Kelly, M.D., M. P.
Results: A vanishing twin occurred in one third of the twin pregnancies. Forty-six percent of these losses occurred after fetal heart activity had been established.
Conclusions: Vanishing twin phenomenon occurred in a large proportion of twin pregnancies in this infertility population. Fetal heart activity was not a reliable predictor of continuing fetal viability in early twin gestation. Vanishing twin conceptions were characterized by a slower rate of rise of hCG than normally progressing twin pregnancies.
Fertil Steril 56:211, 1991
The twin resorption rate of 320.5% in this study is consistent with previous reports.
References: Levis, S: Ultrasonic assessment of the high rate of human multiple pregnancy in the first trimester. J Clin Ultrasound 4:3, 1976.