Ultrasound has been used for more than 30 years and is not known to cause any harm to pregnant women or her baby. That said, ultrasound should not be routinely used unless your doctor has a specific medical reason for doing so.
How accurate is ultrasound in dating a pregnancy?
Ultrasound is extremely accurate when used during the first trimester. Measuring the baby's crown to rump length at this stage can pinpoint a baby's gestational age within 3-5 days while similar measurements taken during the other two trimesters take relatively longer. Therefore the first trimester is the preferred time to date a pregnancy.
What are the other reasons for performing a first trimester ultrasound?
- Your doctor may order a first trimester ultrasound to
- Pinpoint the location of the gestational sac (the developing fetus is contained within this sac), something that can be useful in
- diagnosing an ectopic pregnancy.
- Look for evidence of an embryo
- Check for a fetal heartbeat
- Find out if you are carrying more than one baby
- Examine the uterus for structural abnormalities or other problems that could pose problems during your pregnancy