Data and Descriptive Statistics

children’s health outcomes. Section V discusses policy implications and offers some conclusions.

II. Data and Descriptive Statistics

This analysis uses data from three waves of the India NFHS 1992 1993, 19981999, and 20052006. The NFHS is a survey of representative house- holds covering states and territories of India containing approximately 99 percent of its population. The survey structure corresponds to the typical structure of demo- graphic and health surveys DHS conducted in several other countries. Our main sample contains information on 45,279 children from the 19921993 round; 30,984 children from 19981999 round; and 48,679 children from 20052006 round of the India NFHS. 2 These children were residing correspondingly in 33,032, 26,056, and 33,968 households. The NFHS uses three types of questionnaires: The household questionnaire col- lects information on the family structure and background, and on various character- istics of household members. The woman’s questionnaire is administered to women aged 15 to 49 and covers dates and survival status of all births, current pregnancy status, childbearing intentions, and childcare practices. The village questionnaire gathers information on the village area and population.We use the constructed house- hold wealth index as a measure of household welfare. The descriptive statistics for the main variables used in this paper are shown in Table 1. We focused our analysis on the age-adjusted measure of height-for-age HAZ, which reflects children’s development relative to a reference population of well- nourished children World Health Organization 2006. 3 The height-for-age stunting is an indicator of the long-term effect of malnutrition Dibley et al. 1987. For comparability between the rounds of NFHS, we restricted our sample to children less than 36 months of age. Malnutrition is highly prevalent in India. According to NFHS data, about 80 percent of children under the age of three were underweight in 1992, with minimal changes in 1998 and 2005. In 1992, 72 percent of boys and 70 percent of girls were stunted. 4 The proportion of stunted children had decreased to 65 percent by 2005. The overall averages of HAZ rose over the years for both boys and girls. The average 2. The number of observations in the 19981999 round is smaller because NFHS-2 collected height and weight information only for the last two children, under three years of age, of ever-married women who were interviewed. 3. The analysis of relation of month of birth and weight-for-age WAZ z-scores is presented in a working paper version of this paper Lokshin and Radyakin 2009. Across rounds of NFHS, about 10 percent of eligible children were not measured, either because the children were not at home, or because their mothers refused to allow the measurements Lokshin, Das Gupta, and Ivaschenko 2005. We find no relationship between this attrition and the seasonality of birth, gender, or type of the family results are available from authors. 4. A child is considered to be mildly stunted if its HAZ is from ⳮ1 to ⳮ2 standard deviations SD from the mean. Children with HAZ from ⳮ2 to ⳮ3 SD are considered to be moderately stunted, and children with HAZ less than ⳮ3 are considered severely stunted. HAZ had risen for boys from ⳮ1.9 in 1992 to ⳮ1.5 in 2005. Girls experienced similar improvements in health outcomes between 1992 and 2005. The distributions of births by calendar months by gender and for urban and rural samples are presented in Figure 1. 5 The proportions of boys and girls born in each month are similar. The highest birth rates are registered in August, September, and October—these children were conceived in winter. The fewest children were born during the winter months of December, January and February—these children were conceived in spring. The wedding season in India, which falls in the months from November to February could partially explain this seasonality of birth Medora 2003. Figure 2 shows the proportion of children, among all children born in a particular month, who died before the age of three years. The incidence of mortality appears to be unrelated to the month of birth of boys and girls. In addition to the data from NFHS, we use historical rainfall data from TS2.1 database supported by the Tyndall Centre for Climate Change Research at University of East Anglia in Norwich, U. K. This database contains monthly meteorological data for the period from 1901 to 2002 at the nodes of a global grid spaced at 0.25 degree latitude and longitude width Mitchell and Jones 2005. We assigned the monthly rainfall data to the districts of NFHS covered in 1992 and 1998 rounds. The effect of the rainfall on children’s health is identified through the variation in the rainfall over the three years for which we observe children in each round of NFHS.

III. Variations of child health outcomes by month of birth