Dizygotic twinning, marital stage and status and coital rates

Wh, James

doi:10.1080/03014468100005171

Cited by 19 publications

(14 citation statements)

References 19 publications

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“…And-except in one important respect-these events may all be presumed to have promotional effects on coital rates, too. The exception is that the coital rates of young (under 20) unmarried (coitally active) women are substantially less than those of young married women [6]. Now in England and Wales, the DZ twinning rate of unmarried women aged less than 20 is lower than the comparable rate for married women [6].…”

Section: Jamesmentioning

confidence: 88%

Dizygotic Twinning, Birth Order, Female Psychology, and Coital Rates

James¹

1982

Acta genet. med. gemellol.: twin res.

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It is well established that the dizygotic (DZ) twinning rate increases with maternal age until about age 38 and thereafter declines, and that within each maternal age category, it increases (apparently indefinitely) with parity [5]. Interpretation of this increase with parity is not immediately clear. One may formulate two hypotheses, one or both of which may be true.Hypothesis 1: Twin-prone women are more fertile than other women and therefore they form a progressively increasing proportion of the mothers at each birth rank and/or Hypothesis 2: Each birth somehow adds an increment to a woman's probability of bearing a DZ twin pair at her next pregnancy.Allen [1] tested the latter hypothesis in the following way. For a group of sibships all of the same size, and all of which contained a pair of DZ twins, he considered only those pregnancies occurring in a given limited age range, e.g., 25-29. The test consisted in observing whether the twin maternities were then related to birth order within this age range. He found that they were. Accordingly, he drew the inference that the second hypothesis was true.This led him [2] to question the evidence which had seemed to support hypothesis 1. Among the sorts of evidence he considered were the prompt postmarital conceptions [4,9] and prompt postwar conceptions [3,8] of DZ twins. He found that within the reproductive histories of women bearing DZ twins, the conception delays leading to first-born DZ twin pairs were less than those leading to first-born singletons. Though he admits that the difference was not significant, he writes: "It probably means that prompt conception is not a constant characteristic of parents of twins; their chance of early conception need not be any greater than that of other couples." It seems to me that (even if the difference were significant) the argument is misleading. The contrast that would be interesting is between the conception delays preceding first-born singletons in DZ twin sibships and the first conception delays in other sibships. If there were no difference between them, then Allen's suggestion would be vindicated.In support of his case, Allen writes [2]: "It seems as if the marriage event itself promotes twinning; and so does return of husbands from war, or an illicit love affair." 0001-5660/82/3101-02-0119S01.00

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Section: Jamesmentioning

confidence: 88%

Dizygotic Twinning, Birth Order, Female Psychology, and Coital Rates

James¹

1982

Acta genet. med. gemellol.: twin res.

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“…However, they are classified as unmarried. James (1981) , 1962-1966, and noted that the illegitimate DZ twinning rate is lower than the legitimate rate at the lowest maternal age (15-19) and is higher only at the higher maternal ages, resulting in a steeper slope. Also MacGillivray et al (1988) have observed a decreasing effect of marital status on the twinning rates.…”

Section: Statistical Inference Problems With Demographic Macrodatamentioning

confidence: 99%

Temporal Differences in the Regional Twinning Rates in Sweden after 1750

Fellman¹,

Eriksson

2003

Twin Res

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“…A variety of factors have been associated with dizygotic twinning. These factors include advanced maternal age, parity, increased maternal height and weight, use of fertility drugs and contraceptives, social class membership, birth order, specific blood group characteristics, conceptions occurring after periods of sexual abstinence, and available nutritional supply (Nylander, 1975;Corney, Seedburgh, Thompson, Campbell, MacGillivray, & Timlin, 1981;Clark & Martin, 1982;Wyshak, Honeyman, Flannery, & Beck, 1983;James, 1983;Garza-Chapa, Escobar, Cerda, & Leal-Garza, 1984;Elwood, 1985). Ethnic differences in the DZ twinning rate have been associated with differences in many of these characteristics (Nylander, 1975).…”

Section: Factors Responsible For Twinningmentioning

confidence: 99%

The Importance of Twin Studies for Individual Differences Research

Segal

1990

Jour of Counseling & Develop

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Twin research designs and methods are valuable tools for examining genetic and environmental influences on behavioral and medical characteristics. A review of the biological bases of twinning and descriptions of 10 research designs are presented. Findings from a selected sampling of twin studies of learning disabilities, personality and temperament, attitudes, psychopathology, and social behavior are summarized. The findings are discussed with special reference to the activities of mental health practitioners and counselors.

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Dizygotic twinning, marital stage and status and coital rates

Cited by 19 publications

References 19 publications

Dizygotic Twinning, Birth Order, Female Psychology, and Coital Rates

Dizygotic Twinning, Birth Order, Female Psychology, and Coital Rates

Temporal Differences in the Regional Twinning Rates in Sweden after 1750

The Importance of Twin Studies for Individual Differences Research

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