Although an article published in the British Medical Journal states that 95 percent of multiple pregnancies are diagnosed before delivery, families are occasionally surprised by the appearance of two or more babies at the time of delivery. There are only a few definite signs of multiple pregnancy; other signs are presumptive, but not proof.
Ultrasound
If there are two or more fetuses seen on an ultrasound, it's a definite sign of a multiple pregnancy. However, some women who thought they were having twins have been surprised by the appearance of a third baby, because one fetus may not be visible behind the other two, unless the technician is really looking for a third.
In higher order multiples, which is any pregnancy of triplets or more, babies are more easily missed, because of the constant fetal motion and the difficulties of keeping so many little arms and legs straight. According to the Geneva Foundation for Medical Education and Research (GFMER), multiples can be diagnosed as early as seven weeks, when separate fetal bodies can be identified.
Multiple Heartbeats
If two or more heartbeats are heard, it's a sure sign of multiple pregnancy. However, just hearing heartbeats in two different locations doesn't mean there's more than one. It takes two people listening and independently checking to make sure the beats differ from each other and from Mom by at least 10 beats per minute, according to the GFMER.
HCG Levels and Effects
Blood levels of hCG (human chorionic gonadotropin), the pregnancy hormone, may be higher than normal in multiples, but this isn't a definite sign of multiples. It does, however, indicate a need for further evaluation, according to Dr. Alexandra Matias. Extreme fatigue, more than is normal in pregnancy and severe nausea and vomiting are possible signs of multiple pregnancy produced by the higher than normal hCG level.
Uterine Measurement
A uterus that seems to be growing faster than normal, measuring large for dates as measured by medical personnel and "showing" early may be a sign of multiple pregnancy, according to Dr. Matias. However, women who have had previous pregnancies often show sooner than those in their first pregnancy. Growth of fibroids, benign tumors in the uterus, may also cause the uterus to expand more quickly than normal.
Alpha Fetoprotein Levels
Alpha fetoprotein (AFP) is a blood test done to check for proteins that are elevated in certain genetic abnormalities, like Down Syndrome. In cases of multiples, because two or more fetuses are producing AFP, the levels will be elevated, according to the University of Virginia Health system.
