Two ultrasounds are usually performed during pregnancy. The first between weeks 11 and 14, the second between weeks 18 and 21. Depending on your health and the development of your pregnancy, you may get more than two scans [1]. Scheduling will vary depending on where you live.
Why do you need an ultrasound in the first trimester?
At 11–14 weeks of pregnancy, an ultrasound is performed as part of your prenatal care to determine whether the baby is developing as expected. It will also help identify any signs of abnormalities [2].
What exactly is an ultrasound?
During an ultrasound, your doctor checks your uterus to make sure there are no issues that may interfere with your pregnancy. At the same time, your doctor will look for signs of chromosomal abnormalities in the baby, their heartbeat, head size, and bone lengths. The thickness of the nuchal fold — the tissue at the back of the baby's neck — is also measured to determine the risk of Down syndrome. If your doctor has any doubts, they will have you undergo additional examinations [3].
Why is the screening carried out at this time?
At 11 weeks, it is easier to confirm the length of the pregnancy and determine if you are having twins. It’s also the best time to consider the external signs of chromosomal abnormalities, if any. Before week 10, the baby is still too small, and after week 14, your choices and available screenings are more limited if something abnormal appears [4, 5].
I was given a referral for an ultrasound outside my doctor’s office. Does this mean something is wrong?
Not all OBGYN offices are equipped to perform detailed ultrasounds. So don’t worry if you are sent somewhere else to get your ultrasound. Talk to your doctor about it if you need reassurance.
Do I need to prepare for the procedure?
The first-trimester ultrasound does not require special preparation. Your doctor may advise you not to eat certain foods, such as those that cause gas, or they may recommend you drink more water than usual [5].
Should I get a 3D ultrasound?
Since its invention more than 20 years ago, the question of the 3D ultrasound remains undefined. This procedure does not provide any medical advantages, especially considering that most technicians undergo training in 2D only. However, there are no safety concerns regarding 3D ultrasounds [6].
