From Death to Birth Mortality Decline and Reproductive Change (1998) / Chapter Skim
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8 Fertility Response to Infant and Child Mortality in Africa with Special Reference to Cameroon
8 Fertility Response to Infant and Child Mortality in Africa with Special Reference to Cameroon
Pages 254-315
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From page 254... ...
These replacement effects provide insights into the contributions that declining infant and child mortality rates in Cameroon have had on the concurrent fertility reduction. The estimated parameters integrate aspects of life- cycle fertility that have previously been studied in isolation of each other: completed fertility, childlessness, and interbirth intervals.
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From page 255... ...
Table 8-1 presents an overview of published work that has attempted to measure the fertility response to infant and child mortality, using aggregate or individual data. Aggregate Level Studies based on aggregate data have one important advantage over individual data: the potential for measuring the overall implications of improvements in child survival for fertility and population growth.
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From page 256... ...
survey with no a' births; me of childre Cantrelle 1940-1972 12 sub-Saharan Retrospective loo, 2Q1 TFR, GF} et al., 1978 African countriesb and prospective 2Qo surveys Cantrelle 1962-1968 Niakhar, rural Longitudinal Child death Mean birt and Leridon, Senegal study of 8,456 interval 1971 live births Coale, 1966 1940-1962 13 sub-Saharan Retrospective loo, 2Q1 TFR African countriesC surveys Cochrane 1977-1978 Lesotho (1977) and Retrospective Child death Birth inte: and Zachariah, Kenya (1977- 1978)
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From page 257... ...
death Birth interval Multivariate Yes n.a. Yes analysis (individual data)
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From page 258... ...
) Characteristics of the Study Year/Period Measure of Data Source Collection Country/Strata Study Design Mortality Fertility Folta and Deck, No date Zimbabwe Participant Child death Fertility 1988 observation and following in-depth interviews a child de of 124 women Heer and Wu, 1966 Urban Morocco Area probability Number of the Number o 1978 sample of first three life births currently married children that subsequer women under age survived either to the 50 who had to age 10 or to third experienced 3 or the time of more live births interview Jensen, 1993 1988, 1990 Bungoma and Cross-sectional Number of CEB Kwale, Kenya interviews with children 132 women aged deceased 18-78 Jensen, 1996 1988-1989 Kenya, Zimbabwe, DHS surveys Infant & Hazard of Botswana child death following birth Livenais, 1984 1973, Rural Mossi, Cross-sectional loo TFR 1978 Burkina-Faso surveys Okojie, 1991 1985 Bendel state, Retrospective Proportion CEB Nigeria survey of 1,895 of surviving ever-married children women aged 15-50 Sembajwe, 1981 1973 Western Nigeria Retrospective Proportion of CEB survey children dead NOTES: TFR, total fertility rate; GFR, general fertility rate; loo, infant mortality rate; 2Q1 = second-year mortality rate; 2Qo, first two years mortality rate; Ado, first five years mortality rate; CEB, children ever born; n.a., not applicable;WFS, World Fertility Survey; DHS, Demographic and Health Survey; LDC, less-developed countries.
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From page 259... ...
er of the Number of Multiple Yes Unclear Yes tree life births classification n that subsequent analysis ed either to the (individual and 10 or to third aggregate data) he of few er of CEB Multiple Yes ma.
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From page 260... ...
. The individual-level studies reviewed in Table 8-1 consistently show that the death of an infant leads to a shorter interval between that birth and the next, and therefore provides a clear indication that, at the individual level, there is a significant fertility response to child loss.
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From page 261... ...
find strong evidence of fertility response to child loss. This raises important population policy and substantive questions regarding the weight to give to the evidence of mortality effects on fertility at the aggregate level versus individual level in Africa more generally.
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From page 262... ...
The overwhelming evidence is that short birth intervals have strong effects on infant and child mortality; such a result has been reported in Cameroon (Kuate Defo and Palloni, 1996) and elsewhere (for a review, see Hobcraft, 1994~.
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From page 263... ...
In this case we group these two physiological and volitional replacement mechanisms of increased risks following conception under the term "replacement behavior." Moreover, it has been shown that, in many parts of sub-Saharan Africa where prolonged breastfeeding is prescribed and sexual intercourse during lactation is forbidden, the physiological effect is culturally built into behavior patterns (Ware, 1977~. For the longterm replacement effects in the subsequent intervals, significant effects of the death of a child of parity i on the hazards of conceiving children of parity i + 2, i + 3, i + 4, and so forth cannot be ascribed to a biological/physiological mechanism but only to a volitional (behavioral)
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From page 264... ...
In this chapter, I test three hypotheses regarding the fertility responses to child death: Hypothesis 1: A child death has both instantaneous (short-term) and lagged (long-term)
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From page 265... ...
points out that in populations where conscious limitation of family size is negligibly important, completed family size can be viewed simply as the cumulative outcome of uncorrelated birth intervals spanning a woman's reproductive life. In such populations, it is legitimate to regard intervals and completed family size as simultaneously determined: hence interval effects translate immediately into fertility effects.
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From page 266... ...
These data also provide the opportunity to relate the length of interbirth intervals to the survival status of previous children. Obviously, any variations between women in interbirth intervals that can be attributed to differences in child death experience give only a partial measure of the replacement effect
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From page 267... ...
Number of months/100 spent in the current spell Length of the first conception interval, measured in months/100 Length of the second conception interval, measured in months/100 Length of the third conception interval, measured in months/100 Length of the fourth conception interval, measured in months/100 Length of the fifth conception interval, measured in months/100 Length of the sixth conception interval, measured in months/100 Series of time-varying dummy variables capturing the sequencing of an infant death and couple's future reproductive behavior A dummy time-varying variable = 1 if a mother lost her child who opens the birth-to-conception interval [i, i + 1) in his first year of life and at least 1 month before the conception of the index child (i.e., the child of parity i + 1)
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From page 268... ...
In addition, those aspects of the intentional replacement effect that influence timing will be mixed with the physiological effect, particularly in populations where family planning is practiced. FORMULATION AND ESTIMATION OF FERTILITY RESPONSE TO CHILD LOSS I formulate and implement a multistate duration hazard model as a framework for estimation of the effects of child mortality on fertility (for details, see the Appendix)
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From page 269... ...
. My modeling strategy of the effects of infant death on fertility starts with the premise that fertility is usually indicated by birth spacing, parity, and maternal age at maternity.
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From page 270... ...
2I also experimented with alternative specifications of the fertility response to changes in infant and child mortality by formulating hazards models assuming both the piecewise exponential (proportional hazard) and a Gompertz hazard model for the risk of a subsequent conception starting with the first birth, but none of my conclusions was altered with these alternative specifications.
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From page 271... ...
This is because little attention appears to have been paid in studies of the fertility response to child loss, to the possibility that such fertility behavior may be linked to achieved parity. Replacement behavior is detected by the inclusion of a series of measures of experienced child mortality.
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From page 272... ...
The time-invariant exogenous variables include maternal education, ethnicity, religion, and employment before first marriage. These variables were selected for analyses because they have been shown to covary with child survival and reproductive behavior in Cameroon (Kuate Defo, 1996; Kuate Defo and Palloni, 1996; Larsen, 1994, 1995~.
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From page 273... ...
obstetric methods used by traditional birth attendants, especially in the eastern and northern provinces; and (2) traditions affecting the initiation, type, and duration of breastfeeding, particularly in the northern province where inappropriate weaning practices have been identified as the major cause of malnutrition (Kuate Defo, 1996~.
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From page 274... ...
, I would expect women who were employed before their first marriage to differ from others with respect to fertility and fertility responses to an eventual child death. Sex Composition of Living Children The sex of living children may influence the effects of infant mortality on fertility if the couple wants more boys or more girls.
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From page 275... ...
Restricting the analyses to the intervals, say beginning 2 and 10 years before the survey, may reduce recall error for intervals that began very long ago and reduce selection biases for very recent intervals, but this may lead to a downward bias in conception rates (the key dependent variable here) since the inclusion, for example, of the closed birth intervals beginning as long as 10 years before the survey may overrepresent women with low fecundity (Guz and Hobcraft, 1991)
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From page 276... ...
Second, the social norm in most African societies is that when a woman's own daughter begins bearing children, her status of grandmother may preclude her bearing children so that she can oversee the rearing of her grandchildren (Caldwell and Caldwell, 1981; Acsadi et al., 1990~. The extent to which such norms might be violated and the limiting behavior reversible if a child death should occur is unknown and deserves investigation.
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From page 277... ...
deaths of the first, second, third, and fourth parity children on the length of subsequent birth intervals, controlling for maternal parity. It shows the median birth intervals according to the survival status of the child initiating the interval at the time of the conception of the index child or at the time of censoring, as well as the reduction in the time elapsed to the time of the conception of the next birth that is associated with the death of the child who starts the interval.
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From page 278... ...
In the top half of the table I examine the parity-specific pattern of variation in median birth interval associated with an infant death, whereas in the lower half of the table I examine the pattern of variation in median birth interval ascribed to an infant death by selected comparable characteristics in the two data sets. The overall pattern is that the reduction in median birth-to-conception interval for a child who dies in the first year of life compared with a child who survives through the first year of life is 5 months (or 17 percent reduction)
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From page 279... ...
-(8) 25 25 24 6 4 5 9 6 7 23 25 23 7 4 5 7 5 5 27 24 24 5 5 5 8 2 5 26 25 26 7 4 5 4 3 3 25 25 24 6 3 5 8 5 6 24 19 6 3 5 7 4 6 25 28 8 2 5 5 2 2 26 24 6 3 4 9 5 6 23 24 6 6 7 8 6 7 24 24 5 4 5 9 4 7 25 24 7 4 5 8 7 7 27 25 3 1 2 6 3 6 These results consistently show that the reduction in median birth-to-conception interval associated with an infant death in the two data sets is larger in the neonatal period than in the postneonatal period, the difference being 3 months in the more recent data set (the CDHS data)
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From page 280... ...
The short-term mortality effects are termed "replacement behavior" effects and for them I distinguish between the physiological and volitional replacement effects. The longterm mortality effects evoke mainly volitional replacement effects.
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From page 281... ...
Such a measure of the fertility response to a child death in its first year of life is a mixture of volitional replacement effects and physiological effects having to do with the cessation of breastfeeding. Mortality effects attributable to volitional replacement effects alone are presented below.
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From page 282... ...
Because women with a child death are likely to have had greater exposure to the risk of conception than those without, exposure must be controlled in the analysis as done here (for further detail, see the Appendix)
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From page 283... ...
The relative risks of a subsequent conception caused by a child death appear to change rather trivially for all transitions, with a small reduction of 6 percent in the relative risk of conceiving the second birth (from 1.83 to 1.77 in the CWFS, and from 1.80 to 1.74 in the CDHS) reflecting the highest impact of controlling for measured covariates that, not surprisingly, affect fertility independently of the mortality effects.
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From page 284... ...
* hazard upon infant death (0.047)
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From page 285... ...
bMonth before the conception of the index child. CTen-year period preceding survey.
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From page 286... ...
Thus, the sex of the previous children appears to affect subsequent fertility behavior, but this has no bearing on the mortality effects of the child who opens the index birth-to-conception interval (i.e., the birth-to-conception interval under study)
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From page 287... ...
.3 In Table 8-6 I consider the possibility that woman-specific unobserved characteristics may influence the robustness of the replacement effects. Although there are significant unobserved characteristics of the woman affecting her conception risks, these unobservables are empirically unimportant in explaining the fertility responses to child loss in both the CWFS and the CDHS.
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From page 288... ...
* hazard upon infant death (0.047)
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From page 289... ...
(0.662) 7,293 aDeath of the immediately preceding child in the first year of life and 1 month before the conception of the index child.
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From page 290... ...
The estimated replacement effects remain statistically significant for all transitions and for both data sets. Net of the measured covariates, the implied stopping probabilities associated with parity-specific unobserved heterogeneity show no consistent pattern and essentially fluctuate from one parity to the next, but the magnitude of the differential diminishes at higher birth orders in both data sets.
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From page 291... ...
A common approach in previous studies has been to compare the additional children born subsequent to a specific parity between women who have experienced a child death up until that point and those who had not. In Tables 8-9 and
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From page 292... ...
* hazard upon infant death (0.032)
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From page 293... ...
bone month before the conception of the index child. CTen-year period preceding the survey.
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From page 294... ...
* upon infant death (CMMl)
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From page 295... ...
Similarly, the CDHS data suggest that the death of the third child significantly reduces the risks of conceiving the fifth birth. Because the more widely spaced pattern is the pattern of childbearing that most couples choose in most African societies because of postpartum taboos and practices and longer breastfeeding durations, it will be easier to replace a child death with an additional birth through a compression of interbirth intervals.
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From page 296... ...
296 FERTILITY RESPONSE IN AFRICA WITH SPECIAL REFERENCE TO CAMEROON TABLE 8-9 Six-Equation Joint Hazard Model of Long-Term Mortality Effects on Fertility: The Child Who Opens the Birth-to-Conception Interval [i, i + 1) Dies at Least 1 Month Before the Conception of Children of Higher Parities (CMM2)
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From page 297... ...
BARTHELEMY KUATE DEFO Effects , i + 1)
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From page 298... ...
. Effects of the First Child's Death on Long-Term Fertility Behavior Tables 8-9 and 8-10 show the effects of the survival status of preceding siblings on the hazards of conception of the subsequent births.
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From page 299... ...
may have a large effect on both short- and long-term fertility responses, far exceeding the simple replacement effect. Therefore, the fertility behavior of a woman may be more influenced over time by the sense of "insurance" derived from the survival status of her first birth rather than a set target family size.
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From page 300... ...
Parity-Specific Effects of the Fertility Response to Child Loss As noted above, most previous studies of the effects of child mortality on fertility have assumed that those effects were the same across parities. Essentially, such studies preclude the reproductive life-cycle perspective in assessing the effects of child death on the hazards of closing the birth interval.
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From page 301... ...
The effects of the death of the first birth on fertility in the future (transitions from the third birth to the conception of the fourth birth, from the fourth birth to the conception of the fifth birth, and from the fifth birth to the conception of the sixth birth) are indicative of strong lagged fertility responses to child death, in addition to robust instantaneous fertility responses to the first child loss (transition from the first birth to the conception of the second birth)
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From page 302... ...
I had hypothesized that the behavioral replacement effect could be accomplished by compressing interbirth intervals, as my results across parities show. Furthermore, I note as expected that the empirical implication of the behavioral replacement mechanism is a lagged fertility response to changes in mortality, as shown by the robust findings regarding the mortality effects of the first and second births on future reproductive behavior.
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From page 303... ...
APPENDIX: HAZARD MODELS AS A REDUCED-FORM APPROACH TO DYNAMIC (LIFE-CYCLE) MODELS OF FERTILITY RESPONSE TO CHILD MORTALITY This appendix presents my implementation of a system of hazard models for the estimation of the effects of mortality on times to conception.
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From page 304... ...
I pay attention to the timing of first birth and the spacing between births, and I argue that the spacing of births is influenced by the past and recent infant mortality experience of couples. Thus, since biological constraints would prevent most couples from having all desired births at once, it is of interest to ask, once the first birth occurs, what mechanisms lead to longer or shorter birth intervals?
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From page 305... ...
In my specification, and following Heckman's formulation in continuous-time of the system of hazards approach to fertility behavior (Heckman and Singer, 1985; Heckman and Walker, 1991) , I implement a continuous-time approach to the system of hazard models of fertility response to infant and child mortality.
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From page 306... ...
One important feature of this system of hazard model formulation is that it provides a natural way to allow time-varying covariates to affect the timing of the
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From page 307... ...
Accounting for them is often necessary so as to produce estimates that isolate genuine behavioral effects of covariates (such as child mortality) on fertility, and the existence of unobservables provides a motivation and interpretation for the presence of statistically significant lagged birth intervals in fitted survival rates for birth parities beyond the first parity (Heckman and Walker, 1991~.
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From page 308... ...
study in Sweden where third births are not common and fourth births are rare) , making estimation of the correlation in unobservables between interbirth intervals impossible; this is in contrast to the situation in sub-Saharan African countries (and in Cameroon in particular)
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From page 309... ...
who estimate a birth process with duration dependence modeled as a three-point spline and assume a parametric distribution of the unobserved heterogeneity, which excludes parityspecific unobserved heterogeneity. Basically, they take the random effect to be person-specific and time invariant.
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From page 310... ...
Thus, the fertility responses to a child death may not be only a function of other measured characteristics of the woman, but may also be related to unmeasured characteristics associated with each woman and each parity of a particular woman. This system of hazards formulation in continuous time suggests natural restrictions on how the covariates enter the model.
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From page 311... ...
Ben-Porath, Y 1978 Fertility response to child mortality: Microdata from Israel.
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From page 312... ...
Heer, D., and J Wu 1978 Effects in rural Taiwan and urban Morocco: Combining individual and aggregate data.
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From page 313... ...
Kuate Defo, B 1996 Areal and socioeconomic differentials in infant and child mortality in Cameroon.
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From page 314... ...
1991 Fertility response to child survival in Nigeria: An analysis of microdata from Bendel State. Research in Population Economics 7:93-112.
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From page 315... ...
1992 Ware, H 1977 The relationship between infant mortality and fertility: Replacement and insurance effects.
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