At week 15 the baby is now about 4 inches long and about 3 ounces in weight. On a 3D ultrasound it is possible to see the gender of the baby, is it a boy or a girl. It is still challenging to see the gender on conventional ultrasounds at 15 weeks, although it is possible. For conventional ultrasounds, the best time to see the gender as well as the rest of the anatomy is around 18-19 weeks.
3D/4D ultrasounds are perfectly safe for the baby. There are very few medical reasons to use this technology but they can provide fun pictures and video for the family. There are many companies that will do private ultrasounds for obtaining pictures, videos, and determine the baby’s gender. These are safe and can be fun. The price has been coming down as more competition has entered the market, so shop around. It is important to understand that this is not a medical ultrasound It is being down to provide photographically pleasing pictures. You will need to pay for this service outside of your insurance. 15 weeks is a great time to tell gender on 3D ultrasound. In my opinion, the best pictures are around week 26 as the baby has some fat under the skin at that gestational age and looks like a little baby rather than an alien.
Week 15 is when the baby starts to have practice breathing motion. The baby is not really breathing as it is living inside a water environment. But it is moving amniotic fluid in and out of the lungs. This is very important for two reasons. The practice breathing helps develop and exercise the muscles responsible for breathing. When the baby is born it will be important to have these muscles developed and ready to breath. The moving of the amniotic fluid into and out of the lungs is necessary for lung development. This movement of fluid into and out of the lungs is thought to help stimulate the development of the lung tissues.
15 weeks is also the earliest time that second trimester blood screening can be done. We generally recommend waiting until 16 weeks in our office as we have found that it reduces some of the false positive results or tests that cannot be run do to improper timing.