Pregnant women require greater amounts. Photo Credit Jupiterimages/BananaStock/Getty Images. According to the Institute of Medicine, men require 400 to 420 mg of magnesium daily while women require 310 to 320 mg. Pregnant or lactating women require slightly greater amounts, approximately 310 to 400 mg, per day.Children require 80 to 240 mg daily, while adolescents require 360 to 410 mg of magnesium.regnant women require greater amounts. Photo Credit Jupiterimages/BananaStock/Getty Images. According to the Institute of Medicine, men require 400 to 420 mg of magnesium daily while women require 310 to 320 mg. Pregnant or lactating women require slightly greater amounts, approximately 310 to 400 mg, per day.