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Table 1 Distribution of selected characteristics of the study population

From: Exposure to cooking fuels and birth weight in Lanzhou, China: a birth cohort study

Characteristic

LBW

NBW

P

SGA

AGA

P

N (%)

N (%)

 

N (%)

N (%)

Maternal age (years)

      

 <25

164(25.2)

1344(15.7)

 

161(21.6)

1256(16.2)

 

 25–29

227(34.9)

4205(49.0)

 

318(42.6)

3765(48.4)

 

 ≥30

259(39.9)

3032(35.3)

<0.001

267(35.8)

2754(35.4)

<0.001

Highest education level

      

 High school or less

414(63.7)

3230(37.6)

 

399(53.5)

2972(38.2)

 

 College or above

219(33.7)

5196(60.6)

<0.001

333(44.6)

4656(59.9)

<0.001

 Missing

17(2.6)

155(1.8)

 

14(1.9)

147(1.9)

 

Family income (RMB per capita)

      

 <3000

436(67.1)

4233(49.3)

 

452(60.6)

3879(49.9)

 

 ≥3,000

154(23.7)

3525(41.1)

<0.001

216(28.9)

3164(40.7)

<0.001

 Missing

60(9.2)

823(9.6)

 

78(10.5)

732(9.4)

 

Maternal pre-pregnancy BMI (kg/m2)

      

 ≤18.5

135(20.8)

1822(21.2)

 

189(25.3)

1670(21.5)

 

 18.6–23.9

396(60.9)

5645(65.8)

 

445(59.7)

5122(65.9)

 

 ≥24

79(12.1)

843(9.8)

0.078

77(10.3)

732(9.4)

0.010

 Missing

40(6.2)

273(3.2)

 

35(4.7)

251(3.2)

 

Maternal weight gain during pregnancy (kg)

      

 <15

346(53.2)

2541(29.6)

 

313(42.0)

2415(31.1)

 

 15–18.5

132(20.3)

2753(32.1)

 

215(28.8)

2468(31.7)

 

 >18.5

108(16.6)

2973(34.6)

<0.001

171(22.9)

2590(33.3)

<0.001

 Missing

64(9.9)

314(3.7)

 

47(6.3)

302(3.9)

 

Vitamin supplement during pregnancy

      

 No

150(23.1)

1234(14.4)

 

152(20.4)

1124(14.5)

 

 Yes

486(74.8)

7259(84.6)

<0.001

581(77.9)

6564(84.4)

<0.001

 Missing

14(2.1)

90(1.0)

 

13(1.7)

87(1.1)

 

Smoking (Active and passive)

      

 No

489(75.2)

6923(80.7)

 

560(75.1)

6272(80.7)

 

 Yes

161(24.8)

1658(19.3)

<0.001

186(24.9)

1502(19.3)

<0.001

Alcohol during pregnancy

      

 No

641(98.6)

8490(98.9)

 

735(98.5)

7693(98.9)

 

 Yes

2(0.3)

17(0.2)

0.882

2(0.3)

15(0.2)

0.989

 Missing

7(1.1)

74(0.9)

 

9(1.2)

67(0.9)

 

Gestational Diabetes

      

 No

647(99.5)

8513(99.2)

 

743(99.6)

7717(99.2)

 

 Yes

3(0.5)

68(0.8)

0.485

3(0.3)

58(0.8)

0.368

Preeclampsia

      

 No

539(82.9)

8388(97.8)

 

659(88.3)

7582(97.5)

 

 Yes

111(17.1)

193(2.2)

<0.001

87(11.7)

193(2.5)

<0.001

Parity

      

 Primiparous

379(58.5)

6375(74.3)

 

518(69.4)

5734(73.8)

 

 Multiparous

269(41.5)

2208(25.7)

<0.001

228(30.6)

2041(26.2)

0.012

Caesarean section

      

 No

298(45.8)

5473(63.8)

 

400(53.6)

4978(64.0)

 

 Yes

326(50.2)

3058(35.6)

<0.001

335(44.9)

2739(35.2)

<0.001

 Miss

26(4.0)

50(0.6)

 

11(1.5)

58(0.8)

 

Gender

      

 Boy

326(50.2)

4427(51.6)

 

369(49.5)

4067(52.3)

 

 Girl

322(49.5)

4138(48.2)

 

376(50.4)

3693(47.5)

 

 Missing

2(0.3)

16(0.2)

0.498

1(0.1)

15(0.2)

0.133

Ventilation

      

 No

271(41.7)

1646(19.2)

 

249(33.4)

1563(20.1)

 

 Yes

379(58.3)

6935(80.8)

<0.001

497(66.6)

6212(79.9)

<0.001