weeks. It looks for signs of 11 specified conditions and checks growth, the placenta, and blood flow in the uterus. The scan is optional, and the care team should explain what is offered and how to make an informed choice.

Screening cannot find every condition, and some findings are clearer than others. A reassuring scan does not certify every future outcome, while an unexpected finding may lead to further discussion or tests rather than an immediate conclusion. The NHS details here apply to England; programs, windows, and condition lists differ elsewhere.

There is no universal number of movements that every baby should make each day. NHS guidance says the important step is learning the baby's usual pattern. Movement should continue through the rest of pregnancy and during labor. A change in the familiar pattern matters more than reaching a generic count shown by an app.

Call the midwife or maternity unit immediately if movement is less than usual, stops, or changes from the usual pattern. Do not wait until the next day or rely on a home Doppler. Hearing a heartbeat does not show that the baby is well. A tracker may hold notes, but direct assessment must not be delayed.