I don't know about the manufacturers of vitamin supplements But I do know
that the Institue of Medicine's recommendations in "Nutrition During
Pregnancy" and "Nutrition During Lactation" published in 1991 did not
recommend routine supplements, and instead urges mothers to get their
vitamins from a decent diet. The Implementation guidelines are useful for
pregnancy but a bit sparse on lactation.
Linda Smith, BSE, FACCE, IBCLC
Private practice, Dayton OH