Objective. To investigate the roles of inherited polymorphisms in the MBL2 gene and exposure to viral infection in the development of a range of adverse pregnancy outcomes, including birthweight<10th percentile (small-for-gestational age, SGA), antepartum hemorrhage (APH), pregnancy-induced hypertensive disorders (PIHD), and preterm birth (PTB). Methods. This was a case-control study using DNA from newborn screening cards of 717 cases (babies with at least one of the adverse pregnancy outcomes listed above) and 609 controls, to screen for six polymorphisms within the MBL2 gene. These combine to create haplotypes with high (HYPA), intermediate (LYQA, LYPA), low (LXPA), and defective (HYPD, LYQC, LYPB) circulating MBL2 levels. Results. Significant associations were found between variant MBL2 haplotypes and SGA (LYPA<32 weeks OR 5.37, 95% CI 1.50-17.27), antepartum hemorrhage (LYPA<37 weeks OR 2.29, 95% CI 1.25-4.18), and PIHD (LYQC<32 weeks (OR 17.89, 95% CI 2.20-139.57). Evidence of exposure to infection increased the effect of these associations, (SGA OR 17.00, 95% CI 1.03-252.48; APH OR 5.67, 95% CI 1.73-18.84; PIHD OR 23.80, 95% CI 1.08-1414.76), while no evidence of exposure to infection demonstrated no associations. PTB was significantly associated with the defective HYPD haplotype with evidence of exposure to infection (OR 6.14, 95% CI 1.21-29.89). Conclusions. This research suggests that the combination of fetal MBL2 haplotypes and exposure to in utero viral infection increases the risk of adverse pregnancy outcomes, including PTB, antepartum hemorrhage, small-for-gestational age and PIHD.