The end of reproductive life in mothers of twins: epidemiologic analysis of a large data base.
A case-control study was conducted on the termination of menstrual life on mothers of twins. It involves a much larger data base and finer analyses, and makes use of the same methodology of a previous study. The time interval between the twin and the last confinement proved to be shorter in twin-bearing mothers than in a matched set of controls with singletons only after blocking of the effect of birth order, and despite the similarity of maternal age at delivery and confinements numbers. Mothers of like-sex twins only appeared to terminate reproductive life earlier than controls. The separate study of maternal age at twin confinement shows that the earlier the twin birth the shorter the menstrual life thereafter. Both like-sex twin births and early maternal age at delivery of a twin pair have the same shortening effect on subsequent menstrual life without clear evidence of additivity of effects as if both occurrences were alternatives with similar biological effects. Comparison of the results of the current study with those of our earlier analysis shows consistency on above results. However, the current study could not reproduce previous results on the role of unlike-sex twins or late maternal age at delivery on time to last confinement; yet, they cannot be discarded. It is suggested that increased power of interaction analyses and tighter matching of controls with respect to sex might improve the conclusions of subsequent studies.
Philippe
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Department of Social and Preventive Medicine, Faculty of Medicine, University of Montreal, Canada.
D000328:Adult; D005260:Female; D006801:Humans; D008423:Maternal Age; D008593:Menopause; D008875:Middle Aged; D011247:Pregnancy; D011272:Pregnancy, Multiple; D011792:Quebec; D012737:Sex Factors; D013997:Time Factors