What are the main changes You Can Find on a 16 Week Ultrasound

16 week ultrasound

Many pregnant women are curious to know exactly what their developing baby looks like at 16 weeks. This is a week when many expectant parents have reached the second trimester of pregnancy, so it’s a good time to start taking an interest as well as imagining what your little one will look like as you finalize the nursery and buy those tiny outfits. There are some distinct differences between an 8-week ultrasound and a 16-week ultrasound, after all! So let’s take a deeper look into your baby’s development during these first months of life before birth!

Here are some of the changes You Can Find on a 16 Week Ultrasound

Development of Organs:

Week Ultrasound

16 weeks marks a turning point in fetal development as all major internal organs begin to form – including the heart which begins beating at around this time! Additionally, we see that the kidneys have begun producing urine and that mucus production has started as well (although this still needs some help from the amniotic fluid via swallowing). Though it’s not able to breathe on its own quite yet, your baby’s respiratory system is also beginning to develop as tiny buds sprout within its lungs…but it’s going to be a while before they’ll be called upon.

Development of Fingers and Toes:

Week Ultrasound

You may not notice this for a few more weeks, but during the 16-week ultrasound, you will start to see your baby’s toes and fingers become more defined. While at 8 weeks development is only in the very initial stages, by 16 weeks we can already make out five distinct digits on each hand and foot! Movement in these early developmental stages is so small that it’s often tough to find without proper equipment, however by 20-22 weeks most women can feel their child moving about inside them. This is also when the baby’s genitals are visible on an ultrasound image if you want to know whether you’re having a boy or a girl.

Development of Hair and Skin:

Over these next few weeks, you will notice your little one’s hair begin to sprout as the hair follicles develop deep within the skin. This is also when those tiny little eyelids form and begin closing and opening regularly, hiding and revealing those precious peepers beneath! More clearly defined lips and a nose are now present as well, but this too will take some time before it comes into focus on an ultrasound image.


The biggest change we see during this 16 Week Ultrasound is that overall size – babies at 16 weeks gestation typically fall in the length range of 2.6-2.9 inches (length from crown to rump) with an average weight of about 1.8 ounces!


As mentioned above, most women will be able to feel the movement during the 16-week ultrasound, but some won’t be able to until 20 weeks or even later. As early as this time you may also notice constant wiggling and poking of your baby’s umbilical cord – which can often feel like a “fluttering” inside of your belly just beneath your ribs! This is normal at any point throughout the day, but it does tend to become more active when you are resting or have had a recent meal…though it usually calms down again within 10-15 minutes.


From the 16-week ultrasound onward, be sure to make a note of your baby’s movements and any other changes you notice – as well as jotting down times when they tend to occur. This will help your doctor determine whether or not any potential issues are going on, especially if you can provide a detailed account from the very first days of the movement.

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