"Do Many Deformities Occur During the Third Trimester?"

1. When pregnant mothers reach a certain stage of pregnancy, B-mode ultrasound often reveals various issues. In fact, before 12 weeks of pregnancy, various factors, such as medication, external environment, and chromosomal mutations during embryonic development, may cause developmental abnormalities. However, in the early stages, the fetus is too small for B-mode ultrasound to detect these abnormalities. This is why a detailed anomaly scan, also known as a systematic B-mode ultrasound, is conducted at 22 weeks of pregnancy to assess the fetus's development at this stage.

2. Additionally, a routine B-mode ultrasound is performed between 30 and 32 weeks of pregnancy to observe the fetus's developmental status. While significant issues and large physical anomalies can be detected through B-mode ultrasound, some smaller anomalies may not be visible. During pregnancy, some common anomalies involve cardiovascular issues, such as heart development problems. Of course, primarily, external anomalies such as limb deformities and significant cranial issues can also be observed through B-mode ultrasound.