Routine examination, amniocentesis to check fetal chromosomes and Down’s syndrome screening in the 4th month of pregnancy. 1. Routine examination: including weight, blood pressure, measuring the height of the uterine fundus and listening to the fetal heart rate. 2. Amniocentesis for fetal chromosomes: an invasive test, amniocentesis is needed for chromosome examination when fetal abnormalities are suspected, usually performed around 16~22 weeks of pregnancy. 3. Down’s syndrome screening: Down’s syndrome screening can be done at 16~18 weeks of pregnancy, through which it can determine whether there is any chromosomal abnormality in the fetus. Currently, Down’s syndrome screening can be done through ultrasound screening and human chorionic gonadotropin in the serum to calculate the risk. If you have any other questions, it is recommended that you consult a medical professional for guidance.