What is commonly measured at 12 weeks of gestation?

At 12 weeks of gestation, the size of the uterus is typically measured and is expected to have risen out of the pelvic cavity. This is a key milestone in pregnancy, as by this stage, the uterus is large enough to extend above the pubic bone, making it palpable during a physical examination. This rise is significant because it indicates the growth and development of the fetus and allows healthcare providers to monitor the progress of the pregnancy.

While other options may also be relevant at different points in pregnancy, they either do not specifically pertain to the 12-week mark or are less commonly assessed at this stage. The baby's heartbeat is usually detected by an ultrasound or a Doppler device around this time, but it isn't a direct measurement like the size of the uterus. Similarly, monitoring the level of amniotic fluid or evaluating the mother’s weight occurs later in pregnancy or is influenced by factors that become more apparent as gestation progresses. Thus, measuring the size of the uterus rising out of the pelvic cavity is the most relevant and commonly performed assessment during this time.