Periconceptional maternal supplement intake and human embryonic growth, development, and birth outcomes: the Rotterdam Periconception Cohort.

STUDY QUESTION: Is periconceptional multiple-micronutrient supplement (MMS) use including folic acid (FA) compared to FA use only associated with increased embryonic growth, development, and birth weight in a high-risk population? SUMMARY ANSWER: Women with MMS intake show no significant differences in first-trimester morphological embryo development, but increased first-trimester embryonic growth trajectories and fewer neonates born small for gestational age (SGA), less than the 3rd percentile (