title: Twin pairs, smoking in pregnancy and perinatal mortality.
abstract: Twins born in the province of Quebec during the first six months of 1972 were ascertained by reviewing all live births and perinatal death certificates. A total of 852 twins, constituting 426 pairs, were included in the study. Smoking habits of the mother during pregnancy were recorded at the hospital of birth for 88.5% of the pairs. The risk of at least one perinatal death was significantly higher for twin pairs born to smoking mothers. The Mantel-Haenszel test statistic controlling for sex of pairs, parity (0,1+), maternal age (< 25,25+ years) and years of schooling was 4.224 (p = 0.04). The standardized risk ratio for smoking versus nonsmoking mothers that a pair will have at least one death was 1.77 (95% confidence limits: 1.03-3.04). As expected, the relative risk of perinatal death associated with smoking appears to be higher for twins than for singletons.
mesh_terms: D000328:Adult; D004522:Educational Status; D005260:Female; D005313:Fetal Death; D005865:Gestational Age; D006801:Humans; D007226:Infant Mortality; D007231:Infant, Newborn; D008297:Male; D008423:Maternal Age; D010298:Parity; D011247:Pregnancy; D011792:Quebec; D012306:Risk; D012907:Smoking; D014427:Twins