Skip to main content

Table 1 Socio-demographic characteristics and environmental and dietary exposures of term low birth weight cases and controls

From: Interactive effects of maternal exposure to chemical fertilizer and socio-economic status on the risk of low birth weight

Variable

tLBW Case

Control

\({{\varvec{\chi}}}^{2}\) a

P

N(%)

N(%)

Socio-demographic characteristics

 Maternal age

  < 28

97(54.19)

122(59.80)

  

  ≥ 28

82(45.81)

82(40.20)

1.237

0.268

 Infant sex

  Female

95(53.07)

98(48.04)

  

  Male

84(46.93)

106(51.96)

0.996

0.326

 Parity

  1

83(46.37)

103(50.49)

  

  ≥ 2

96(53.63)

101(49.51)

0.648

0.421

 Maternal BMI (kg/m2)

  < 18.5

8(4.47)

10(4.90)

  

  18.5 ~ 24

111(62.01)

131(64.22)

  

  ≥ 24

60(33.52)

63(30.88)

0.318

0.853

 Village income per capita (RMB/year)

  < 6527b

92(51.40)

98(48.04)

  

  ≥ 6527

87(48.60)

106(51.96)

0.430

0.512

 Individual SES index

  High

74 (41.34)

117(57.35)

  

  Low

105(58.66)

87(42.35)

7.778

0.002

 Maternal occupation

  Others

41(22.91)

59(28.92)

  

  Famers or unemployed

138(77.09)

145(71.08)

1.789

0.181

 Maternal education

  High schools or higher

27(15.08)

36(17.65)

  

  Middle schools or lower

152(84.92)

168(82.35)

0.456

0.500

 Paternal education

  High schools or higher

37(20.67)

35(17.16)

  

  Middle schools or lower

142(79.33)

169(82.64)

0.771

0.380

 Household income (Thousand RMB/year)

  Medium (Min ~ Max)

15 (2 ~ 100)

20 (2 ~ 150)

6.334

0.012

Environmental exposure and lifestyles during pregnancy

 Household chemical fertilizer application

  None

90(50.28)

126(61.76)

  

  Yes

89(49.72)

78(38.24)

5.115

0.024

 Village chemical fertilizer application

  Low

72(43.11)

106(56.68)

  

  High

95(56.89)

81(43.32)

6.499

0.011

 Household pesticide application

  No

173(96.65)

200(98.04)

  

  Yes

6(3.35)

4(1.96)

 

0.525c

 Maternal personal contact with pesticides

  No

157(99.37)

195(97.50)

  

  Yes

1(0.63)

5(2.50)

 

0.234c

 Living distance from highway (m)

  ≤ 1000

45(25.41)

64(31.37)

  

  > 1000

134(74.86)

140(68.63)

1.819

0.177

 IAPCC

  0

80(44.69)

111(54.41)

  

  ≥ 1

99(55.31)

93(45.59)

3.602

0.058

 Maternal active smoking

  No

177(100.00)

197(98.99)

  

  Yes

0(0.00)

2(1.01)

 

0.500c

 Maternal passive smoking

  No

61(34.08)

76(37.52)

  

  Yes

118(65.92)

128(62.75)

0.419

0.518

Dietary exposure during pregnancy

 Meat intake (times/week)

  ≤ 1

125(69.83)

120(59.11)

  

  2~7

54(30.17)

83(40.89)

4.752

0.029

 Eggs or milk intake (times/week)

  < 4

94(52.51)

69(33.82)

  

  4~7

85(47.49)

135(66.18)

13.624

 < 0.001

 Fresh vegetables intake (times/week)

  ≤ 5

114(63.69)

126(61.76)

  

  6~7

65(36.31)

78(38.24)

0.151

0.698

 Fresh fruit intake (times/week)

  < 4

56(31.46)

54(26.47)

  

  4~7

122(68.54)

150(73.53)

1.154

0.283

  1. aWald χ.2 test for categorical variables and Kruskal–Wallis test for continuous variables
  2. bthe median income per capita of the 120 villages
  3. cFisher exact test
  4. tLBW term low birth weight, SES index socio-economic status index, IAPCC indoor air pollution from coal combustion