A probability distribution for time of first conception
Singh, K.K.; Srivastava, U.
Genus 47(3-4): 159-169
1991
ISSN/ISBN: 0016-6987 PMID: 12285500 DOI: 10.2307/29789068Document Number: 324316
The period between marriage and 1st conception has served for the estimation of fertility parameters, especially fecundability. The objective was to develop a truncated probability model for the time of the 1st conception since marriage assuming that all females were exposed to the risk of conception during a specified period of time after marriage. The observed distribution of time from return marriage (RM) to 1st live birth conception was taken from a survey conducted in 1978 by Banaras Hindu University, Varanasi, India on a stratified random sample of all 3514 households from 19 villages. Data relating to age at marriage and return marriage or the actual conjugal life of a female, intervals between RM and 1st birth and consecutive births, and age of female at different orders of births were collected from each married woman below 50 years of age. Nonattainment of menarche and presence of adolescent sterility during the early part of the reproductive period depend upon age at RM, and the effect of these factors on the married life of a female is more with a lower age at RM. Therefore, the data of the 1st birth interval with respect to low age at RM only were subject to the analysis. However, when several biological factors, social customs (the traditional intercourse taboos) were accounted for, the estimates of the 1983 1st birth interval data probability model developed by Mishra were the lower limits as opposed to the upper limits of this model. In India some factors reduce coital frequency and consequently the estimate of fecundability such as the traditional intercourse taboos; joint family system more observance of traditional taboos; occupancy of separate space by male and females at night; and the abstinence within marriage, i.e., temporary separation of husband and wife.