This document discusses various diagnostic modalities used during pregnancy to monitor the health of the mother and fetus. It describes non-invasive methods like ultrasounds, non-stress tests, contraction stress tests, and measuring the amniotic fluid index. Ultrasounds use soundwaves to create images and can be done abdominally or transvaginally. Non-stress tests monitor fetal heart rate responses during movements. Contraction stress tests evaluate the fetus' ability to handle contractions. The amniotic fluid index uses ultrasounds to measure pockets of amniotic fluid in quadrants. Invasive methods like amniocentesis are also discussed.