When do you do four late?

The third trimester refers to the pregnancy after 28 weeks, then routine B ultrasound examination, generally in 32 weeks of pregnancy, 37 weeks of pregnancy and 40 weeks of pregnancy. 32 weeks of pregnancy B ultrasound, mainly clear fetal position is head or breech, if breech, need to start correction. Generally, amniotic fluid and umbilical blood flow should also be measured as indicators to judge fetal safety. If there is any abnormality, it should be combined with more objective examinations such as fetal heart monitoring to make an assessment. B ultrasound at 37 weeks and 40 weeks of pregnancy, similar to that at 32 weeks, is also to check fetal position, assess fetal size, and fetal safety.