SFTPB and spontaneous preterm birth: The SPB risk was increased to 1.65 (95% CI: 1.04–2.62, p = 0.035) in the highest Mn level (third tertile) in the third trimester, especially in normal-weight women (OR: 2.07, 95% CI: 1.18–3.61, p = 0.011) or non-premature rupture of membrane (PROM) women (OR: 3.93, 95% CI: 2.00–7.74, p < 0.001).