To investigate the impact of carriage of single nucleotide polymorphisms (SNPs) of the Toll-like receptor-4 (TLR4) and of autophagy-related gene 16-like-1 (ATG16L1) in preterm delivery (PTD).A prospective cohort of 145 pregnant women was studied. Women were prospectively followed-up until delivery. Genotyping for rs4986790 (Asp299Gly transition) and rs4986791 (Thr399Ile transition) of TLR4 and for rs2241880 of ATG16L1 was done by PCR-restriction fragment length polymorphism. The primary study endpoint was the impact of carriage of minor alleles of TLR4 on early PTD before gestational week 32. Associations with human chorionic gonadotrophin (hCG) were also analyzed. Peripheral blood mononuclear cells were isolated from 15 healthy women and stimulated for cytokine production.No difference in clinical characteristics was observed between women delivering full term and preterm. The frequency of early PTD was 25% among women carrying minor alleles of TLR4 and 6.8% among women carrying major alleles (P: .032). Odds ratios for PTD were 3.85 among women carrying the GG genotype of rs2241880 and major alleles of TLR4 and 0.26 among carriers of GG genotype and minor alleles of TLR4 (P: .030). The co-presence of GG genotype of rs2241880 and hCG above 70 U/L was an independent variable for PTD. Stimulated production of interleukin-6 was greater among women with GG genotypes of rs2241880.Minor alleles of SNPs of TLR4 predispose to early PTD. The GG genotype of rs2241880 of ATG16L1 is associated with PTD when hCG is supra-elevated.