# Table 2 The birth weight, birth week and gender of children with their mothers prenatally exposed to FHS (first hand smoke) and SHS (second hand smoke) in a rural area of Shanghai in the year of 2018, China

Variables for the children Total condition Mother with prenatal FHS exposure Mother with prenatal SHS exposure
Yes (n = 81) No (n = 8505) Yes (n = 1785) No (n = 6801)
Birth weight (g), mean (SD)†‡ 3315.52 (497.16) 3149.38 (481.03) 3317.10 (497.08) 3263.18 (479.23) 3329.25 (500.89)
Birth weight (g), median (IQR)†‡ 3350 (3000–3650) 3150 (2950–3500) 3350 (3000–3650) 3300 (3000–3570) 3350 (3000–3650)
Birth weight, n (%)†‡
<2500 g 403 (4.69) 10 (12.35) 393 (4.62) 149 (8.35) 254 (3.73)
≥ 2500 g 8183 (95.31) 71 (87.65) 8112 (95.38) 1636 (91.65) 6547 (96.27)
Birth week, mean (SD) 38.61 (2.39) 38.77 (2.43) 38.61 (2.39) 38.62 (2.06) 38.61 (2.47)
Birth week, median (IQR) 39 (38–40) 39 (38–40) 39 (38–40) 39 (38–40) 39 (38–40)
Birth week, n (%)
<37 weeks 850 (9.90) 9 (11.11) 841 (9.89) 174 (9.75) 676 (9.94)
≥ 37 weeks 7736 (90.10) 72 (88.89) 7664 (90.11) 1611 (90.25) 6125 (90.06)
Gender of the children
boy 4595 (53.52) 41 (50.62) 4554 (53.54) 931 (52.16) 3664 (53.87)
girl 3991 (46.48) 40 (49.38) 3951 (46.46) 854 (47.84) 3137 (46.13)
1. SD standard deviation
2. IQR interquartile range
3. the differences in birth weight of the children between mothers with prenatal FHS exposure and without prenatal FHS exposure was statistically significant (P < 0.01)
4. the differences in birth weight of the children between mothers with prenatal SHS exposure and without prenatal SHS exposure was statistically significant (P < 0.01)