Secular Changes in the Twinning Rate in Denmark 1931 to 1977
- 1 September 1980
- journal article
- research article
- Published by SAGE Publications in Scandinavian Journal of Social Medicine
- Vol. 8 (3), 89-94
- https://doi.org/10.1177/140349488000800302
Abstract
The present study examines secular changes in the rate of twinning in Denmark during the period 1931–77. Total twinning (i.e., mono- and dizygotic twinning combined) declined from a crude rate of 15.0 twin births per 1000 deliveries in 1931 to 9.6 twin births per 1000 deliveries at the end of the period. After direct adjustment for maternal age and parity (between the years 1935 and 1965), a 22% decline in total twinning rates was noted. Estimates of the rates of dizygotic twinning over the same period, again adjusted for maternal age and parity, show a decline of 29%. Thus there is evidence of a real decline in twinning, independent of the effects of changing patterns of maternal age and parity. These findings are consistent with reports of a general decline in twinning rates from a number of other countries. The interpretation of such secular changes is a matter for speculation.This publication has 4 references indexed in Scilit:
- SPERM COUNT DEPRESSION IN PESTICIDE APPLICATORS EXPOSED TO DIBROMOCHLOROPROPANEAmerican Journal of Epidemiology, 1979
- Twinning Frequencies in Baden-Wurttemberg According to Maternal Age and Parity from 1955 to 1972Acta geneticae medicae et gemellologiae, 1976
- The Secular Decline in Dizygotic Twinning Rates in ItalyActa geneticae medicae et gemellologiae, 1975
- PITUITARY GONADOTROPHIN AND DIZYGOTIC TWINNINGThe Lancet, 1964