Child spacing

國

立 政 治 大 學

‧

N a tio na

l C h engchi U ni ve rs it y

2 Literature Review

The study of human fertility has followed, from multidisciplinary standpoints, the main dynamics of population transitions in the world. Those transitions, whether attained as responses to economic transformations at regional, country and household levels, or to technological innovations regarding family planning mechanisms, among other possible causes, have fueled scholarly discussion for decades. The truth is that in the past six decades, family size has fallen by half –from 5 to 2.5 children per family– in a worldwide trend (Darroch, 2013); and family planning, boosted as public policy for developed and developing countries alike, is more widely used and has improved parental decision regarding number and timing of fertility (Powell, 1995).

These factors introduce a new variable in the household fertility decision-making, child spacing. The consistent decline of family size expands the possibilities for families, that deal with the same fertility time constraint but want fewer children. Therefore, time spacing between births becomes a key issue, especially when these decisions have important consequences in the life outcomes of the members of the household.

2.1. Child spacing

Decisions regarding child spacing are also determined by heterogeneous characteristics that surround human behavior. In their comprehensive cross-country comparative study, Rodriguez, et al. (1984) found that birth intervals were determined by early behavior and socioeconomic differences that affect the reproductive process, especially for transitional societies, i.e. developed countries, such as education, through its incidence breastfeeding and contraceptive behavior; and age at the start of the interval, through aging sterility, ultimately ceasing the opportunity window for reproduction.

In regards to age, for the interval between the first and second child, older women were found to be more likely to space their births closer than younger women did (Wineberg & McCarthy, 1989). These reflect the pressure due to the fertility time constraint and the uses of contraception among younger women experienced in the last decades since Morgan and Rindfuss (1999) found that the relationship between early childbearing, parents having more children in their lifetimes and the subsequent rapid pacing of the births, weakened deeply in comparison to previous studies (Bumpass, Rindfuss & Janosik, 1978; Trussell & Menken, 1978).

Among other determinants for the spacing between children are the preferences regarding parental presence, specifically those in terms of breastfeeding. The prolonged

‧

立 政 治 大 學

‧

N a tio na

l C h engchi U ni ve rs it y

breastfeeding does not only benefit child nurture and development but is also the cause of lactational amenorrhea in breastfeeding moms (Smith, 1985). Additionally, breastfeeding practices are also subject to cultural traditions and societal influence, and as Smith (1985) also finds, the median of some countries in Southeast Asia and Sub-Saharan Africa between 15 to 30 months of prolonged breastfeeding. Thus, whether as byproduct decision of increased education or indirectly through cultural legacy traditions, longer periods of full-breastfeeding increase the spacing between births.

Returning to Rodriguez, et al. (1984), households in developed countries that have tools to highly control their fertility, evaluate the timing and spacing of early births; but the later ones may include pregnancies product of contraceptive failures. For which, the authors suggest accounting for socioeconomic variables such as housing tenure, race and religion. Nonetheless, there are also unaccounted for occurrences in the household that might lead to changes in child spacing. For instance, Winikoff (1987) suggests that unusual long intervals between births can be caused by disruptions to the family ecosystem, e.g. divorce, death of one of the parents. Or on the other hand, biological factors mainly associated with the mothers, such as predisposition to fetal loss, death of the previous child, abortions, and the mother’s health on itself, are all associated with the variations in the length of birth intervals (Winikoff, 1987).

Considering the aforementioned determinants, families decide upon optimal length intervals but this decision has consequences in life outcome for the offspring and the household on itself. It’s also argued that households may foresee these unwanted outcomes and modify their selection of spacing length. On the macro level, longer interval reduces the potential of child production when considering the fertility time constraint, thus reducing the rate of population growth. Alternatively, it can also impact the rate of growth of a population through its incidence on the average spacing between generations (Newman, 1983).

At the household level, larger spacing between children serves to reduce the family size (Hanushek, 1992), which is, in turn, a key factor in increasing the family resources allocated, such as investments in human capital and parental time, namely resource-dilution hypothesis of Blake (1981). Still, on the micro-level, longer child spacing increases the cost of raising children, when assuming economies of scale, i.e.

children of close ages have similar needs that can be met more efficiently when attending their needs collectively (Newman, 1981, as cited in Newman & McCulloch, 1984). On

‧

立 政 治 大 學

‧

N a tio na

l C h engchi U ni ve rs it y

the contrary, according to Powell (1995), longer birth intervals can favor the recovery from financial difficulties, consumption smoothing and proper spending planning.

Furthermore, the spacing decision has not only consequences on how the income is allocated, but for starters, how is it made. For instance, in dynamic models of fertility, delaying the timing of first birth and closed spacing decisions reduce the effects of childbearing in the labor market, i.e. reducing the opportunity cost of having children, represented in household forgone wages, human capital investments and depreciation (Troske, 2013).

When the focus is changed to spacing outcome effects in children – while building on the resource-dilution hypothesis–, longer spacing determines the number of children clustered at a particular age group which prominently determines the allocation of household resources (Powell, 1995). In this regard, the more intensive investment in children can be coined to higher quality, specifically reflected educational performance variables of children with longer spacing intervals.

Nonetheless, the more immediate results of birth spacing are those related to the health adverse perinatal and infant outcomes. Research suggests that when births are spaced closely or too far apart, there’s an increase in the risk of adverse perinatal outcomes such as preterm birth, low weight at birth, smaller size for gestational age and underweight (Conde-Agudelo, Rosas-Bermúdez, & Kafury-Goeta, 2006; Conde-Agudelo, et al., 2012).

For surviving offspring, regardless of these adverse predispositions, they are more likely to suffer from short- and long-term health consequences of the short birth spacing. Notably, most effects are associated with nutrition and weight. For instance, Rutstein and Johnson (2004) compared 24-29 months intervals to 36-41 months ones, finding a decrease in underweight of 29% for the long-spaced births. A year later, Rutstein (2005) elaborated on another outcome variable, nutrition, and found that shorter birth spacing has a clear pattern of more undernutrition. In this sense, his empirical research found that the association of chronic malnutrition with birth intervals was statistically significant in 6 out of 14 surveys that collected anthropometric measurements data, while the relationship of spacing with general malnutrition was found significant in 5 surveys.

Incidences in the quality of nutrition are of particular interest when they become persistent and its cumulative effects transform into long-term impacts on a child’s health, i.e. stunting, low height-for-age parameter. When the relationship between longer spacing

‧

立 政 治 大 學

‧

N a tio na

l C h engchi U ni ve rs it y

36 months reduced stunting from 10% to 50% (Dewey & Cohen, 2007). This is a particularly pressing issue for the developing world, where leading risk factors are primarily related to communicable, maternal, perinatal, and nutritional conditions; in stark contrast with developed countries, where the risk is mainly associated with non-communicable diseases (Lopez, et al., 2006).

All of the above puts into perspective the deleterious effects on children either at one point in time or in the long-run of those who survive. But it is more important to consider that the persistence and worsening of these health –and other household’s–

impacts as a result of the length of the spacing on children might deeply reduce the odds of survival for children past certain ages. The triggering of all possible positive consequences of the length of birth intervals and reduction of family size, described above relies on the assumption of living offspring. In the end, reduction of child mortality is a developmental, human and ethical priority for the world’s agenda, especially in the developing world, where the incidence of this phenomenon is still far from fully mitigated.