The regimens are as follows : Group 1 : 200,000 IU VAS at < 3 d and placebo at 6weeks postpartum ; Group 2 : placebo at < 3 d and 200,000 IU VAS at 6weeks postpartum ; Group 3 : 200,000 IU VAS , both at < 3 d and 6weeks postpartum ; Group 4 : placebo , both at < 3 d and 6weeks postpartum .