What is the primary purpose of an ultrasound during pregnancy?

The primary purpose of an ultrasound during pregnancy is to assess fetal size and health. Ultrasounds are a crucial diagnostic tool that allow healthcare providers to visualize the developing fetus within the womb. This imaging technique helps in determining the gestational age of the fetus, monitoring growth patterns, checking for anatomical abnormalities, and ensuring the fetus is developing appropriately.

By evaluating the fetal size and overall health, clinicians can identify potential issues early in the pregnancy, which aids in planning appropriate care and interventions if necessary. Ultrasounds can also provide critical information about the placenta and amniotic fluid, contributing further to understanding the pregnancy's progression and fetal well-being.

The other choices, while related to pregnancy care, do not directly reflect the main role of ultrasound. Monitoring maternal blood pressure, determining the mother's weight, and predicting labor duration are important aspects of prenatal care, but they are not the primary functions of an ultrasound examination. These factors can be assessed through other means and do not involve imaging the fetus directly.