When to get an ultrasound
Most doctors recommend an ultrasound at around 20 weeks. During your second trimester ultrasound, you will be able to see the heartbeat and the movement of the baby. Your practitioner will determine if your baby is growing properly, as well as if the placenta is attached normally.
If you want to know the gender of your baby, this is the time to find out. By 20 weeks, your healthcare provider can usually determine the gender. Before you have a second trimester ultrasound, be sure to tell the technician and the doctor whether or not you want to know. Keep in mind that this isn't a foolproof method -- there's a chance that the ultrasound images can be misinterpreted.
During the ultrasound, your practitioner will determine whether the developing fetus, placenta, amniotic fluid and other structures look normal in appearance and are appropriate for the age of the baby. Keep in mind that if the results are not all normal, it does not necessarily mean you are having a miscarriage. Abnormal ultrasound results can identify multiple pregnancies, ectopic pregnancy, miscarriage, too much or too little amniotic fluid, problems with the placenta, issues with the baby's position and possible birth defects.
3D and 4D ultrasounds
To get a clearer picture of the baby in the womb, 3D and 4D ultrasounds are available at some facilities. While a standard ultrasound sends sound waves straight down, the 3D ultra sound sends the waves at various angles. Therefore, the resulting images feature width, height and depth -- a three dimensional picture of the fetus. With 4D ultrasounds, the images are in real time (rather than the delay associated with the computer constructed image in the 3D ultrasound). There is generally no medical benefit of a 3D or 4D ultrasound; therefore, these procedures are often considered elective. An elective 3D ultrasound may cost $300 or more, depending on the fees of the practice.