Hello dear I understand your concern Pregnancy will occur when you did unprotected sex during fertile phase of period. But I think you did sex just day before period date and got period on next day after sex. You got period for 4 days. Pregnancy is not possible in presence of period because absence of period is most common and confirmatory sign of pregnancy. So there is no chance of pregnancy. Avoid stress, take healthy diet, drink plenty of water and do regular exercise Hope this may help you Contact further if follow up needed Best regards Dr. Sagar