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Abstract
Coital activity is the primary behavioral determinant of fecundability, although data have been insufficient to test hypotheses about the impact of variations in coital frequency on fecundability, and ultimately fertility. This thesis uses data on coital activity collected by the Demographic and Health Survey (DHS) program in Brazil, Burundi, Ghana, and Sri Lanka, and simple models of fecundability which isolate the effect of coital behavior, to examine the validity of estimates of fecundability derived from survey data on coital activity. The analysis addresses questions about the quality of survey data on sexual activity, sources of variation in coital frequency, and how well models which estimate fecundability perform. The results contribute to our understanding of the possibilities and limitations of estimating fecundability from survey data on coital activity and ultimately the potential utility of data on coital frequency for expanding the analysis of the determinants of fertility differentials.
The principal conclusions of this thesis are, first, the data appears to be of sufficient quality to justify further analysis. Second, the multivariate analysis of the data provides additional evidence that women are aware of, and possibly manipulate, the complementary effects of coital behavior and contraceptive use for reducing the risk of pregnancy. Third, neither the information on coital frequency nor the data on the duration since last sexual intercourse emerge as clearly preferable for estimating fecundability.
Finally, the data on coital activity yielded estimates of fecundability controlling for age or marriage duration which are consistent with pregnancy rates for the three year period before the survey in Ghana and Sri Lanka. When no control on age or marriage duration is included in the analysis, however, the influence of physiological factors in determining fecundability dominates that of coital frequency. The limitations of the data and models for estimating fecundability from data on coital activity suggest that comparisons of fecundability estimated from coital activity data will not contribute to our knowledge of fertility differentials. Coital frequency provides additional information about fecundability for a narrow age range and only hints at the role coital frequency plays in differences in fecundability and fertility.
