When Can You Tell How Many Children Are in the Womb?

Ultrasound Technology

• Before ultrasound technology, a woman often wouldn't find out she was having multiples until she delivered the babies. In more modern times, ultrasounds are used regularly, and you'll probably have more than one during the course of your pregnancy. Many obstetricians perform a vaginal ultrasound to confirm a pregnancy, and many others do an ultrasound in the first few months so you can see the heartbeat. Ultrasounds also are used if your doctor suspects that there is a problem with your pregnancy, or to track the growth and development of the baby or babies.

Time Table

• A vaginal ultrasound can be done in the first few days of your pregnancy, but it usually shows the doctor only an egg sac, which proves that you are, indeed. pregnant. Your doctor might order an ultrasound if your uterus is larger than average or if your belly is measuring larger than it should for how far along your pregnancy is, according to MayoClinic.com. An ultrasound of your belly between your sixth and eighth weeks of pregnancy can show you accurately how many babies you're carrying. If your doctor holds off on the ultrasound until your second trimester, you'll likely learn about the multiples after your 12th week, according to Robin Elise Weiss, author of "The Complete Illustrated Pregnancy Companion."

Other Methods for Detecting Multiples

• While an ultrasound isn't the only way to detect twins or multiples, it's the most common and accurate. Many times, the presence of multiples is found when a doctor hears more than one distinct heartbeat, which usually occurs toward the end of the first trimester. According to Weiss, elevated numbers on certain blood tests also can indicate the presence of more than one baby. If you haven't learned that you're pregnant with multiples yet, these blood tests routinely are done during the second trimester.

Physical Signs

• Excessive weight gain or severe nausea might indicate that you have more than one baby in your womb. These symptoms alone don't necessarily indicate that you're pregnant with multiples, but your doctor might consider an ultrasound, especially if multiples run in either side of your baby's family. Later in your pregnancy, feeling as if your baby is moving all over the place might indicate that there's more than one baby in there. Feeling movement earlier than normal also might suggest that you're pregnant with multiples. Extreme fatigue is another possible symptom, but it can occur with just one baby, too.