Taking some cold medicines without knowing that you are pregnant may affect the development of the fetus. Cold medicines are categorized in many ways, and if you take cold medicines without knowing that you are pregnant, you need to know the name of the cold medicines, the type of cold medicines, the time of taking the medicines, the dosage of cold medicines, etc., and you need to know specifically the menstrual condition of the patient to estimate the period when you are using the medicines. The time and dosage of the medication are different and will have different effects on the fetus. If you take medication by mistake, you need to go to the hospital as soon as possible for consultation and more professional and personalized guidance.