From a pharmacological point of view, based on the above dosing time projection, after the drug clearance, the fetus has not yet started skeletal development, you can continue the pregnancy, but if there is a risk of miscarriage or bleeding, do not preserve the fetus. Case sharing Patient situation: Feng, female, 28 years old, pneumonia (unaware of her pregnancy). Medication: Ciprofloxacin Lactate Sodium Chloride Injection 0.2g, IV, 0.2g each time, twice daily for 7 days. After recovering from the disease, she found that her menstrual period did not come and confirmed that she was pregnant after examination. The patient checked the manual and learned that ciprofloxacin affects fetal cartilage development and is contraindicated in pregnant women! Q: To keep or not to keep the baby? How should I answer the patient’s inquiry in this case? I. Proven teratogens in humans Many drugs are associated with fetal abnormalities, but only a portion of drug cases show malformations. The table above lists drugs that have been shown to be teratogenic in humans. II. Teratogenic Sensitive Periods of Human Embryonic Development After fertilization of the egg, the development of the embryo and fetus is divided into three stages: the insensitive period, the sensitive period and the hypersensitive period. 1, insensitive period (early embryo): 14-28 days after the last menstrual period, that is, 0-2 weeks of pregnancy. During this period, the effect of drugs on the embryo is “all or nothing”: either the embryo dies (miscarriage) because of the effects of lethal doses of drugs, or the fetus is not affected by the drugs, which generally does not lead to fetal malformations. 2, sensitive period (embryonic period): 29 days to 70 days after the last menstrual period, that is, 3-8 weeks of pregnancy. This period is the period of fetal organ differentiation, such as the central nervous system (brain), circulatory system (heart), sensory system (eyes, ears), musculoskeletal system (limbs) and so on. During this period, the embryo is most sensitive to drugs and prone to serious malformations. 3.Low sensitivity period (fetal period): 9-38 weeks of pregnancy (11th-40th week of pregnancy). This period is a period of maturation of most tissues and functions. The effects of drugs may be related to growth and function, such as mental development and reproductive function. Three Elements of Medication Risk Assessment in Pregnancy When conducting a risk assessment in pregnancy, you need to know at least the following three issues. 1.Duration of medication use from the last menstrual period? The time between the use of the drug and the last menstrual period for this pregnant woman: 23 days to 29 days. 2.How long is the usual menstrual cycle? The patient’s menstrual cycle is 28 days and relatively regular. Normally, women ovulate 14 days after their last menstrual period. 3, the nature of the drug (the effect of drugs on the fetus)? Ciprofloxacin (quinolone antimicrobial drug), can pass the placental barrier. The U.S. Food and Drug Administration (FDA) pregnancy safety classification is C. Contraindicated in women during pregnancy! Fourth, the case of pregnant women risk assessment 1, the time of the last dose, in the insensitive, sensitive, low-sensitive period of pregnancy 9-38 weeks? This pregnant woman is special, the time of dosing in the last menstrual period after 23 days ~ 29 days. The last time to use the drug in the 29th day after the last menstrual period, across this 28 days within the relative safety period. 2.Half-life, reproductive toxicity, toxicity target organ of taking drugs? ① Half-life The half-life of ciprofloxacin is about 4~6 hours. In other words, after 6 half-lives (24~36 hours, about 2 days), ciprofloxacin is basically cleared 99%. The last dose of this pregnant woman was administered on the 29th day after her last menstrual period, which means that the actual exposure time of this pregnant woman to ciprofloxacin was 31 days (29 days + 2 days). ② Reproductive toxicity Animal experiments have not confirmed the teratogenic effects of quinolones. A cohort study of 57 women applying quinolone drugs with 17259 control women did not find an increased risk of congenital anomalies. (iii) Toxic target organs Although animal experiments have not confirmed the teratogenic effects of quinolones, they can cause arthropathy in immature animals. After the formation of a fertilized egg, the musculoskeletal system is initiated to develop during 4.33 weeks to 7 weeks of gestation (38-63 days after the last menstrual period). (See table below.) This pregnant woman was exposed to ciprofloxacin for 31 days, which is still 7 days away from 38 days. Therefore, it can be judged that: since the ciprofloxacin has been cleared from the body, the effect on the fetus will be relatively small or even absent. Assessment recommendations: from the pharmacological point of view of analysis, according to the above time projection of the drug, the drug clearance, the fetus has not yet begun skeletal development, you can continue the pregnancy, but if there is a risk of miscarriage or bleeding, do not keep the baby. WARNING: Women of childbearing age who do not use contraception during sex are advised to undergo a pregnancy test before using antivirals (ribavirin), quinolone antibacterials (levofloxacin, ciprofloxacin, moxifloxacin, etc.), aminoglycoside antimicrobials (amikacin, gentamicin, etc.), and tetracycline antimicrobials (minocycline, etc.)!