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To identify components of smoking-related increased perinatal mortality, detailed analyses of data from the Ontario Perinatal Mortality Study (50,000 births, 1,300 deaths, 1960-1961) measured the relationship of maternal smoking to birth weight, gestation, placental complications, and perinatal mortality. Cross-tabulations with other factors and multiple adjustment showed increases with amount smoked of birth weights less than 2500 gm, gestations less than 38 weeks, placenta previa, abruptio placentae, and perinatal mortality. These significant, smoking-related increases were independent of mother's height, weight, hospital status, age-parity group, birthplace, previous pregnancy history, weight gain, time of registration, and sex of child. Maternal smoking had the strongest effect on birthweight in the 8 factor regression, and birth less than 2500 gm increased directly with smoking level from 20% to 340% in 37 data subgroups. Births less than 38 weeks increased 20% and 50% and perinatal mortality increased 20% and 35% for less than 1 pack and 1 + pack smokers, respectively, adjusted for 7 other factors. Placental complications increased consistently with smoking level in all of 37 subgroups except for primiparous less than 1 pack smokers. Adjusted rates increased 25% and 92% for placenta previa, 23% and 86% for abruptions among smokers of less than 1 pack and 1 + packs, respectively. These complications carry high perinatal mortality risk, and account for one-third to one-half of the perinatal deaths attributable to maternal smoking.

Background and Purpose. Age-related loss of muscle mass and cardiovascular endurance can lead to impairments in muscle force production and cardiac function that, in turn, limit performance in activities essential to everyday living. The purposes of this study were: (1) to identify the “breakpoint” or threshold of maximal voluntary performance and performance in ordinary daily function (2) to evaluate the predictive validity of the threshold to identify the ability independently without self-reported functional limitation. Subjects and Methods. Men and women (N=192; mean age=76 years, SD=7 were recruited from single-family community dwellings or retiremet communities with multiple levels of care. Physical function was measured with the Continuous-Scale Physical Functional Performance Test (CS-PFP). Maximal voluntary performance measures included peak oxygen consumption (V̇) and isokinetic knee extensor torque (KET). Segmented linear regression models of the CS-PFP on the physical performance measures were used to determine the threshold values and their confidence intervals. A logistic regression model was used to evaluate the ability of the CS-PFP scores to identify those living independently and to further illustrate the concepts of threshold and physical reserve. Results. Threshold values identified for V̇O2peak (20 mL·kg−1·min−1) and KET (2.5 N·m/[kgom-1]) were associated with an average of CS-PFP scoe of 57 units. The threshold accurately predicted individuals reporting functional limitations. Discussion and Conclusion. The thresholds provide a mechanism for easily estimating an individual's physical reserve, predicting dependency in living status, and providing unbiased guidance for intervention in late-life independence.

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