Hallow Dear, Dydrogesterone is a retroprogestational medicine. If the periods are delayed, these type of medicines were given in older days to confirm the diagnosis of pregnancy when clinically the diagnosis was dubious. In non pregnant delayed menses, the withdrawal bleeding used to appear within 4-7 days. Now a days, to confirm the diagnosis of early pregnancy, we perform hormonal assessment by Pregnancy test on urine or Beta hCG test on blood. At 4 months duration of pregnancy, in fact, no test is required to confirm the pregnancy. At this stage, the pregnant uterus can be easily palpated from the abdomen clinically. Moreover, if at all required, ultrasonography will give direct visual evidence of pregnancy. However, Dydrogesterone is a Progestational medicine. In cases of unstable pregnancy, we do give progesterone preparations to stabilize the pregnancy. This medicine, that too in single dose, will not cause any ill effects on the baby. However, my advice would be to go for ultrasonography which not only will confirm the diagnosis of pregnancy, but in addition will provide the information about the growth and normalcy of the baby. I hope this will guide you appropriately. Dr. Nishikant Shrotri