The 20 Week Ultrasound Isn't Really for Finding Out Baby's Sex

mom ultrasound.jpgOne of the reasons the second trimester is so exciting, aside from the fact that morning sickness usually starts to go away, is the excitement of the 20 week ultrasound. This is especially true if you are dying to find out your baby's sex. Here's the truth, though: the purpose of the routine 20 week ultrasound has nothing to do with looking at baby's genitalia!

What's It For?

The 20 week ultrasound, which may be scheduled routinely anywhere from 18-22 weeks of pregnancy, is a standard screening test that uses ultrasound to look at and measure your baby, your placenta, and your uterus for typical growth and placement. In other words, it's a scan for anything that could signal a health problem for you or your baby. If an abnormality is found, your doctor or midwife may suggest further tests to diagnose or rule out an issue. Ultimately, the goal is to be able to provide early intervention and support for health issues that are treatable. 

Is it Necessary?

While it has become standard and routine, it's important to know that the 20 week ultrasound is not required. Many people opt out of the ultrasound. Some studies have shown that the mid-pregnancy anatomy scan ultrasound does not improve outcomes. There can be false positives results in which an abnormality or potential problem is detected when in reality, there is nothing wrong and baby is perfectly healthy. There are also many abnormalities the anatomy scan ultrasound cannot detect. A healthy and "normal" 20 week ultrasound can provide false reassurance to parents who give birth to a child with a birth defect or other health issues. Of course, for parents who learn about a health problem through ultrasound and are then able to receive helpful treatment and intervention (whether in pregnancy or at birth), the procedure provides immeasurable benefits.

Is it Safe?

The decision to have an ultrasound is a personal one, and it is a procedure that you have the choice to accept or refuse. While it is considered by many a safe procedure, there are many unknowns about its long-term risks. The American College of Obstetricians and Gynecologists (ACOG) state:

Currently, there is no evidence that ultrasound is harmful to a developing fetus. No links have been found between ultrasound and birth defects, childhood cancer, or developmental problems later in life. However, it is possible that effects could be identified in the future. For this reason, it is recommended that ultrasound exams be performed only for medical reasons by qualified health care professionals. Casual use of ultrasound during pregnancy should be avoided.

I encourage you to learn more about the safety and risks of ultrasound and the many studies done on the topic in order to help inform your choice. There's an excellent research resource summary provided by Dr. Sarah Buckley, a family physician and renowned birth expert who specializes in the research on and practices in pregnancy, birth, and parenting.  

What Do they Look at?

So what do they look at in the 20 week ultrasound?? Glad you asked. Here's what your sonographer (person who conducts your ultrasound) is doing and looking for in the 30-40+ minutes you're together:

  • Baby's physical development
  • Major abnormalities in organs and body
  • Estimation of baby's gestational age 
  • Baby's position
  • Baby's movement
  • Baby's "breathing"
  • Baby's heart rate
  • Estimate of baby's size and weight (just an estimate!)
  • Estimate of the amount of amniotic fluid (just an estimate!)
  • Location of your placenta
  • Number of babies
  • And..... a peak at your baby's genitalia to reveal their sex, IF and only if they are in a good position to be able to see it, and if you want to know

Ultrasound, while it can have helpful benefits, is not an exact science. One of the biggest risks is that sometimes, medical interventions are performed when they were not truly necessary because ultrasound results showed a problem when there really wasn't one. On the other hand, ultrasound can catch true problems and result in care that improves outcomes for you and your baby. 

Now that you know that there is more to your 20 week ultrasound than finding out baby's sex and looking at their cute little profile, your decision to have one is up to you -- do your research and take a good childbirth class to learn more. Getting informed helps you to know which questions to ask and measures to take in order to make the healthiest choices for you and your baby.  



American College of Obstetricians and Gynecologists. FAQ: Ultrasound Exams. June 2017.

Dr. Sarah Buckley. Ultrasound Scans in Pregnancy - Your Questions Answered! July 2016.  

NHS. 20 Week Anomaly Scan.

Midwifery Today. Ultrasound: Weighing the Propaganda Against the Facts. 1999.

Parents. All About the 20 Week Ultrasound. 2015.

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