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Chapter 7 Multiple Gestations
Chelsea Ward, MD
❍ What percentage of all pregnancies are twins and higher order multiple gestations?
3.3% of all live births in the United States, about 3% worldwide.
❍ How has the incidence of multiple gestations changed?
At least 65% increase in twins and 500% increase in triplets and higher order births since 1980.
❍ What is the risk of multiple gestation with infertility treatments?
Up to 25% assisted reproductive technology (ART) pregnancies result in multiples.
❍ What is the incidence of multiple pregnancies with the use of clomiphene citrate?
8% with <1% triplets or higher order gestations.
❍ What is the incidence of multiple pregnancies with the use of gonadotropin therapy?
25% with approximately 1% to 2% triplets or higher order gestations.
❍ What percentage of multiple infants births from ART represent triplets or higher order gestations?
4% to 5% of all live births.
❍ What are the different etiologies of multiple fetuses?
Fertilization of two separate ova (dizygotic, 70%) or from a single fertilized ovum that subsequently divides
(monozygotic, 30%).
❍ What is superfecundation?
Fertilization of two ova within a short period of time but not at the same coitus, nor necessarily the sperm from
the same male.