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OCR for page 12
Hypotheses About Reproductive Patterns
and Women's and Children's Health
In developing countries, where resources are scarce, health services are poor
and not readily available, and infectious diseases are common, it is difficult to
maintain good health. Although the primary causes of poor health in such an
environment are often beyond the control of individual families (at least in the
short run), there are ways in which they can act to reduce the risk of illness and
death. Choosing to limit fertility, to delay the onset of childbearing, to space
births, and to breastfeed are among the actions that may reduce the risk of illness
and death to women and children.
The central objective of this report is to assess the effects of particular repro-
ductive patterns for the health of women and children. Of course, reproductive
patterns are not a direct cause of death, in the way hemorrhage or infectious
diseases are, but rather they may be associated with conditions leading to death.
The chapter begins by examining hypotheses about the direct effects of reproduc-
tive patterns, first on women's health, then on children's health. By direct effects
we mean the biological and behavioral mechanisms through which a change in
childbearing patterns might affect women's and children's health directly. Next,
we discuss hypothesized indirect effects of changes in reproduction on women
and children's health. Indirect effects refer to changes in household structure and
parental roles and new or foregone opportunities that are a consequence of
changes in the number and timing of births that may themselves influence health.
While the report focuses primarily on possible direct and indirect effects of
reproductive patterns on women's and children's health, interaction or synergistic
effects may also be operating. In these cases, the presence of two conditions or
behaviors alters their effects. For example, the joint detrimental consequences of
12
OCR for page 13
HYPOTHESES 1 3
using oral contraceptives and smoking are noted in Chapter 4. Numerous other
interaction effects may be occurring, but they are beyond the scope of this report
We then review other possible explanations for relationships between repro-
ductive patterns and health, such as the possibility that other health behaviors
(e.g., use of modern medical care) affect both reproductive patterns and health.
Finally, we discuss the types of evidence on which our findings are based.
DIRECT EFFECTS OF REPRODUCTIVE PATTERNS ON HEALTH
Reproductive Patterns and Women's Health
Practicing physicians and midwives have observed that women who have
many children and women with certain reproductive patterns are at higher risk of
poor health and mortality. These observed relationships may be directly causal or
may be due to confounding factors. In addition, it is possible that the poorer
health of certain women or their children may lead to certain reproductive
patterns, such as reduced fertility. Hypotheses concerning the effects of repro-
ductive patterns on the health of women are summarized in Table 2.1.
There are at least five reasons to believe that women who limit their fertility
will have better health. Fast, each time a woman becomes pregnant, she is at risk
of pregnancy complications and related complications that she does not face
when she is not pregnant. Thus, over the course of a lifetime, women who have
many children are more likely than women who have fewer children to experi-
ence reproductive illness or mortali~merely because they are exposed more
often to the risks associated with each pregnancy. The risks associated with
pregnancy include pregnancy-induced hypertension, ectopic pregnancy, hemor-
rhage, obstructed labor, infection, and, for those not wanting to be pregnant, the
hazards of unsafe abortion. The health benefits of fewer pregnancies are likely to
be greater in regions where prenatal and intrapartum care are poor, because the
risks associated with each pregnancy are greater. These issues are discussed in
greater detail in Chapter 3.
Second, in addition to having fewer pregnancies, women who control their
fertility can avoid pregnancies that may pose higher-than-normal risks to their
health. Research suggests that women who have had many previous pregnancies
may be at higher risk of poor health from a given pregnancy than women who are
pregnant for the second, third, or fourth time. Women who have had many
previous pregnancies may be at higher risk of morbidity and mortality because of
the cumulative toll of previous pregnancies and because of previous reproductive
injury. In particular, they may be more likely to experience complications such as
uterine rupture and hemorrhage than women who have had fewer previous
pregnancies.
The first pregnancy also appears to have a higher risk than the second, third, or
fourth pregnancy. Women who are having their first child appear to be at higher
OCR for page 14
i4 CO~RACE=ION ID REPRODUCTION
TABLE 2.1 Hypothesized Direct Effects of Reproductive Patterns on Women's
Health
Reproductive Pattem
Hypothesized Effect
Number of pregnancies
High-risk pregnancies
First pregnancies
High-order pregnancies
Pregnancy at very young
maternal ages
Pregnancy at older ages
Short interbirth intervals
Unwanted pregnancies ending in
unsafe abortion
Large family size
Pregnancies for women already
in poor health
Use of contraception
Each pregnancy carries a risk of reproductive
morbidity and mortality
Adaptation to pregnancy for the first time
Hemorrhage; uterine rupture; previous reproductive
. .
injury
Inadequate development of reproductive
system and incomplete growth
Adequate prenatal and interpartum care less likely
Body in poorer condition for pregnancy and childbirth
Inadequate time to rebuild nutritional stores and regain
energy level
Abomons performed by unsafe means increase
exposure to injury, infection, hemorrhage, and death
Reduced availability of family resources for women's
health and nutrition
Aggravated health condition
Direct health risks and benefits associated with
ca~tracephve methods
risk of obstructed labor, pregnancy-induced hypertension, and birth complica-
tions. However, since any woman who has children must have a first birth,
women who desire children obviously cannot choose to avoid first pregnancies in
order to lower their risks of morbidity or mortality.
Reproductive morbidity and mortality may also be more common for women
who become pregnant at the very beginning and at the end of their reproductive
years. Pregnancy may be more stressful physiologically to very young women,
OCR for page 15
HYPOTHESES 15
because their reproductive systems are not yet fully mature and they may not yet
have completed their growth. Young girls may also be less likely to detect a
pregnancy early on or, for a variety of reasons, they may deny the pregnancy. In
both cases they may seek prenatal care later in pregnancy than desirable or delay
having an abortion (in situations where either is available). Older women may
encounter problems more frequently during pregnancy and birth because the
ability of their reproductive systems to cope with the burden of pregnancy has
declined with age. Evidence of decline in the function of the reproductive system
with maternal age includes an increased incidence of fetal chromosomal abnor-
malities and spontaneous abortion.
Pregnancies that begin shortly after a previous birth may also pose higher risks
for women. Short interbirth internals, especially if accompanied by intensive
breastfeeding, may prevent a woman from rebuilding depleted nutritional stores
before He next pregnancy begins. This problem is likely to be more serious
among women who are malnourished to begin with and may be exacerbated by a
sequence of closely spaced pregnancies.
A pregnancy that occurs when a woman's health is already jeopardized is
likely to pose a greater risk than a pregnancy for a healthy woman. Women who
are malnourished, who are seriously ill, or who have chronic health conditions are
clearly at higher risk than healthier women. By avoiding pregnancy, women with
health problems may substantially improve their own chances for survival and
good health.
Third, in addition to reducing the total number of pregnancies and avoiding
potentially higher-risk pregnancies, women in many developing countries can
also substantially reduce their risk of reproductive morbidity and mortality by
using contraception to avoid unwanted pregnancies rather than resort to unsafe
abortion to terminate such pregnancies. In many developing countries, abortion
is illegal and is often performed by untrained personnel in unhygienic conditions.
Abortions attempted by women themselves or performed by abortionists under
septic conditions substantially increase a woman's risk of infection, injury or
hemorrhage, and death.
The three hypothesized mechanisms just described suggest that changes in
reproductive patterns may improve health by decreasing exposure to infection,
injury, and other reproductive complications. A fourth possible mechanism is the
use of contraception itself, which may affect women's health. There may also be
a fifth and more general effect of changes in reproductive patterns on women's
health. Most families in developing countries have limited resources that must be
allocated to a variety of family needs. Families with fewer young children to care
for are likely to have more resources (including time, food, and money) to devote
to the health of each family member. For example, women in smaller families
may have more time to go to a clinic for treatment of an illness or for a prenatal
. .
VlSlt.
OCR for page 16
6 CO=RACE=ION AND PRODUCTION
Reproductive Patterns and Children's Health
A woman's reproductive pattern may also have important effects on the health
and survival chances of her children. Children's well-being, especially in the first
year of life, is highly dependent on their mothers' health during and after preg-
nancy. For this reason, some of the hypothesized effects of reproductive patterns
on children's health are closely related to the effects of reproductive patterns on
women's health. Specifically, children who are firstborn or are of high birth
order, children born into larger families, children born to very young or older
mothers, children born after short previous interbirth intervals or before a short
subsequent interbirth interval, and children who were unwanted at the time they
were conceived may be at higher risk of poor health and mortality than other
children. It is also possible that a mother's use of contraception may affect her
child's health directly, for example through effects on lactation. These hypothe-
ses are summarized in Table 2.2.
Birth Order
Since nulliparous women experience more problems during pregnancy, b~rst-
born children may be less healthy at birth, may weigh less at birth (because of
poorer intrauterine growth or shorter gestation), and may experience more trauma
during birth. The parents of firstborn children may also be less experienced in
child care, although this explanation for poorer health among firstborns seems
less plausible in societies in which new parents frequently live with older, more
experienced relatives. Reducing the number of first births that women have is
obviously not a sensible policy objective, since families choosing to have chil-
dren must have a first birth, but delaying first births could be an important policy
objective, particularly for very young women.
Children born of higher-order pregnancies may experience higher risks of
morbidity and mortality for at least two reasons. First, as discussed above,
because of the cumulative toll of numerous previous pregnancies and associated
breastfeeding on maternal nutritional stores (described as the "maternal depletion
syndrome"), mothers of higher-order children may be in poorer health prior to
and during pregnancy, as well as after birth. Women who have reached high
parity (fifth and higher parity) are also more likely to have experienced injures
during childbirth, which may complicate a higher-order pregnancy and birth.
Thus, higher-order children may be at greater risk of poor intrauterine growth,
greater trauma during birth, and, more generally, poorer health than children born
at orders 2, 3, and 4. Second, children born at higher orders may be in poorer
health because their families have fixed resources (such as time, money, food, and
shelter) and more children to care for with these resources. On one hand, the sixth
or seventh child in a poor family may receive less time and attention from parents
than the first or second child did at a comparable age because there are now many
children who need attention. On the other hand, older children may help to care
OCR for page 17
HYPOTHESES 1 7
TABLE 2.2 Hypothesized Direct Effects of Reproductive Patterns on
Children's Health
Reproductive Pattern
Hypothesized Effect
Firstbom children
Higher-order children
Large families
Children born to very young
mothers
Children ham to older mothers
Short interbirth intervals
Unwantedness
Maternal death or illness
(e.g., chronic infection such as ADS)
Contraceptive use
More frequent maternal problems during pregnancy
and childbirth; parents have less experience wad child
care; poorer intrauterine growth
Matemal depletion; cumulative effect of earlier
maternal reproductive injury; poorer intrauterine
growth
limited family resources allocated to more children;
spread of infection among family members
Inadequate development of maternal
reproductive system and incomplete matemal growth;
young mothers less likely to receive adequate
prenatal and intrapartum care or to provide good child
care
Greater risk of birth trauma; greater risk of genetic
abnormalities
Inadequate maternal recovery time (matemal
depletion); competition among similar aged siblings
for limited family resources; early termination of
breastfeeding; low biIthweight; increased exposure to
infection from children of similar ages
(Conscious or unconscious) neglect; child born into a
stressful situation
Early termination of breastfeeding; no maternal care;
disease may be passed to child
Hommonal contraception may interrupt breastfeeding
for younger children in large families and may contribute to the economic well-
being of the family, thus increasing both total family income and possibly per
capita income.
Another hypothesis is that children who have a large number of siblings,
regardless of their own birth order, are more likely to be in poor health. When
there are a large number of children in a household with limited resources, there is
OCR for page 18
~ ~ CO=RACE=ION ED PRODUCTION
increasing competition among children, so each child not just children of higher
birth order—may receive less time, attention, and care. Moreover, a child who
has a larger number of siblings, especially if they live and sleep in crowded
quarters, will be at increased risk of contracting infectious diseases.
Maternal Age
Children born to very young mothers and to older mothers may also be at
higher risk of poor health and mortality. In the case of the children of very young
mothers, as argued above, the reason may be that pregnancy is more stressful
physiologically for adolescents because their reproductive systems are not yet
fully mature, and they may not yet have completed their growth. As a conse-
quence, adolescent girls may be less able to produce healthy babies and may
experience more trauma during childbirth. A second possible reason that the
children of very young mothers may be in poorer health is that these mothers may
be less likely to seek and receive adequate prenatal care and may be less ready
psychologically and materially to care for their children.
Children born to older mothers may also experience greater risks of mortality
and morbidity. As argued above, women at the older end of the reproductive span
may encounter more frequent problems during pregnancy and birth because the
capability of their reproductive systems to cope with the burden of pregnancy has
declined. Children born to older women may have poorer health at the time of
birth because of the greater likelihood of birth trauma or genetic abnormalities.
Birth Spacing
Children born either after or before short interbirth intervals may also be at
higher risk of morbidity and mortality, for several reasons. The first is related
directly to the hypothesized effect of close pregnancy spacing on maternal health.
For women living in poverty who are predisposed to malnutrition or poor health,
a very short interval between one pregnancy and the next may not provide
adequate time for rebuilding nutritional stores and for physiological recuperation.
The consequences for children born after short interbirth intervals may be poorer
intrauterine growth as well as a higher risk of preterm birth.
We noted above that competition among siblings in large families for scarce
resources may mean that higher-order children, or possibly all children, may be at
greater risk of poor health. Competition among children for family resources
may be even more of a problem among children of similar ages, especially when
they are young, because they have similar needs. When two births are spaced
very closely, each child may not receive as much care and attention as he would if
he did not have a sibling of roughly the same age. Close birth spacing can also
create even more direct competition among siblings in the case of breastfeeding.
OCR for page 19
HYPOTHESES 19
A mother who becomes pregnant soon after a child is born is likely to wean that
child sooner than she would had she not become pregnant again. Since breastfeed-
ing is an important determinant of child health in many societies, premature
termination of breastfeeding often substantially increases a child's exposure to
infection and increases the risk of malnutrition.
Close birth spacing may also increase children's exposure to infectious dis-
eases by fostering transmission of infections among household members who are
of similar ages. Many infectious childhood diseases affect a relatively narrow age
range. If there is more than one child in the household in that age range, the
chances of introducing the disease to the household and transmission of higher or
repeated doses of the infectious organism may be dramatically increased, thus
increasing the likelihood of multiple or more severe illnesses. This is especially a
problem with diarrhea! diseases, for which repeated incidence may result in
malnutrition, and with measles, for which transmission in the household may be
associated with more severe and fatal infection.
Unwanted Births
Finally, children who were unwanted at the time they were conceived may be
at greater risk of poor health and mortality than other children. In households
with limited resources, parents may, consciously or unconsciously, discriminate
against unwanted children in the allocation of food parental time and attention, or
preventive and therapeutic health care. An alternative hypothesis is that children
who are unwanted often are conceived when the family or the mother is under
economic, social, or psychological stress, and the child is at greater risk simply by
being born into a stressful situation.
Maternal Illness arid Death and Effects on Child Health
Reproductive patterns may have another type of effect on the-well-being of
families and especially children, through their association with maternal morbid-
ity and mortality. The death of a mother, whether due to reproductive or other
causes, is likely to cause major disruption in the lives of her children, as well as a
breakup of the household in which she and her children lived. In addition to the
serious emotional consequences for children, the disruption following their
mother's death may be extremely detrimental to their physical health, particularly
if they are very young and breastEeeding has ended. Serious illness or reproduc-
tive injury may also prevent a woman from caring adequately for her children,
with consequent negative effects on their health and survival chances. Maternal
incapacity and death may be a growing burden on societies in which AIDS affects
substantial numbers of women of reproductive age. Furthermore, it is possible
that certain infectious diseases can be passed from mother to child.
OCR for page 20
20 CONTRACEPTION kD REPRODUCTION
INDIRECT EFFECTS OF REPRODUCTIVE PATTERNS ON HEALTH
Changes in reproductive patterns through control of fertility are also hypothe-
sized to have important indirect effects on the health of women and children.
Although some means of controlling fertility (including withdrawal and absti-
nence) are theoretically always available to couples, the availability of modern
methods of contraception brings the process of fertility regulation more firmly
into the control of couples and of women themselves. Successful intervention in
what was formerly seen as a natural process may change couples' or families'
attitudes about their ability to make changes in other traditional practices. These
practices may include those related to child care, prenatal diet and care for
women, and the use of modern health services. The ability to regulate fertility
may also increase women's autonomy and give them greater authority to make
decisions concerning their own health and the health of their children.
In some settings, increased control over fertility and the increased predictabil-
ity of pregnancy timing that comes from contraceptive use may also make it
easier for women to finish their education, to participate in the labor force, or to
hold better-paying jobs. Higher educational attainment, work outside the home,
or a better job are all likely to increase family income, which can then be spent on
a more nutritious diet, better clothing and shelter, improvements in sanitation and
water supply, and health services for all family members. In some societies, the
fact that women make financial contributions to the household budget may also
give them additional decision-making power in allocating household resources to
themselves and their children, thus potentially improving their health.
Women who have fewer children or fewer young children to care for may be
under substantially less physical and psychological stress than women with very
large families, especially women in poor families, in which the resources to care
for children are often scarce or inadequate. Furthermore, the ability to control
fertility may also change a woman's outlook on life and may contribute to her
psychological well-being (Dixon-Mueller, 1989~.
In other settings, the ability to control fertility may create new tensions in the
family, at least in the short run. The process of making explicit decisions about
reproductive matters may lead to disagreement between spouses, conflicts be-
tween parents and their adult children about family size, and anxiety about
violating traditional, often religious ideals surrounding sexual practices and child-
bearing.
Another hypothesized indirect effect of family planning on health relates to the
use of health services. In countries where the program is strong and well-organ-
ized, family planning services may serve as an introduction for women to mater-
nal and child health care services. Contact with family planning clinics may
provide these women with information about how the health care system worked,
referrals to other types of care, and often the confidence to deal with other types
of health care workers. In other areas the opposite case may occur, with women
being introduced to family planning through contact with the health care services.
OCR for page 21
HYPOTHESES 2 ~
OTHER POSSIBLE EXPLANATIONS
Reproductive patterns and women's and children's health may be associated
with one another, without the former causing the latter, either directly or indi-
rectly. A third factor may cause both. For example, a baby born after a
pregnancy of short gestation is more likely to be in poor health and to be born
within a short interval after the preceding birth. Although the short interval is not
the cause of the child's poor health, both the short interval and the child's poorer
health are due to the short gestation of the pregnancy. Or it is possible that the
direction of causation runs from health to the reproductive pattern. For example,
if a child dies shortly after birth, breastfeeding will be shorter than it otherwise
would have been. As a consequence, postpartum amenorrhea (the infertile period
following a birth, which is related to the duration and intensity of breastfeeding)
will be shorter. Unless the couple compensates by practicing contraception
longer than it would have had the child not died, the result will be a shorter birth
interval. In this case, the birth interval is short because the child died.
All couples make implicit or explicit choices about whether or not to control
their fertility, and, if they do decide to intervene, about how many children to
have and when to have them. Decisions related to fertility control, family size,
and birth spacing are unlikely to be entirely independent of women's and chil-
dren's health or of other decisions people make which have consequences for
their health. For example, a couple that experiences achild's death may choose to
have another child to "replace" the one who died. Or when child mortality rates
are high, couples may wish to "hedge" against the possibility of a child death by
having additional births to increase the chances that a certain number of children
will survive until maturity. Either of these mechanisms could result in a positive
relationship between a large family and high child mortality, but, in these cases,
fertility is high because mortality is high. A similar relationship could arise if
some couples choose to have fewer children so that they can "invest,' more in the
health and education and material well-being of each child. In this case again, the
relationship runs from (desired) health to fertility.
Another hypothesis about the observed association between fertility patterns
and the health of women and children is that couples who use contraception to
limit family size, space their children, and avoid unwanted pregnancies may
simply be different from other couples in ways that affect both health and
childbearing. An example of a couple's choices that affect both fertility and
health involves the use of health services. As we noted above, in settings in
which family planning programs are very strong, contact with family planning
services may introduce families to other health services that they were previously
unaware of. It is also possible that families who have previous experience with
health services and are accustomed to using them are more likely to be aware of
available family planning services and are also more likely to feel comfortable
using them. Thus, it may be a familiarity with He health system that causes
increased contraceptive use rather than vice versa
OCR for page 22
22 CONTRACEPTION ED PRODUCTION
Parents who take action to prevent illness and who seek medical care when
illness occurs may also be more willing to attempt to control their fertility, to try
using contraception, and to have the persistence to seek out contraceptive services
when they are not readily available. Undertaking both health-related behavior
and control of fertility may require a nonfatalistic view of life, in which it is
possible and socially acceptable to try to intervene in natural processes such as
illness and conception. For many couples in developing countries, obtaining
effective health care and fertility control methods may require substantial persis-
tence and knowledge of how to obtain information and deal with an ineffective
delivery system. Adults who have these skills, abilities, and beliefs are likely to
use health services, to carry out health-improving practices at home, and to use
contraceptive services.
Finally, families with more financial resources and education are likely to be
in better health—because they live in a better physical environment, because their
diet is better, and because they receive better health care. These same families
may also have fewer children because they prefer smaller families or because
they have better access to contraceptive facilities.
In short, the observed association between reproductive patterns and women's
and children's health may result from the fact that families who take measures to
protect their members' health are also more likely to control their fertility, as well
as from causal effects of reproductive patterns on health. This possibility is
important to consider if we want to determine the likely effects of changes in
reproductive patterns on health, and we return to it in subsequent chapters.
AVAILABLE EVIDENCE
Probably the most direct and convincing way to distinguish among the hy-
potheses discussed above would be to conduct controlled randomized double-
blind experiments. For example, some women would be randomly assigned to
have their fast child at age 16 and others would wait till age 20. Or two otherwise
identical sets of communities could be chosen for study and contraception would
be provided in one group and not the other. Such experiments, however, are
difficult to perform, and they would raise ethical problems even if they were
feasible. Consequently, it is not surprising that the extant evidence is based not
on experimental studies, but rather on observational data collected through sur-
veys or longitudinal data from nonexperimental settings.
For policy purposes, we would like to be able to distinguish among the
alternative hypotheses discussed above. To illustrate, take the example of the
relationship between young maternal age and child health. If the reason that the
children of teenagers are less healthy than the children of older women is that
teenagers are less likely to seek prenatal care, further research could seek to
understand the reasons and to try to remedy the situation. If the relationship
between young maternal age and child health is physiological, due to incomplete
OCR for page 23
HYPOTHESES 23
maternal growth, a policy that helps women postpone childbearing until later ages
should result in improved child health. If, alternatively, teenage mothers have
poorer child health outcomes because girls who become pregnant as teenagers are
poorer mothers regardless of the ages at which they bear their children, then
postponing childbearing for these women will not necessarily have beneficial
effects for the children's health. A key question is whether teenagers outgrow-
physiologically, psychologically, or economicall~whatever causes their chil-
dren to have poorer health outcomes, or whether it is a persistent characteristic of
the types of women who become pregnant as teenagers.
The evidence regarding the hypothesized effect of maternal age on children's
health typically comes from analyses of data on maternal ages at children's births
and the children's health (typically survival measures) that show health outcomes
to be poorer for children born to young mothers under age 20 than to older
mothers ages 2~29. Earlier studies tended to consider the simple correlation
between maternal age and child health. Such a correlation, however, says nothing
about which among the possible mechanisms discussed in this chapter might
account for this association. For example, births to teenage mothers are more
likely than births to older mothers to be first-order births, which have a greater
risk of low birthweight and other problems, as discussed above. Hence, to assess
the effect of being born to a teenage mother, it is important to hold constant the
effect of parity and, in essence, consider age differentials within parity categories.
As another example, teenage mothers may have less education or lower incomes
than older mothers. In such a case, it is desirable to control for education and
income, so as not to attribute to age what is really a result of low education or
income. More recent studies have used multivanate statistical methods in an
attempt to deal with these issues.
The remaining possibilities are more difficult to distinguish, especially in
large-scale population surveys, which have provided much of the evidence on the
relationships between reproductive patterns and child health. To assess the
possibility of a physiological mechanism, one would ideally like to consider
gynecological age (years since menarche) and assess its relation to pelvic size and
the women's nutritional status, and how these, in turn, affect her baby's health.
Psychological maturity is even more difficult to assess; for example, teenagers
tend to be more egocentric than older women and less likely to respond to the
needs of others. One could look at the health-related behaviors that psychological
development could be expected to affect, to see, for example, if pregnant teen-
agers are less likely to use prenatal care (appropriately). However, assessing the
effects of health care on health outcomes is complicated by the fact that unobser-
ved factors that affect decisions to seek health care may also affect health
outcomes. For example, as noted above, women with a greater concern about
health may be both more likely to seek health care and more likely to engage in
other behaviors that promote good health. In such a case, a simple correlation
between health care and health would overstate the direct effect of the former on
OCR for page 24
24 CONTRACEPTION ID REPRODUCTION
the latter. In other cases, women in poor health may be more likely to seek health
care because of specific needs.
The last example illustrates a problem generic to all research that uses nonex-
perimental observational data: no matter how many known correlates and poten-
tial confounding variables are controlled (e.g., parity, education, and income in
assessing the effect of young maternal age on child health), it is always possible
that there may be unobserved factors that may be correlated with both the
reproductive patterns of interest and the health outcome being considered that
contribute to their relationship; hence, even when other observed factors are
controlled, it is possible that the estimated relationship is not entirely causal.
Some analysts have used structural models to deal with these issues, but to date
such methods have been used infrequently to study the effects of reproductive
patterns on women's and children's health, particularly in developing countries.
An example of using structural models is the simultaneous equation frame-
work as commonly used in economics, for example, when fertility is modified in
response to the expectation and occurrence of child mortality, while child mortal-
ity may be affected by reproductive patterns. To disentangle the two effects,
which operate in opposite directions, and to statistically distinguish only the latter
effect, which is one focus of this report, the scientist requires information on an
independent variable that directly affects fertility and does not directly affect
child mortality. This variable could provide the information needed to identify
statistically and thus estimate the one-way effect of independent changes in
reproductive patterns on child (or maternal) mortality. The problem is to find
such an identifying variable that can be plausibly excluded from entering the
mortality determining process. This is difficult when studying complex, jointly
determined household demographic processes such as fertility and child mortal-
ity, especially when the assumptions made in choosing identifying variables are
often unverifiable.
The evidence reviewed in this report comes from many different sources:
large-scale population-based surveys that ask women about their pregnancies and
children's mortality, smaller-scale longitudinal studies and hospital or clinic
samples that often include physiological information, and data on births and
deaths in historical populations. The characteristics and advantages and disad-
vantages of these various types of studies are reviewed in the chapters ahead.
However, it is important to note that none of the studies to date has simultane-
ously addressed all the different types of issues just discussed.
This report focuses principally on the evidence from previous research con-
cerning the hypotheses about the direct effects of family planning or reproductive
control on the health of women and children. Although it is possible that indirect
effects may be equally or more important than the direct effects under considera-
tion, investigation of these hypotheses is outside the scope of this report. We
return to the subject of the indirect effects in Chapter 7.
Representative terms from entire chapter:
poor health
