19. How can I tell if my multiples are identical or fraternal?
To determine zygosity, your doctor may look (around 12-18 weeks gestation) for separate and distinct sacs as well as separate and distinct placentas for each fetus. Unfortunately, this method can only confirm identical multiples when more than one infant shares an amniotic sac and/or sometimes a placenta. Because identical multiples can also appear separately, mono-zygosity cannot be ruled out if separate sacs and placentas are seen.
Unless zygosity is confirmed through a shared amniotic sac or placenta (not just a merged placenta which can sometimes happen with fraternal multiples), the only definitive way to know zygosity is to test the placentas at the time of delivery or to DNA test each child after birth.
way parents of identical multiples can meet other families of identical
multiples is through the
MOST Family Support Forums.
The Mom 2 Many website offers more detailed information on zygosity testing.
MOST also offers our book Expecting Multiples: A Comprehensive Guide covering a variety of topics related to pregnancy and delivery of higher-order multiples.
Copyright MOST 2005 Updated 9/14/10