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September 16, 1939


JAMA. 1939;113(12):1133. doi:10.1001/jama.1939.02800370049016

Single ovum twinning appears to be mainly a chance phenomenon. Double ovum twinning apparently is influenced by heredity, age and parity. In the first forty years of the obstetric department of Johns Hopkins Hospital, 521 cases of twinning occurred in the combined hospital and home delivery services, or about one set of twins in every eighty pregnancies, counting both viable pregnancies and the abortions. This ratio nearly agrees with that of the whole birth registration area of the United States. In a comprehensive study of this experience, Guttmacher1 has published two papers and anticipates several others. Two methods are commonly employed to differentiate single from double ovum twins: first, the study of the twins themselves; second, the study of the placental relations. The diagnosis by the first method is best made when the twins are between 2 and 4 years of age. Numerous physical criteria must be satisfied. To