Maternal Smoking During Pregnancy and Sudden Infant Death Using the National Maternal and Infant Health Survey: A Case-Case Study

We utilized data from the National Maternal and Infant Health Survey (NMHIS) to analyze the risk of SIDS and other infant deaths among women who smoke during pregnancy adjusting for potentially modifiable risk factors such as secondhand smoke exposure and breastfeeding. The following variables were assessed with respect to risk for SIDS and other infant deaths: smoking exposure, level of education, infant and maternal age, infant and maternal birthweight, maternal BMI, gender, secondhand smoke exposure, breast feeding, prenatal vitamins, WIC, multiple gestation, sleep apnea monitor prescription, sleep apnea incidents and maternal alcohol use. Univariate analysis and multivariate logistic regression were performed to identify variables significantly associated with the odds of mortality from SIDS. Analysis utilized weighted estimates using SUDAAN 9.0.0 to adjust for design effects. A p-value <0.01 was considered statistically significant. Women who smoked during pregnancy were 1.83 times more likely to give birth to an infant that died from SIDS versus some other cause of death, OR (95%) = 1.83(1.33, 2.51). Other Race infants and Black infants were more likely to suffer SIDS mortality than White infants, but the result was not significant in the final model. Other modifiable risk factors, such as secondhand smoke exposure and breast feeding, were not significant predictors of SIDS mortality. Independent of sociodemographic variables and other potential risk factors for SIDS death, maternal smoking was associated with an increased risk of SIDS death versus other death. This study highlights the importance of screening all pregnant women for tobacco use and emphasizes the importance of smoking cessation to decrease the risk of infant death from SIDS.

Three-Dimensional Modeling of Shallow Shear-Wave Velocities for Las Vegas, Nevada, Using Sediment Type

A three-dimensional model of near-surface shear-wave velocity in the deep alluvial basin underlying the metropolitan area of Las Vegas, Nevada （USA）, is being developed for earthquake site response projections. The velocity dataset, which includes 230 measurements, is interpolated across the model using depth-dependent correlations of velocity with sediment type. The sediment-type database contains more than 1 400 well and borehole logs. Sediment sequences reported in logs are assigned to one of four units. A characteristic shear-wave velocity profile is developed for each unit by analyzing closely spaced pairs of velocity profiles and well or borehole logs. The resulting velocity model exhibits reasonable values and patterns, although it does not explicitly honor the measured shear-wave velocity profiles. Site response investigations that applied a preliminary version of the velocity model support a two-zone ground-shaking hazard model for the valley. Areas in which clay predominates in the upper 30 m are predicted to have stronger ground motions than the rest of the basin.