Twinning rate in spontaneous abortions.
An unselected series of spontaneous abortions and their mothers were karyotyped with Q-bands to obtain a frequency of twin conceptions lost during the first trimester. Among 661 spontaneous abortions, 15 twin pairs were identified including two sets of conjoined twins. Analysis of Q-band variants permitted the exclusion of cases with two cell lines that could be attributed to maternal contamination or mosaicism. The twinning rate among spontaneous abortions was 1/44 compared with 1/103 live births and stillbirths in the Ontario population. If Weinberg's differential method is applied to these data, the frequency would be as high as 1/30 under the assumption that the incidence of monozygotic twins among abortions is the same as that for live births.
D000022:Abortion, Spontaneous; D000328:Adult; D002869:Chromosome Aberrations; D002871:Chromosome Banding; D005260:Female; D006801:Humans; D007621:Karyotyping; D011247:Pregnancy; D011272:Pregnancy, Multiple; D014428:Twins, Conjoined