Univariable analyses revealed that GDM (OR = 2.97, 95% CI: 1.22~7.22, p = 0.016), higher levels of CRP (OR = 1.30, 95% CI: 1.01~1.67, p = 0.042), SAA (OR = 1.33, 95% CI: 1.03~1.72, p = 0.032), and O3 exposure (OR = 1.23, 95% CI: 1.06~1.43, p = 0.007) were all significantly associated with increased risk of PTB. The gene discussed is CRP; the disease is gestational diabetes.