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. 2022 Jul 15;13:39. doi: 10.1186/s13293-022-00443-1

Table 1.

Clinical characteristics for Total biomarker study group (n = 2603) and Nicotine exposure study group (n = 2278)

Maternal and pregnancy characteristics Total biomarker study group (n = 2603) Nicotine exposure study group (n = 2278)
N % N %
Fetal sex
Male 1371 53.0 1201 53.0
Female 1214 47.0 1066 47.0
Gestational age at blood sampling (weeks)*, mean ± SD 19.8 ± 6.2 19.8 ± 6.1
16–17 199 7.7 168 7.5
18 811 31.5 695 30.8
19–20 993 38.6 859 38.1
21–23 573 22.2 532 23.6
Maternal age at enrollment (years), mean ± SD 32.3 ± 4.2 32.4 ± 4.2
 < 30 900 34.5 770 33.8
30–35 1120 43.0 993 43.6
 > 35–40 500 19.2 441 19.4
 > 40 83 3.2 74 3.2
Maternal prepregnancy body mass index (kg/m2), mean ± SD 24.8 ± 3.7 24.8 ± 3.7
Underweight < 18.5 87 3.4 76 3.4
Normal weight 18.5–24.9 1902 74.9 1669 75.1
Overweight 25.0–29.9 405 16.0 361 16.3
Obese ≥ 30.0 145 5.7 115 5.2
Parity (previous deliveries)
0 1694 65.1 1369 60.1
1 717 27.5 717 31.5
 > 1 192 7.4 192 8.4
Country of origin
Norway or Sweden 2020 77.6 2020 88.7
Rest of the world 258 9.9 258 11.3
Education (years)
Preliminary school only (9–10 years) 18 0.7 18 0.8
High school only 230 8.8 230 10.1
Higher education < 4 years 730 28.0 730 32.2
Higher education ≥ 4 years 1289 49.5 1289 56.8
Other 2 0.1 2 0.1
Snus
Never 1762 67.7 1762 77.3
Stopped before pregnancy 343 13.2 343 15.1
Stopped when recognizing pregnancy 160 6.2 160 7.0
Current 13 0.5 13 0.6
Smoking
Never 1762 67.7 1762 77.3
Stopped before pregnancy 404 15.5 404 17.6
Stopped when recognizing pregnancy 97 3.7 97 4.3
Current 15 0.6 15 0.7

N, number; SD, Standard Deviation; %, percentage