For vitamin B12, the U.S. Recommended Dietary Allowance (RDA) for pregnancy is 2.6 µg/day, for lactation 2.8 µg/day. Determination of these values was based on RDA of 2.4 µg/day for non-pregnant women plus what will be transferred to the fetus during pregnancy and what will be delivered in breast milk. However, looking at the same scientific evidence, the European Food Safety Authority (EFSA) sets adequate intake (AI) at 4.5μg/day for pregnancy and 5.0 μg/day for lactation. Low maternal vitamin B12, defined as serum concentration less than 148 pmol/L, increases the risk of miscarriage, newborn low birth weight and preterm birth. During pregnancy the placenta concentrates B12, so that newborn infants have a higher serum concentration than their mothers. What the mother-to-be consumes during the pregnancy is more important than her liver tissue stores, as it is recently absorbed vitamin content that more effectively reaches the placenta. Women who consume a small percentage of their diet from animal-sourced foods or who by choice consume a vegetarian or vegan diet are at higher risk than those consuming higher amounts of animal-sourced foods for becoming vitamin depleted during pregnancy, which can lead to anemia, and also an increased risk that their breastfed infants become vitamin deficient.