Maternal consumption of dietary methyl donors (DMDs) such as folate, methionine, choline, as well as co-factors including zinc, vitamins B2, B6 and B12 can lead to permanent alterations in the DNA and gene expression of the developing fetus. This study aimed to identify patterns of DMD intake during the second trimester of pregnancy and their associations with infant birth weight, small and large for gestational age (SGA and LGA, respectively). From food sources alone, most pregnant women were below the estimated average requirement for dietary folate equivalent (DFE) (69%) and below the adequate intake measure for choline (99%). Zinc seemed to be the most important nutrient for attaining adequate birth weight. DFE and vitamin B12 were positively associated with birth weight. DFE also reduced the risk for SGA whereas choline increased the risk for LGA. Therefore, DMD intake from food sources during pregnancy may be important to ensure optimal infant birth weight.