Whether or not a toothache medicine taken on the 40th day of pregnancy affects the child is related to the medication taken. If you are taking penicillin or cephalosporin anti-inflammatory drugs, the effect on the fetus is minimal. However, if the medicine taken is a common painkiller, it will affect the growth and development of the child. 40 days of pregnancy belongs to the early stages of pregnancy, is a critical period of fetal development, indiscriminate use of drugs is likely to lead to fetal development retardation, malformation phenomenon, serious and even miscarriage. If you are already taking toothache medication, it is recommended that you have a good pregnancy checkup to observe the growth and development of the fetus, and if there is any abnormality, it should be dealt with as soon as possible. If you have a toothache during pregnancy, you should go to the hospital for a relevant examination to determine the cause of the toothache and then deal with it under the guidance of the doctor, do not blindly take medication. If it is inflammation, you can take anti-inflammatory drugs. However, if the tooth is decayed, root canal treatment should be carried out. Toothache can easily occur during pregnancy because hormonal changes in the body during pregnancy can affect the oral flora. So pay attention to oral hygiene during this time, rinse your mouth with saline every day, and brush your teeth in the morning and evening.