Childhood nutrition and later fertility: pathways through education and pre-pregnant nutritional status

Is height related to fertility? An evaluation of women from low- and middle-income countries

OBJECTIVES

To present an empirical description of the association between height and lifetime fertility in women from low- and middle-income countries, allowing for flexible functional relationships.

METHODS

A pooled sample (N = 846 257) of women ages 35-49 in Demographic and Health Surveys (DHS) from 64 countries, with regional samples for Latin America, South Asia, and sub-Saharan Africa. Flexibly-estimated structured additive regression models estimate variations in the height-fertility relationship over the height distribution.

RESULTS

Across samples, height is shown to have nonlinear relationships with number of children ever born and age at first birth. Number of children increases with height until a maximum below average height, after which the number of children decreases. Age at first marriage decreases with height until a minimum below average height, and then increases. Except at the shortest heights, much of the variation in fertility is suggested to reflect socioeconomic differences across heights. At the shortest heights, variation is suggested to reflect later ages at first birth, except for women in sub-Saharan Africa.

CONCLUSION

A nonlinear relationship is indicated between height and fertility. Much of the relationship is suggested to reflect height-variations in socioeconomic status and age at first birth.

Impact of Nutrition on the Next Generation: The INCAP Longitudinal Study

BACKGROUND

The design of the original nutrition supplementation trial that was conducted from 1969 to 1977 in 4 villages in rural Guatemala to evaluate the benefits of improving nutrition during pregnancy and early childhood, combined with several follow-up studies, provides unique data to examine the effects of improving nutrition on the next generation.

OBJECTIVE

This article provides a summary of the key findings from the INCAP Longitudinal Study on the intergenerational effects of improving nutrition on the growth and well-being of the next generation.

METHODS

The key outcomes include offspring birth size as well as attained size and body composition through age 11 years. The sample sizes varied from approximately 200 to 800 depending on the timing of the follow-up studies and data collection protocols. The effects of parental birth size, maternal linear growth from birth through adulthood, and exposure to the nutrition intervention, that is, Atole versus Fresco during critical periods from prenatal through age 15 years, have been examined using complex models and approaches.

RESULTS

Overall, these publications demonstrate clear improvements in the growth of the next generation. Effects were seen primarily for maternal exposure to Atole and were larger for boys compared to girls. Stunting during early childhood among girls was also a significant predictor of offspring birth size, and younger age at first pregnancy (<20 years) was associated with an increased risk of stunting in the offspring.

CONCLUSIONS

These studies have contributed significantly to our understanding of the importance of investing in nutrition, especially during early childhood for future generations.

Computing the Z Score and Centiles for Cross-sectional Analysis: A Practical Approach

Although Z scores have been reported in the literature, one of the problems for the nonstatistician is understanding the systematic approach used to compute the predicted mean and standard deviation, components of the Z score equation, which may vary as the independent variable changes over time (eg, gestational age). This review focuses on a step-by-step analysis using linear, quadratic, and fractional polynomials to compute the mean and standard deviation as a function of a continuous independent variable. Once the mean and standard deviation are computed, the Z score and centile can be derived and Z score calculators created that enable investigators to implement the results in the laboratory and/or clinical setting.

Developmental influences on fertility decisions by women: an evolutionary perspective

Developmental environments are crucial for shaping our life course. Elements of the early social and biological environments have been consistently associated with reproduction in humans. To date, a strong focus has been on the relationship between early stress, earlier menarche and first child birth in women. These associations, found predominately in high-income countries, have been usefully interpreted within life-history theory frameworks. Fertility, on the other hand--a missing link between an individual's early environment, reproductive strategy and fitness--has received little attention. Here, we synthesize this literature by examining the associations between early adversity, age at menarche and fertility and fecundity in women. We examine the evidence that potential mechanisms such as birth weight, childhood body composition, risky health behaviours and developmental influences on attractiveness link the early environment and fecundity and fertility. The evidence that menarche is associated with fertility and fecundity is good. Currently, owing to the small number of correlational studies and mixed methodologies, the evidence that early adversity predicts fecundity and fertility is not conclusive. This area of research is in its infancy; studies examining early adversity and adult fertility decisions that can also examine likely biological, social and psychological pathways present opportunities for future fertility research.

Female Literacy Rate is a Better Predictor of Birth Rate and Infant Mortality Rate in India

BACKGROUND

Educated women are known to take informed reproductive and healthcare decisions. These result in population stabilization and better infant care reflected by lower birth rates and infant mortality rates (IMRs), respectively.

MATERIALS AND METHODS

Our objective was to study the relationship of male and female literacy rates with crude birth rates (CBRs) and IMRs of the states and union territories (UTs) of India. The data were analyzed using linear regression. CBR and IMR were taken as the dependent variables; while the overall literacy rates, male, and female literacy rates were the independent variables.

RESULTS

CBRs were inversely related to literacy rates (slope parameter = -0.402, P < 0.001). On multiple linear regression with male and female literacy rates, a significant inverse relationship emerged between female literacy rate and CBR (slope = -0.363, P < 0.001), while male literacy rate was not significantly related to CBR (P = 0.674). IMR of the states were also inversely related to their literacy rates (slope = -1.254, P < 0.001). Multiple linear regression revealed a significant inverse relationship between IMR and female literacy (slope = -0.816, P = 0.031), whereas male literacy rate was not significantly related (P = 0.630).

CONCLUSION

Female literacy is relatively highly important for both population stabilization and better infant health.

Nutritional influences over the life course on lean body mass of individuals in developing countries

The double burden of childhood undernutrition and adult-onset adiposity in transitioning societies poses a significant public health challenge. The development of suboptimal lean body mass (LBM) could partly explain the link between these two forms of malnutrition. This review examines the evidence on both the role of nutrition in “developmental programming” of LBM and the nutritional influences that affect LBM throughout the life course. Studies from developing countries assessing the relationship of early nutrition with later LBM provide important insights. Overall, the evidence is consistent in suggesting a positive association of early nutritional status (indicated by birth weight and growth during first 2 years) with LBM in later life. Evidence on the impact of maternal nutritional supplementation during pregnancy on later LBM is inconsistent. In addition, the role of nutrients (protein, zinc, calcium, vitamin D) that can affect LBM throughout the life course is described. Promoting optimal intakes of these important nutrients throughout the life course is important for reducing childhood undernutrition as well as for improving the LBM of adults.