The second prenatal checkup is usually at 16 weeks of pregnancy. 16 weeks is the time for the second prenatal checkup, in addition to the routine obstetric examination, the results of the first examination should be analyzed, including blood pressure, weight, height of the uterine fundus, fetal heartbeat, and a Down’s syndrome screening, and an additional ultrasound examination for high-risk pregnancies. 16 weeks is also the time for non-invasive prenatal examination and NIPT for those with high-risk factors or those over 35 years of age, which is Aneuploidy maternal serologic screening in mid-pregnancy is performed at 15-20 weeks. Amniocentesis for fetal chromosomes can also be done at 16-22 weeks if there are high risk factors. 16 weeks check-up should be done with routine calcium supplementation and 0.6-1.5g of iron daily. In case of PMS, ask about fetal movement and note that there is already fetal movement from 16 weeks.