Hi, a brown coloured spotting usually indicates the presence of old collected blood in the genital tract which may be of vaginal, cervical or more likely placental origin. Tab gestrenol does help in sustainence of pregnancy but only if it s viable. A previous blighted ovum indicates a likelihood of some genetic defect in that embryo and is less likely to have any negative effect on this pregnancy. Tab folic acid 5mg once a day taken everyday for first 3 months of pregnancy or has been shown to lower risk of genetic defects in the foetus. You need to visit your gynaec and get an ultrasound done to check the wellbeing of the embryo.