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Am I carrying twins?
Q: Everyone is saying that the size of my stomach is really big. I am five months pregnant. How would I know if I'm having twins?
A: Dear Nicola,

You touched on a couple of very important pregnancy issues. First, that when we are pregnant we are subject to unsolicited, well-intentioned comments from people all around us. As pregnant women, we are already sensitive to the myriad of changes in our own bodies. As our belly grows, our pregnancy becomes more public. I am always amazed at how easy it is for other people, even strangers, to bestow their opinions on us, not realizing how sensitive we might be to their comments. When someone tells you that you are “really big,” you can’t help but wonder if they are right. When I had my first pregnancy, I remember hearing two different comments the same day: one person thought I was too big, and the other thought I was too small. I decided on that day that I would not pay attention to such comments.

The fact is, it is very hard to judge whether a pregnant woman is growing appropriately when she is standing up fully dressed. When I examine a pregnant woman, I must measure the size of her uterus while she is lying down with her abdomen unclothed. When you stand up, your belly size reflects how loose your stomach muscles are, how tall you are and therefore how much space your baby has to grow “inside” versus protrude “outside,” how much fatty tissue your body carries, and how full your bladder and intestines are. When you lie down for an exam, it is easier to isolate the size of the uterus. A uterus that measures larger than expected could indicate a large fetus, a uterus with extra amniotic fluid, a uterus with fibroids (benign muscle growths on the uterine wall), a fetus that is older than initially thought, and sometimes, twins.

The only way to positively know if you are carrying twins is to have an ultrasound. This is a machine that uses sound waves with a transducer to give a visual picture of your uterus and what it contains. If you had an ultrasound from a qualified provider at any point in your pregnancy, and you were told that you do not have twins, then it is most likely you have a singleton pregnancy (only one fetus). Most American health care providers will request an ultrasound exam at least once during your pregnancy. Often this is done between 16 and 20 weeks, when the fetus has organs that can be well visualized. If your uterus measures large at other times during the pregnancy, additional ultrasound exams could be helpful to check on the size of your baby and the quantity of fluid that surrounds the baby at that time.
Laura E. Stachel M.D. Obstetrician & Gynecologist