Other twins are fraternal. They develop from two different eggs and do not have identical genes. They may or may not be the same sex. Your health care provider may use ultrasound during the first trimester to try to determine whether twins are identical. He or she will check for one or two amniotic sacs or placentas.
Doctors can determine most accurately if twins are identical with DNA testing.
Your provider may suspect you are pregnant with more than one baby if your uterus seems larger than expected or if he or she hears more than one heartbeat. The earlier you and your provider know that you are having more than one baby, the better it is for you and the babies. There is a greater chance the babies will be born early and will be smaller than single babies. You and your health care provider will discuss what you can do to reduce the risks for your babies. You will talk about your diet and your need for vitamins and iron and enough rest.