The use of medication at 4 weeks of pregnancy may have an effect on the fetus, but it may also have no effect and be able to continue the pregnancy. The use of drugs by pregnant women can directly or indirectly affect the fetus, especially in the early stage of embryonic differentiation, it is important to use drugs under the guidance of a doctor with indications to avoid unnecessary use of drugs. At 4 weeks of pregnancy that is, the fertilized egg implantation period, at this time the effect of medication on the embryo for all or nothing, that is, toxic drugs to the embryo will lead to embryonic dysplasia, miscarriage, or the drug does not affect the development of the embryo, no abnormality. The use of drugs during pregnancy should follow the use of drugs must have a clear indication, under the guidance of the doctor to choose safe and effective drugs, try to choose to use drugs alone, avoid the use of combined drugs, and strictly control the dose and the time of use of drugs.