What is the primary characteristic of a molar pregnancy?

The primary characteristic of a molar pregnancy is an abnormal growth of trophoblasts. In a molar pregnancy, the trophoblastic tissue, which would normally develop into the placenta, grows excessively and chaotically instead of forming a viable pregnancy. This abnormal growth leads to the formation of abnormal structures called hydatidiform moles, which can be either complete or partial.

In a complete molar pregnancy, there is usually no normal fetal development, as the genetic material is entirely paternal, resulting in an abnormal configuration that cannot sustain life. In a partial molar pregnancy, there may be some fetal tissue, but it is often malformed and nonviable.

The presence of this abnormal growth is significant because it can lead to various complications, including the risk of developing gestational trophoblastic neoplasia, which can lead to malignancy if not properly managed. This area of abnormal tissue growth is what distinguishes molar pregnancies, emphasizing the importance of understanding trophoblastic pathology in obstetric care.