About 50% of pregnant women experience some amount of vomiting or nausea associated with their pregnancy. Moms of multiples certainly aren’t exempt, but neither are they doomed to a double dose. Only about 15% of respondents in a poll on this site reported enhanced morning sickness symptoms as an indicator of their multiple pregnancies. Experiences vary widely — some do, some don’t.

Even though measuring large for gestational age may be a sign of a twin pregnancy, it can also happen during subsequent pregnancies of singletons. It is widely accepted that a second pregnancy shows sooner than a first pregnancy. So, it does not always indicate twins. If this is a first pregnancy it may be harder to determine by yourself without prior experience or your doctor’s advice. Also, your pre-pregnancy size will be a factor. A smaller framed, slim woman will almost always start showing any pregnancy sooner than a larger or heavier woman as a general rule. Coupling a large gestational age measurement with some of the other factors mentioned here would be a stronger indication of a twin pregnancy.

For various reasons, doctors may monitor HcG (human chorionic gonadotropin) levels. HcG is a hormone detectable in pregnant women’s blood or urine about 10 days post-conception; it increases at a rapid rate, peaking about 10 weeks into the pregnancy.

Most pregnant women don’t feel fetal movement until about 18 to 22 weeks. It is arguable that you would feel movement earlier than this if you are pregnant with twins. Although many women expecting twins claim to, there are a few factors to consider here. If this is a first pregnancy it may be difficult to determine if what you are feeling is indeed fetal movement. Also, a single fetus may be more active than usual causing stronger sensations in the womb. If this is a subsequent pregnancy you might have a sneaking suspicion or strong indication that that something is different with what you are feeling. I know one mother who, in her first pregnancy, did not feel her twin babies move at all until the 23rd week!

There is no better tried and true method of determining a twin pregnancy than having an ultrasound (also called a sonogram). On the ultrasound monitor your doctor or other professional can usually distinguish two fetuses and/or two heartbeats with ease. Indeed, many obstetricians perform an ultrasound as a definite confirmation of pregnancy at your first appointment.

Could you be having more than one? Check your symptoms against this list.