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Frequency of Triplets and Triplet Zygosity Types among U.S. Births, 1964
Published online by Cambridge University Press: 01 August 2014
Abstract
The frequency of triplets in the U.S. white population may have reached an all-time low around 1964, at 78 sets per million deliveries. One-fourth of those were monozygotic as estimated by the difference method, or 18% by Bulmer's theoretical model. By 1983 the frequency of triplets had nearly doubled, the increase presumably occurring in dizygotic and trizygotic types. In Belgium most triplet pregnancies now result from artificial induction of ovulation, which is expected to occur mainly in older mothers. In the U.S., however, triplets have increased as much in young mothers as in older mothers, proportionally. This age distribution of the increase may be partly explained by a decrease in parity in older mothers since 1964.
- Type
- Research Article
- Information
- Acta geneticae medicae et gemellologiae: twin research , Volume 37 , Issue 3-4 , October 1988 , pp. 299 - 306
- Copyright
- Copyright © The International Society for Twin Studies 1988
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