A fetal ultrasound can be done at any point during pregnancy. Your health care provider might use a fetal ultrasound to:
- Confirm the pregnancy and its location. Some embryos develop in the fallopian tube instead of in the uterus. A fetal ultrasound can help your health care provider detect a tubal (ectopic) pregnancy.
- Determine your baby's gestational age. Knowing the baby's age can help your health care provider determine your due date and track various milestones throughout your pregnancy.
- Confirm the number of babies. If your health care provider suspects a multiple pregnancy, an ultrasound might be done to confirm the number of babies.
- Evaluate your baby's growth. Your health care provider can use ultrasound to determine whether your baby is growing at a normal rate. Ultrasound can be used to monitor your baby's movement, breathing and heart rate as well.
- Study the placenta and amniotic fluid levels. The placenta provides your baby with vital nutrients and oxygen-rich blood. Too much or too little amniotic fluid — the fluid that surrounds the baby in the uterus during pregnancy — or complications with the placenta need special attention.
- Identify birth defects. An ultrasound can help your health care provider detect various birth defects.
- Investigate signs or symptoms. If you're bleeding or having other complications, an ultrasound might help your health care provider determine the cause.
- Perform other prenatal tests. Your health care provider might use ultrasound to guide needle placement during certain prenatal tests, such as amniocentesis or chorionic villus sampling.
- Determine fetal position before delivery. A C-section might be needed if the baby is in an abnormal position.
If your health care provider doesn't suggest a fetal ultrasound but you'd like the reassurance the exam can provide, share your wishes as you work together to determine what's best for you and your baby.