A: Dear Sara,
The second trimester ultrasound is a very exciting time for you and your partner—you are going to meet your baby! This scan is painless and takes approximately 30 minutes to perform. A technician will place a gel on your abdomen and slide a probe back and forth, surveying the baby. The ultrasound is a medical opportunity to look at the baby from head to toe. At many centers, they can check the baby's internal organs, spine, brain and bones with the scan.

Many times, the baby's gender can be determined with a high degree of certainty, although some babies are quite bashful and make it hard to establish their sex. If the ultrasound can't tell you the sex of your baby, it may be disappointing but not of medical significance. An ultrasound can help establish your due date within a two-week window, but that's not exactly the best way to figure the due date. Knowing the date of your last menstrual period or date of conception is a much better way to compute your baby's due date.