Is It Twins? 10 Signs That You're Having Twins/Multiples

4. 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.

5. 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.

6. 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.