An elevated HcG level, extreme fatigue, exaggerated morning sickness, rapid weight gain and an enlarged uterus are signs of a twin pregnancy, according to Pregnancy.org. In some cases, the only sign of a multiple pregnancy is a woman's intuition that she is carrying more than one baby, notes Family Education.
A woman who is carrying twins might report feeling very hungry. She might also report feeling fetal kicks and other movements early in the pregnancy. In some cases, twins might be suspected if a midwife, nurse or doctor hears more than one fetal heartbeat on a Doppler device. The incidence of a twin pregnancy is usually confirmed by doing an ultrasound, according to About.com.