Sreeramareddy et al. BMC Public Health 2011, 11:403 http://www.biomedcentral.com/1471-2458/11/403 Table 4 Univariate analyses of size at birth with type of fuel and other variables Variable Low birth weight (n = 9650) Normal birth weight (n = 37489) Unadjusted Odds ratios (95% CI) Type of fuel Low Pollution Fuels 2016 10758 1 High Pollution Fuels 7634 26731 1.41 (1.27, 1.55) Gender of the baby Male 4763 19741 1 Female 4887 17748 1.13 (1.07, 1.20) Birth order 1 3166 11437 1 2 2532 10581 0.89 (0.83, 0.96) 3 1527 6233 0.94 (0.85, 1.03) ≥ 4 2485 9238 0.97 (0.89, 1.06) Mother’s age at child birth ≤ 24 8194 31490 1 25-34 988 4499 0.90 (0.80, 1.01) 35-49 33 126 0.94 (0.46, 1.94 ) Wealth Index Poorest 2080 6345 1 Poorer 2023 6679 1,60 (1.42, 1.81) Middle 2095 7358 1.51 (1.34, 1.70) Richer 1929 8485 1.41 (1.25, 1.58) Richest 1523 8442 1.18 (1.05, 1.32) Type of residence Urban 3170 14876 1 Rural 6480 22613 1.22 (1.11, 1.34) Mother’s religion Hindu 6763 25540 1 Muslim 1606 6247 0.98 (0.88, 1.1) Christian 770 4029 0.76 (0.63, 0.92) Others 369 1242 1.18 (0.97, 1.42) Mother’s Body Mass Index ≤18 2724 8723 18-23 5298 20209 0.87 (0.82, 0.94) 23-28 1055 5577 0.64 (0.57, 0.72) 28-40 245 1363 0.63 (0.50, 0.80) Maternal haemoglobin level (adjusted for altitude) in mg/dl * 137.8 148.5 0.998 (0.997,0.999) Mother’s education No education 4468 14963 Primary 1491 5285 Secondary 3244 14133 Higher 447 3554 Maternal smoking No 9455 36937 Yes 192 536 * 44482 women had undergone haemoglobin testing. Median = 117 (Q1=105, Q3=128). 1 0.96 (0.88, 1.07) 0.83 (0.76, 0.89) 0.55 (0.46, 0.65) 1 1.43 (1.11, 1.86) Page 6 of 10 p-value < 0.0001 < 0.0001 0.014 0.592 0.390 0.711 0.980 <0.0001 < 0.0001 < 0.0001 0.0011 < 0.0001 0.748 0.011 0.059 0.0006 0.0001 0.0170 0.001 0.094 < 0.0001 < 0.0001 0.0067