Gestational trophoblastic disease in New Zealand, 1980-1986

During the period 1980 to 1986, inclusive, 350 cases of gestational trophoblastic disease were recorded within New Zealand; of these cases nearly 70% were reported to a Register established to obtain epidemiological information. Clinical information obtained with the notifications revealed no difference in incidence of gestational trophoblastic disease among the 3 main ethnic groups which make up the New Zealand population; the uterine fundus was recorded as being large for dates in only 26%; the most common clinical presentation was as a threatened abortion; 7% of the cases were diagnosed at either routine ultrasound examination or at termination of pregnancy, there having been no suspicions prior to that procedure. A review of histological material obtained following notification suggested that the histological diagnosis of trophoblastic disease could not be substantiated in 14.7% of cases. During the period under review, therefore, there were 299 cases of trophoblastic disease (all but 2 of which were hydatidiform mole) and 447,667 pregnancies giving an incidence of 1 case of trophoblastic disease per 1,497 pregnancies.