Mary B. Meyer

Maternal smoking, pregnancy complications, and perinatal mortality

Analysis of data from the Ontario Perinatal Mortality Study has shown that perinatal mortality increases directly with the level of maternal smoking during pregnancy. Increases in smoking level are associated with increases in the frequency of early fetal deaths and of neonatal deaths due to premature delivery. These deaths in turn are associated with smoking-related increases in the incidence of bleeding during pregnancy, abruptio placentae, placenta previa, and premature and prolonged rupture of the membranes.

Low birth weight and neonatal mortality rate related to maternal smoking and socioeconomic status

Abstract Neonatal deaths occurring over a 10 year period among infants born to nonsmoking and smoking mothers enumerated in a nonofficial census of Washington County, Maryland, were compared with a sample of live births from the same population. In addition to maternal smoking, low birth weight, and neonatal mortality rate, a considerable number of demographic and socioeconomic characteristics were studied. Smoking mothers consistently had a higher proportion of small babies regardless of almost all other characteristics. Neonatal mortality rate was approximately 40 per cent higher among infants born to smokers than among those born to nonsmokers. The excess among smokers was most marked among families who ranked low on socioeconomic characteristics. The hypothesis is advanced that hypoxia resulting from increased maternal and fetal carboxyhemoglobin levels is the factor responsible for both the decrease in birth weight and the increase in neonatal mortality rate among infants born to smoking mothers.

How does maternal smoking affect birth weight and maternal weight gain? Evidence from the Ontario Perinatal Mortality Study.

A large data set was used to examine the possibility that maternal smoking during pregnancy causes low birth weights by reducing maternal appetite, eating, and weight gain. As always, birth weight distributions shifted downward as maternal smoking level increased. Maternal weight gain distributions, on the other hand, were the same for smokers and nonsmokers. Within each level of maternal weight gain, from less than five pounds to over 40 pounds, the more the mothers smoked the greater was the percentage of neonates weighing less than 2,500 grams. This evidence supports a direct effect of maternal smoking on birth weight, possibly due to the hypoxic effects of carbon monoxide, rather than one mediated through eating. Efforts to prevent or reduce smoking should have greater benefits for mother and child than would efforts to increase food intake among pregnant women who smoke.

Respiratory effects of household exposures to tobacco smoke and gas cooking.

The records of 1,724 residents of Washington County, Maryland, who had participated in 2 studies of respiratory symptoms and ventilatory function were analyzed to evaluate the effects of exposures at home to tobacco smoke generated by other members of their households and to fumes from the use of gas as a cooking fuel. Currently smoking subjects showed the highest frequency of respiratory symptoms and impaired ventilatory function; former smokers showed a lower frequency of these findings; and persons who had never smoked had the lowest prevalence of abnormal respiratory findings. The presence of a smoker in the household other than the subject was not associated with the frequency of respiratory symptoms, and only suggestively associated with evidence of impaired ventilatory function. The use of gas for cooking was related to an increased frequency of respiratory symptoms and impaired ventilatory function among men, being most marked among men who had never smoked. There was no evidence that cooking with gas was harmful to women.

Respiratory effects of household exposures to tobacco smoke and gas cooking on nonsmokers

The records of 708 nonsmoking white adult residents of Washington County, MD, who had participated in two of respiratory symptoms were analyzed to evaluate the effects of exposure at home to two potential sources of indoor air pollution: cigarette smoking by other household members, and use of gas as a cooking fuel. After adjustment for the effects of age, sex, socioeconomic level, occupational exposure to dust, and years of residence in household, the presence of one or more smokers in the household was only suggestively associated with a higher frequency of chronic phlegm and impaired ventilatory function defined as FEV1 < 80% predicted. The use for cooking was associated with a significantly increased frequency of chronic cough and a significantly greater percentage with impaired ventilatory function as measured both by FEV1 < 80% predicted and by FEV1/FVC < 70%.