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MATERNAL AND ENVIRONMENTAL FACTORS AFFECTING TWIN BIRTHS IN CANADIAN CITIES
Author(s) -
Elwood J. M.
Publication year - 1978
Publication title -
bjog: an international journal of obstetrics and gynaecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.157
H-Index - 164
eISSN - 1471-0528
pISSN - 1470-0328
DOI - 10.1111/j.1471-0528.1978.tb14893.x
Subject(s) - geography , demography , sociology
Summary Details of 4972 pairs of twins born to mothers resident in 14 large Canadian cities in the years 1952, 1957, 1962, and 1967 were compared to those of a random sample of 4969 single births. Both dizygotic and monozygotic twinning rates, derived by Weinberg's formula, showed increases with both maternal age and with the number of previous livebirths. Dizygotic twinning rates also showed a seasonal variation with an October maximum. Twinning rates were lower in Oriental women, but did not vary between other ethnic groups, or by city of residence, legitimacy, paternal age or maternal history of stillbirths. The data were kindly supplied by Mr N. Tompkins and the staff of Statistics Canada, and computer programming was performed by Mr K. Johnson.