Arterial Blood Gases. Test Overview. An arterial blood gas (ABG) test measures the acidity (pH) and the levels of oxygen and carbon dioxide in the blood from an artery. This test is used to check how well your lungs are able to move oxygen into the blood and remove carbon dioxide from the blood.
How Often the Test Is Done During Your Pregnancy. Your doctor may use the Doppler often to listen to your baby's heartbeat during routine checkups, starting at about 8 to 10 weeks. Handheld Dopplers will not work quite this early.
Ways That You Can Use at Home to Hear Your Baby's Heartbeat. Here are the top 4 safe and proven ways to hear the baby's heartbeat. A stethoscope â Not just any stethoscope but a high quality run. The better the quality the more likely you are to hear the baby between 18 and 20 weeks.