• The only way to know for sure if you’re expecting twins is to identify two separate heartbeats. They can be detected by abdominal ultrasound in your fourth month or by vaginal ultrasound as early as seven or eight weeks.
• Finding the right doctor is important. Women carrying multiples need to make sure their pregnancy is being treated as a multiple pregnancy, not a single pregnancy, and that their doctor is aware of the special issues concerning multiples.
• With twins, your need for calcium is even more important.
• Your due date may be somewhat up in the air. Twins often are born prematurely because their combined weight may speed the onset of labour.
• Your weight gain will be greater. For example, will be between 35 and 45 pounds rather than the 25 to 35 pounds for a single birth.

Your chances of having twins

• Your chances of having twins are about 1 in 80!
• History of twins: Once you have a set of fraternal twins, you're twice as likely to have another set in future pregnancies.
• Heredity: If twins run in your family, you're more likely to have them. Your partner's family history doesn't appear to affect your odds of having twins.
• Age: The older you are, the higher your chances of having fraternal twins or higher multiples.
• Nutrition: Being well nourished increases your chances of having twins and being mal-nourished decreases your chances.
• Number of pregnancies: The more pregnancies you've had, the greater your chances of having twins. In fact, by your fourth or fifth pregnancy, your likelihood of having twins is four times higher than it was for your first pregnancy.
• Race: Twins are more common than average in African Americans and less common in Hispanics and Asians.