Elevated HcG Levels
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. Twins may produce an elevated level of HcG. However, the standard HcG level for twins also falls within the normal range for singletons.
Abnormal AFP Test Results
AFP (Alphafetoprotein) screening is a blood test performed on pregnant mothers during the second trimester. Also known as maternal serum screening or triple marker screen, it is used to identify increased risks of certain birth defects. A twin pregnancy can produce an usually high -- or "positive -- result.
Measuring Large for Gestational Age
Throughout the pregnancy, the doctor or midwife may measure the height of the uterine fundus (from the top of the pubic bone to the top of the uterus) as a way of indicating gestational age. A twin or multiple pregnancy may causes the mother's uterus to expand beyond the range of a single pregnancy. However, other factors may also increase the measurements.
Weight Gain
Just as a multiple pregnancy may cause a mother to measure large, it may also result in an increased weight gain. How much weight a woman gains can vary depending on her height, body type and how much she weighed pre-pregnancy. Increased or rapid weight gain more than likely reflects eating choices rather than twins; generally, mothers of twins only gain about 10 lbs. more than singleton mothers.
Excessive Morning Sickness
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.
Early/Frequent Fetal Movement
Feeling a baby -- or babies -- move inside the womb is one of the most thrilling aspects of pregnancy. Although many moms of multiples do experience more frequent or earlier fetal movement, there is considerable disagreement among medical professionals on the subject. For some women, recognizable feelings of movement occur earlier in subsequent pregnancies, whether there is one baby or more.
Extreme Fatigue
This is the most commonly reported complaint during pregnancy with multiples. Sleepiness, lethargy and exhaustion during the first trimester can be enhanced because the body is working overtime to nurture more than one baby. In some cases, the fatigue can be attributed to other factors (work, stress, poor nutrition, having other children), but it can also be an indication of multiples.
History/Hunches
While the other items in this list refer to some kind of visible evidence -- exaggerated symptoms, abnormal test results, etc. -- we can't disregard the power of a mother's intuition. A family history of multiples, or a powerful hunch can be convincing indicators. Follow up with your doctor about these feelings.