When children have children: Can postponing early motherhood help children survive longer?

In 2010, approximately 34% of young women in developing countries – some 67 million – married before reaching 18 years of age. An additional 14-15 million women will marry as children or adolescents every year in the coming decades. Child marriages lead to pregnancies and childbirths at an early age, which can have negative consequences for the health of both mother and child. Does the age at which motherhood takes place matter, and can postponing motherhood into adulthood help increase the chances of children surviving beyond five years of age? My study of teen pregnancies amongst Bangladeshi girls shows that age does matter, and it matters quite a lot.

Globally, in developing countries excluding China, one in three girls will probably be married before they are 18, according to UNFPA figures from 2012. Bangladesh has the highest rate of child marriages in Asia (and the third-highest rate worldwide); two in three women marry as children or adolescents in this country. This exceptionally high rate of child marriages in Bangladesh persists despite a minimum legal marriage age of 18 years for women, and it leads to more teenage pregnancies and a care burden for young women. A survey interviewing 72,662 Bangladeshi mothers in 2001 showed that 10% of interviewed women had their first child between the ages of 10 and 14 years, and another 69% of them had their first child between the ages of 15 and 19 (Figure 1).

Figure 1: Age at which Bangladeshi women have their first child

In general, we know that adolescent childbearing is associated with negative health outcomes for both mother and child. The mother faces an increased risk of premature labour, labour-related complications, and death during delivery (Senderowitz, 1995). She  may also suffer an injury, an infection or a serious health limitation, such as an obstetric fistula or perineal laceration (UNICEF, 2001), due to giving birth. These problems are caused both by physical immaturity and poor socio-economic conditions of young mothers, including a lack of access to sufficient antenatal and obstetric care (WHO, 1999).

The child of an adolescent mother is at a higher risk of a low birth weight (Restrepo-Méndez et al., 2015), which is mainly associated with poor maternal nutrition of adolescents during pregnancy (UNICEF, 2001). Low birth weight is, in turn, a frequent cause of death in the first year of life of infants (McCormick, 1985, Sohely et al., 2001). Apart from biomedical reasons, there are additional channels that link adolescent pregnancies to higher mortality in early childhood. These include insufficient access to maternal health care services and lack of experience in taking care of children.

A better understanding of the link between adolescent childbearing and young children’s survival chances is important as scientific evidence can drive policy changes, particularly in enforcing the minimum legal marriage age in Bangladesh. It can also inform the advocacy of changes in cultural practices. Thus, the central question is: Can postponing motherhood of teenage girls help their children to survive beyond infancy or childhood?

Building on previous knowledge, I looked more closely at the impact of adolescent childbearing on the mortality of young children at different ages between 0 and 5 years. The goal was to separate the effect of having a child at an early age from the fact that poorer (and, frequently, less healthy) mothers tend to marry younger and might therefore have less healthy children. The idea is the following: if children born to young mothers suffer higher mortality in early childhood due to biological factors, such as physical immaturity of mothers and the resulting low birth weight of their children, then we should observe different mortality rates not only between children born to adolescent and adult mothers, but also among siblings born to the same mother in her adolescence and adulthood—that is, in different phases of her life.

It turns out that children born to young mothers (child brides in Bangladesh) are more likely to die in the first year of life than their siblings born later on. This is true irrespective of how rich the household is (left graph in Figure 2). Only in poor households, these negative effects extend up to the child’s fifth birthday (black and blue lines in right graph of Figure 2).

In the two graphs below, we see how much lower the probability of death for an infant or a child is if the mother is older than 10-14 years. The age of the mother is displayed in five-year age groups on the horizontal axes. Different lines indicate different income groups (poorest Quintile 1 – black; Quintile 2 – blue; Quintile 3 – green, Quintile 4 – red; richest Quintile 5 – yellow). The percentage of increased risk of early childhood mortality per age group is shown on the vertical axes of the graphs. The left graph depicts infant mortality (up to one year of age) while the right graph shows child mortality (between one and five years of age).

The graphs show that up to one year of age, the income of the family does not really matter (left) while between one and five years of age, a higher income can help outweigh the negative effect of teenage pregnancies (right). The downward trend observable in the left graph is universal for all income groups and it indicates that all children have higher survival chances in the first year of life if their mother is not a teenager. In the right graph, a similar downward trend is observable only for the two poorest income groups, which means that only in poorer families, children of ages one to five have worse survival chances if their mother is a teenager. The three richer income groups show no downward trend (and their slightly upward trend is statistically not important) which means that in richer families, the mother’s age does not really influence her child’s survival if the child managed to survive the first year of life. The graphs are based on my study of adolescent childbearing among Bangladeshi women.

Figure 2: Infant and child mortality effects of maternal age for five different wealth quintiles

These results confirm my idea that the effects of adolescent pregnancies on child survival in the first year of life are of biological nature because they are universal. Possibly, they are related to the immaturity of young girls’ bodies and to low birth weight of their children. Beyond infancy, these negative effects remain only in poorer households, which is consistent with the notion that richer households are able to counteract a biologically induced, worse starting position of children born to adolescent mothers by compensatory investments in child health. However, these investments do not become effective until the children reach the age of one year old.

Finally, the estimated effects are substantial in magnitude: for instance, the survival chances of children born to mothers aged 20-24 years are 56% higher in infants’ first year of life and 24% higher when the child is aged between one and five, when compared to their older siblings who were born to young mothers (aged 10-14 years). These effects either persist or become even larger when comparing adolescent maternal age (10-14) to older ages (25-29, 30-34, etc. up to 45-49 years). Importantly, these results remain true also when I exclude older women or first-born children from the sample.

To summarize, I have shown that infants and children have a much better chance of survival when their mothers are adults. The postponement of motherhood into adulthood could help prevent around 12,900 infant and 18,700 under-five deaths annually in Bangladesh, as rough calculations explained in my paper show. These effects can be directly attributed to the practice of child marriages.

This article is based on a recent paper I authored, see here.

Main reference:

S.K. Trommlerová (2020). When Children Have Children: The Effects of Child Marriages and Teenage Pregnancies on Early Childhood Mortality in Bangladesh. Economics & Human Biology 39, 100904.

Other references:

McCormick, M. (1985). The contribution of low birth weight to infant mortality and childhood morbidity. The New England Journal of Medicine 312(2), 82-90.

Restrepo-Méndez, M.C., D.A. Lawlor, B.L. Horta, A. Matijasevich, I.S. Santos, A.M. Menezes, F.C. Barros and C.G. Victora (2015). The association of maternal age with birthweight and gestational age. Paediatric and Perinatal Epidemiology 29, 31-40.

Senderowitz, J. (1995). Adolescent Health: Reassessing the Passage to Adulthood. World Bank Discussion Paper 272. World Bank, Washington DC.

Sohely, Y., D. Osrin, E. Paul and A. Costello (2001). Neonatal mortality of low-birth-weight infants in Bangladesh. Bulletin of the World Health Organization 79(7), 608-614.

UNFPA (2012). Marrying Too Young. End Child Marriage. United Nations Population Fund, New York.

UNICEF (2001). Early Marriage – Child Spouses. Innocenti Digest 7. Innocenti Research Centre, Florence.

WHO (1999). The Risks to Women of Pregnancy and Childbearing in Adolescence. WHO, Division of Family Health, Geneva.