ZYGOSITY AND PLACENTAL ANATOMY IN 15 CONSECUTIVE SETS OF SPONTANEOUSLY CONCEIVED TRIPLETS

Most triplets are trizygotic because they result from assisted reprodu ction, Prognosis is generally good, We analyzed 15 sets of triplets wh o were conceived spontaneously, Six sets were monozygotic, 7 were dizy gotic, and only 2 sets were trizygotic. Considered as 45 twin pairs, 2 5 pairs (56%) were monozygotic, Twenty percent of these twins died as a result of twin-twin transfusion, Spontaneously conceived triplets ha ve high risks compared with those resulting from assisted reproduction , These risks result from a high proportion of monozygotic embryos, ma ny of whom have monochorionic placentas with vascular anastomoses, cau sing twin-to-twin transfusion. (C) 1996 Wiley-Liss, Inc.