Identical twins come from a single fertilized egg that divides in half.
- Thirty percent of twins are identical.
- Identical twins are the same sex and have the same genetic makeup.
- They may share amniotic sacs and placentas, or be separate.
Fraternal twins come from two eggs fertilized by two sperm.
- Although they are born at the same time, fraternal twins are no more alike than other brothers and sisters born to the same parents.
- Inside the mother, fraternal twins are surrounded by separate sacs. They have separate placentas, although sometimes the placentas may grow together.
- Fraternal twins are more likely to be born to:
- Women 35 and over
- Women who have already had twins
- Women who become pregnant soon after stopping birth control pills
- Women for whom twins run in the family
Risks from carrying twins
- Preterm delivery due to early labor or early rupture of the membranes
- Preeclampsia (high blood pressure, protein in the urine, and/or swelling)
- Gestational diabetes
- Poor fetal growth
- Increased blood loss with delivery
- Cesarean section, if one of the twins is not coming out headfirst
- Because twin pregnancies are more likely to have complications, you may be more likely to need bedrest or hospitalization.
Birth and beyond
- Breastfeeding is usually possible with twins, and the body adapts by making more milk.
- There are special pillows and techniques for breastfeeding twins.
- Dartmouth-Hitchcock has lactation consultants who can help you with any breastfeeding questions you may have.
- There are local support groups for mothers of twins.
- "Having Twins And More: A Parent's Guide to Multiple Pregnancy, Birth, and Early Childhood" by Elizabeth Noble
- National Organization of Mothers of Twins Clubs, Inc.
- Sidelines, a resource for high-risk mothers and their families
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