What is the duration of the third trimester of pregnancy?

The third trimester of pregnancy is defined as spanning from the 28th week to the 40th week. This period is critical as it involves significant growth and development of the fetus, culminating in preparation for birth. By 28 weeks, the fetus is generally considered to be moving into a stage where lung development and fat accumulation become essential for survival outside the womb.

The cutoff at 40 weeks typically marks the end of a full-term pregnancy, although it is common for many pregnancies to go into the 41st week. Recognizing this timeframe is important in prenatal care, as it helps healthcare providers plan for labor and delivery, monitor fetal development, and prepare for potential complications that may arise as the due date approaches.

While other ranges provided in the options do define significant stages of pregnancy, they do not accurately represent the recognized gestational weeks associated with the third trimester. Each of these alternatives either starts too early or ends too late, making them inconsistent with standard medical definitions.