of TTTS cases may be very conservative. Although infertility treatments have increased the rate of multiple birth, they have not appreciably diluted the expected incidence of identical twins. Studies show a higher rate of identical twins (up to 20 times with IVF) using these treatments versus spontaneous pregnancy rates. One Australian study, however, noted an occurrence of only 1 in 4,170 pregnancies, or 1 in 58 twin gestations. This distinction could be partly explained by the "hidden mortality" associated with MC multifetal pregnancies—instances lost due to premature rupture of membrane (PROM) or intrauterine fetal demise before a thorough diagnosis of TTTS can be made. History TTTS was first described by a German obstetrician, Friedrich Schatz, in 1875. Once defined by neonatal parameters—differences in birth weight and cord hemoglobin at the time of delivery—TTTS is now defined differently. Today, it is known that discordant fetal weights will most likely be a late manifestation, and fetal hemoglobin through cordocentesis is often equivalent in the twin pair even in severe TTTS. In art A painting known as the De Wikkelkinderen (The Swaddled Children), from 1617, is thought to represent a depiction of TTTS. The drawing shows twins that appear to be identical, but one is pale, while the other is red. Analysis of the family histories of the owners of the painting suggests that the twins did not survive to adulthood, although whether that is due to TTTS is uncertain. See also The Twin to Twin Transfusion Syndrome Foundation Twin anemia-polycythemia sequence Vanishing twin Unequal placental sharing References External links Connecting the World to Fight TTTS, including TAPS, SIUGR and TRAP Pathology of pregnancy, childbirth and the puerperium Syndromes Twin Transfusion medicine