A comparison of breast-feeding data from the National Surveys of Family Growth and the Ross Laboratories Mothers Surveys.

This study compares rates of breast feeding reported in the National Surveys of Family Growth with those from the Ross Laboratories Mothers Surveys. Both surveys have documented rates of breast feeding over the last 30 or more years. Despite differences in survey methodology, both surveys document similar long-term trends in breast feeding. The similarities of rates in breast feeding also are evident across several maternal sociodemographic characteristics. We conclude that both surveys produce reliable and useful estimates of breast feeding.

Contraceptive use at first premarital intercourse: United States, 1965-1988.

The proportion of U.S. women who used a contraceptive method at their first premarital intercourse rose from 47 percent in 1975-1979 to 65 percent in 1983-1988. Overall, and among non-Hispanic white women, this change resulted entirely from an increase in the use of condoms by their partners. The proportion of whites who used a condom at first premarital intercourse, for example, increased from 24 percent to 45 percent. Among blacks, condom use at first intercourse increased from 24 percent to 32 percent during that period, and pill use rose from 15 percent to 23 percent. Among all women, the method most often used at first intercourse during every period in the study was the condom, followed by the pill and withdrawal. The proportion of women using a method at first premarital intercourse varies strikingly according to individual characteristics. Among the various demographic subgroups, the proportion who use a method varies from 32 percent of Hispanic women to 68 percent of Jewish women. Whites are more likely to use a method than are blacks, and fundamentalist Prostestants are less likely to use a method than are other Protestants or Catholics. The proportion using a method is higher among women whose mothers completed high school than among those whose mothers did not. In addition, the proportion rises with age at first intercourse. Multiple logistic regression showed that the independent effects of Hispanic origin, Jewish or fundamentalist Protestant religious affiliation and the education of a woman's mother are large and significant.(ABSTRACT TRUNCATED AT 250 WORDS)

Spatial patterns in the fruiting bodies of the cellular slime mold Polysphondylium pallidum.

During morphogenesis in the slime mold Polysphondylium pallidum cell masses are periodically pinched off from the base of the developing sorogen. These masses round up and differentiate into secondary sorogens, which become radially ordered arrays of secondary fruiting bodies called whorls. Here we describe the morphogenesis of P. pallidum and characterize the spacing of whorls along the central stalk of the fruiting body and the spacing of sorocarps within whorls. We find both are highly regular. We propose that the linear spacing of whorls can be accounted for satisfactorily by a model that views the periodic release of cell masses from the base of the developing sorogen as the consequence of an imbalance between forces that orient amoebae toward the tip of the culminating sorogen, and cohesive forces between randomly moving cells in the basal region of the sorogen, which act as a retarding force. The orderly arrangement of fruiting bodies within whorls can be explained most easily by models that employ short-range activation and lateral inhibition.