Twins can be one of two types: identical, or fraternal (fruh-TER-nal). If a single fertilized egg splits, the result is identical twins. When two eggs are produced in the same month, and fertilized by two different sperm, the result is fraternal twins. It's recommended that women expecting twins increase their daily caloric (kah-LORE-ick) intake by three hundred calories, and consider taking a protein and calcium supplement. If pregnant with twins, your weight gain should only exceed your normal weight by 30 to 45 pounds, depending on your pre-pregnancy weight. Vitamin and mineral supplements should be taken daily, especially iron, which prevents anemia. Twins are considered high-risk pregnancies; therefore, you may be required to visit the obstetrician more often for prenatal visits and ultrasound exams. Some potential complications of a twin birth include pre-term labor, a condition in which uterine contractions begin before 37 weeks of gestation; and Pre-eclampsia (PREE-ee-CLAMP-see-a) which is pregnancy-induced high blood pressure, often accompanied by rapid weight gain and swelling. Finally, a condition known as Intrauterine (in-truh-YOO-ter-in) Growth Retardation can inhibit the growth of the fetuses in the uterus. I-U-G-R can affect both fetuses equally, or one fetus more than the other. If the weight between the fetuses differs by more than 15 to 25 percent, your doctor may require more frequent ultrasounds to monitor their growth. Some cities have organizations and clinics that can help you adapt to the new situation and prepare you for your new role. For more information regarding twins, contact a health care provider.