Multidimensional life table estimation of the total fertility rate and its components.

Using discrete-time survival models of parity progression and illustrative data from the Philippines, this article develops a multivariate multidimensional life table of nuptiality and fertility, the dimensions of which are age, parity, and duration in parity. The measures calculated from this life table include total fertility rate (TFR), [corrected] total marital fertility rate (TMFR), parity progression ratios (PPR), age-specific fertility rates, mean and median ages at first marriage, mean and median closed birth intervals, and mean and median ages at childbearing by child's birth order and for all birth orders combined. These measures are referred to collectively as "TFR and its components." Because the multidimensional life table is multivariate, all measures derived from it are also multivariate in the sense that they can be tabulated by categories or selected values of one socioeconomic variable while controlling for other socioeconomic variables. The methodology is applied to birth history data, in the form of actual birth histories from a fertility survey or reconstructed birth histories derived from a census or household survey. The methodology yields period estimates as well as cohort estimates of the aforementioned measures.

Multivariate analysis of parity progression-based measures of the total fertility rate and its components.

This article describes a methodology for applying a discrete-time survival model-the complementary log-log model-to estimate effects of socioeconomic variables on (1) the total fertility rate and its components and (2) trends in the total fertility rate and its components. For the methodology to be applicable, the total fertility rate (TFR) must be calculated from parity progression ratios (PPRs). The components of the TFR are PPRs, the total marital fertility rate (TMFR), and the TFR itself as measures of the quantum of fertility, and mean and median ages at first marriage and mean and median closed birth intervals by birth order as measures of the tempo or timing of fertility. The focus is on effects of predictor variables on these measures rather than on coefficients, which are often difficult to interpret in the complex models that are considered. The methodology is applicable to both period and cohort data. It is illustrated by application to data from the 1993, 1998, and 2003 Demographic and Health Surveys (DHS) in the Philippines.

Effects of population policy and economic reform on the trend in fertility in Guangdong province, China, 1975-2005.

An analysis of data mainly from China's 1990 and 2000 censuses and 2005 mini-census shows how fertility decline between 1975 and 2005 in the province of Guangdong has been influenced by both fertility policy and economic and social development. Guangdong's development since 1975 has been very rapid and has attracted huge numbers of migrants from other provinces. The analysis of the province's fertility trend from 1975 shows clearly the influence of fertility policy on the trend. The analysis also shows that economic development has brought about large changes in population composition by urban/rural residence, education, occupation, and migration status, which, together with large fertility differentials by these characteristics, have contributed substantially to Guangdong's fertility decline, in large part through changes in proportions currently married.

Does biofuel smoke contribute to anaemia and stunting in early childhood?

BACKGROUND: Reliance on biomass fuels for cooking and heating exposes many women and young children in developing countries to high levels of air pollution indoors. Exposure to biomass smoke has been linked to reduced birth weight, acute respiratory infections, and childhood mortality. This study examines the association between household use of biofuels (wood, dung, and crop residues) for cooking and heating and prevalence of anaemia and stunting in children. METHODS: Data are from a 1998-99 national family health survey in India, which measured height, weight, and blood haemoglobin of 29 768 children aged 0-35 months in 92 486 households. Multinomial logistic regression is used to estimate the effects of biofuel use on prevalence of anaemia and stunting, controlling for exposure to tobacco smoke, recent episodes of illness, maternal education and nutrition, and other potentially confounding factors. RESULTS: Analysis shows that prevalence of moderate-to-severe anaemia was significantly higher among children in households using biofuels than among children in households using cleaner fuels (RRR = 1.58; 95% CI: 1.28, 1.94), independent of other factors. Prevalence of severe stunting was also significantly higher among children in biofuel-using households (RRR = 1.84; 95% CI: 1.44, 2.36). Thirty-one per cent of moderate-to-severe anaemia and 37% of severe stunting among children aged 6-35 months in India may be attributable to exposure to biofuel smoke. Effects on mild anaemia and moderate stunting were smaller, but positive and statistically significant. Effects of exposure to tobacco smoke on anaemia and stunting were small and not significant. CONCLUSIONS: The study provides a first evidence of the strong association between biofuel use and risks of anaemia and stunting in children, suggesting that exposure to biofuel smoke may contribute to chronic nutritional deficiencies in young children.

Effects of vitamin A supplementation on child mortality: evidence from Nepal's 2001 Demographic and Health Survey.

OBJECTIVE: To assess the effect of Nepal's vitamin A supplementation programme on child mortality at age 12-59 months. MATERIALS AND METHODS: Logistic regression, applied to retrospective data from Nepal's 2001 Demographic and Health Survey. RESULTS: After a number of potentially confounding variables are controlled, the effect of 100% community-level vitamin A coverage since the child's birth, relative to no coverage, is to reduce the odds of dying at age 12-59 months by slightly more than half (OR = 0.47, P = 0.03). CONCLUSIONS: The estimated beneficial effect of vitamin A supplementation on child mortality is larger than that found in most earlier clinical studies. This larger effect may be due mainly to the other health-related activities undertaken by the female community health volunteers who distribute vitamin A capsules.

Effect of iron supplementation during pregnancy on birthweight: evidence from Zimbabwe.

BACKGROUND: Iron deficiency in pregnant women has been shown to reduce the oxygen supply to the fetus, cause intrauterine growth retardation, and increase the risk of premature delivery and reduced birthweight. Yet the effects of iron supplementation programs on pregnancy outcomes are not well documented for developing countries. OBJECTIVE: To examine the relation between iron supplementation of mothers during pregnancy and children's birthweight using data from a national population-based survey in Zimbabwe. METHODS: The analysis uses information on 3559 births during the five years preceding the 1999 Zimbabwe Demographic and Health Survey. The effect of iron supplementation during pregnancy on birthweight was estimated by multiple regression, controlling for potential confounding effects of prenatal care, child's sex and birth order, mother's education and nutritional status (measured by body-mass index), household living standard, smoke exposure, and other variables. RESULTS: Babies born to mothers who received iron supplementation during pregnancy were 103 g heavier (95% confidence interval, 42-164; p = .001), on average, than babies born to mothers who did not receive iron supplementation during pregnancy. The difference was 64 g (95% confidence interval, 2-125; p = .043) for children whose birthweights were taken from health cards and 163 g (95% confidence interval, 44-281; p = .008) for children whose birthweights were reported by their mothers. CONCLUSIONS: Iron supplementation during pregnancy is associated with significantly higher birthweight, independent of other pregnancy care factors, mother's nutritional status, smoke exposure, and a number of demographic and socioeconomic factors. Prenatal iron supplementation programs can improve pregnancy outcomes and promote child survival in developing countries.

Cooking smoke and tobacco smoke as risk factors for stillbirth.

Smoke from biomass combustion produces some of the same pollutants found in tobacco smoke and ambient air, yet only one study to date has linked cooking with biomass fuels to increased risk of stillbirth. The mechanisms by which biomass smoke may cause stillbirth are through exposure to CO and particulates in biomass smoke. Using information on 19,189 ever-married women aged 40-49 included in India's 1998-99 National Family Health Survey, we examined the association between household use of biomass fuels (wood, dung, and crop residues), tobacco smoke (both active and passive), and risk of stillbirth. Data were analyzed using binary and multinomial logistic regression after controlling for several potentially confounding factors. Results indicate that, with other factors controlled, women who cook with biomass fuels are significantly more likely to have experienced a stillbirth than those who cook with cleaner fuels (OR= 1.44; 95% CI: 1.04, 1.97). Women who cook with biofuels are twice as likely to have experienced two or more stillbirths as those who cook with cleaner fuels (RRR= 2.01; 95% CI: 1.11, 3.62). The adjusted effect of active tobacco smoking is also positive (OR = 1.23) but not statistically significant. No effect of passive smoking was found, nor was there evidence of any modifying effects of tobacco smoking.

Recent trends and components of change in fertility in Nepal.

The objectives of this article are, first, to provide improved estimates of recent fertility levels and trends in Nepal and, second, to analyse the components of fertility change. The analysis is based on data from Nepal's 1996 and 2001 Demographic and Health Surveys. Total fertility rates (TFR) are derived by the own-children method. They incorporate additional adjustments to compensate for displacement of births, and they are compared with estimates derived by the birth-history method. Fertility is estimated not only for the whole country but also by urban/rural residence and by woman's education. The own-children estimates for the whole country indicate that the TFR declined from 4.96 to 4.69 births per woman between the 3-year period preceding the 1996 survey and the 3-year period preceding the 2001 survey. About three-quarters of the decline stems from reductions in age-specific marital fertility rates and about one-quarter from changes in age-specific proportions currently married. Further decomposition of the decline in marital fertility, as measured by births per currently married woman during the 5-year period before each survey, indicates that almost half of the decline in marital fertility is accounted for by changes in population composition by ecological region, development region, urban/rural residence, education, age at first cohabitation with husband, time elapsed since first cohabitation, number of living children at the start of the 5-year period and media exposure. With these variables controlled, another one-third of the decline is accounted for by increase in the proportion sterilized at the start of the 5-year period before each survey.