Pregnancy outcome and prenatal diagnosis of sex chromosome abnormalities in Hawaii, 1986-1999.

Sex chromosome abnormalities such as Turner syndrome, Klinefelter syndrome, triple X syndrome, and 47,XYY can be prenatally diagnosed and electively terminated. This investigation examined the pattern of pregnancy outcome of prenatally and postnatally diagnosed sex chromosome abnormalities in Hawaii during 1986-1999 and calculated prenatal diagnosis and subsequent elective termination rates for various factors. Data were obtained from a statewide population-based birth defects registry. The study included 205 detected sex chromosome abnormality cases of which 93 (45%) were live births, 18 (9%) late fetal deaths, 37 (18%) early fetal deaths, and 57 (28%) elective terminations. Pregnancy outcome distribution varied by type of sex chromosome abnormality. Prenatal diagnosis was reported for 132 (64%) of the cases, of which 46 (35%) were subsequently electively terminated. Eleven cases were elective terminations where the sex chromosome abnormality was diagnosed after delivery. Elective termination rates subsequent to prenatal diagnosis differed by sex chromosome abnormality, being highest for 45,X (54%), followed by 47,XXY (46%), 47,XYY (29%), and 47,XXX (17%). Although prenatal diagnosis rates increased significantly over the time period (P = 0.006), the subsequent elective termination rate declined slightly, albeit the trend was not statistically significant (P = 0.440). The prenatal diagnosis rate was highest for the 35-39-year maternal age group, although this age group did not have subsequent elective termination rates higher than other maternal age groups. Pregnancy outcome distribution and prenatal diagnosis and subsequent elective termination of sex chromosome abnormalities appeared to depend on the type of sex chromosome abnormality, year of delivery, and maternal age.