As part of a 10-12 wk feeding trial , pregnant ( 26-29 wk gestation ; n = 26 ) , lactating ( 5 wk postpartum ; n = 28 ) , and control ( nonpregnant , nonlactating ; n = 21 ) women consumed vitamin B-12 amounts of 8.6 g/d [ mixed diet ( 6 g/d ) plus a prenatal multivitamin supplement ( 2.6 g/d ) ] .