Choline levels measured in the blood of a newborn baby are about 6 or 7 times higher than in an adult. Because choline needs in pregnancy and lactation are much higher, the pathway for de novo synthesis of choline ramps up to peak production in the third trimester. The key to revving up of this system is estrogen, which dials up the PEMT gene to produce more and more enzyme (PEMT) to crank out more choline in an attempt to meet the needs of the baby. But, is it enough? Despite the enhanced capacity in the last trimester to make choline, the extraordinary demand in the fetus is so high, that invariably the mother's choline supply is depleted, and she needs choline supplementation.

When women in their third trimester were supplemented with choline, it was found that a dose significantly exceeding current recommendations (450mg/day) was needed to meet the high demand of the pregnancy.