Final Report (PDF, 2132K) - Measure DHS

3. FERTILITY3.1 Fertility Data in the ODHSThis chapter presents fertility indices describing different aspects of childbearing among womenin Ondo State. First, statistics depicting fertility levels during the period 1981-86 are presented--totalfertility rates and age-specific fertility rates. Then, statistics on the total number of children ever born arepresented by age group. Finally, statistics on the median age at first birth are presented by age group andbackground characteristics.Data on the childbearing experience of respondents were collected in several ways. First, womenwere asked their aggregate fertility in a series of six questions: the number of sons and daughters that liveat home, the number of sons and daughters that live elsewhere and the number that had died. Second,data pertaining to specific births were collected with a truncated birth history for the six year period from1981 to the survey date (i.e., respondents were asked to report their most recent live birth and eachpreceding live birth extending back in time to the birth immediately preceding 1981). For all reportedbirths, information was obtained on month and year of birth, sex, name, survival status and, if dead, age atdeath. Third, respondents were asked the month and year of their first birth, if that birth occurred prior tothe births enumerated in the truncated birth history.The truncated birth history is an established procedure for the collection of retrospective fertilitydata. This approach is designed to provide data suitable for the estimation of fertility levels for a periodimmediately prior to a survey--in the case of the ODHS, for the period 1981-86. As with anyretrospective procedure, the truncated birth history can suffer from event underreporting (in particular, theunderreporting of children who die in early infancy) and misreporting of the dates of birth. The formerproblem is potentially serious for infant mortality estimation, while the latter problem primarily concernsfertility estimation. For example, when the truncated birth history approach is used, misreported birthdates can transfer events across the reference boundaries and bias period-specific fertility rates. In orderto limit the effect of such misreporting, fertility data should be collected for a longer retrospective periodthan that for which fertility rates are actually calculated. In the ODHS, fertility data were collected for allbirths since 1981 and for the immediately preceding birth, while estimation of fertility rates is limited tothe period since 1981.3.2 Levels, Differentials and Trends in FertilityEstimates of fertility levels are presented in terms of the total fertility rate (TFR) and the meannumber of children ever born. The "1"1~1¢. is a period fertility index which indicates the number of childrenthat a woman would have if she experienced throughout her lifetime the age-specific fertility rates of aparticular time period. The mean number of children ever born is a retrospective fertility index whichindicates the actual number of children women have had. Fertility trends can be determined bycomparing the "lrK for recent time periods with the number of children ever bom to women aged 40-49.In Table 3.1, TFRs for women up to age 45 are presented for two three-year calendar periodspreceding the survey (1981-83 and 1984-86) and one five-year period preceding the survey (which,because the fieldwork for the survey was primarily done in late 1986, approximates 1982-86). The pairof three-year estimates suggest a substantial decline in fertility from 6.3 children per woman in 1981-83to 5.6 children per woman in 1984-86; a decline of 0.7 children per woman. However, caution must beexercised in interpreting these three-year estimates. In the ODHS, interviewers were trained to probe for19