Table 1

Basic characteristics and urinary Pb concentrations (μg/g creatinine) of the 7290 pregnant women

CharacteristicsN (%)Median (IQR)P values
Pb (μg/g creatinine)
Total72903.44 (2.30–5.64)
Maternal age (years)0.43
 <25805 (11.0)3.37 (2.27–5.52)
 25–293985 (54.7)3.49 (2.32–5.77)
 30–342011 (27.6)3.40 (2.29–5.47)
 ≥35489 (6.7)3.41 (2.15–5.94)
Education background (years)0.63
 ≤91001 (13.7)3.45 (2.40–5.63)
 9–121389 (19.1)3.47 (2.35–5.56)
 >124898 (67.2)3.42 (2.26–5.66)
 Missing2 (0.03)5.69 (3.50–7.90)
Family income(¥/year)0.37
 <50 0003021 (41.4)3.52 (2.31–5.75)
 ≥50 0004148 (56.9)3.39 (2.28–5.60)
 Missing121 (1.7)3.50 (2.38–5.83)
Parity0.43
 primiparous6159 (84.5)3.45 (2.30–5.66)
 multiparous1131 (15.5)3.38 (2.26–5.59)
Prepregnancy BMI (kg/m2)0.10
 <18.51527 (20.9)3.47 (2.27–5.77)
 18.5–23.94832 (66.3)3.41 (2.29–5.56)
 ≥24910 (12.5)3.60 (2.39–6.04)
 Missing21 (0.3)3.87 (2.07–8.12)
Passive smoking during pregnancy0.07
 Yes1670 (22.9)3.30 (2.29–5.32)
 No5620 (77.1)3.47 (2.30–5.71)
Pregnancy-induced hypertension0.08
 Yes286 (3.9)3.26 (2.18–5.21)
 No7004 (96.1)3.44 (2.30–5.66)
Gestational age (weeks)<0.01
 <37291 (4.0)3.99 (2.62–7.54)
 ≥376999 (96.0)3.42 (2.29–5.60)
Infant gender0.02
 Male3890 (53.4)3.48 (2.34–5.78)
 Female3400 (46.6)3.40 (2.25–5.52)
PROM881 (12.1)3.88 (2.55–6.59)0.47
 Preterm PROM147 (2.0)3.96 (2.63–7.67)
 Term PROM734 (10.1)3.87 (2.54–6.34)
  • BMI, body mass index; Pb, lead; PROM, premature rupture of membranes.