Precautions for medication during pregnancy

There are often patients with pharmaceutical clinic consultation. Can I take medicine when I get sick suddenly during pregnancy?How long does it take for children after taking medicine?Will it affect the child if you are pregnant?Fan Jie, deputy director of Fan Jie from Shanghai First Maternal and Infant Health Hospital, gave detailed answers.

Time of medication

The effect of drugs on the fetus is different at different stages of pregnancy. In short, it can be roughly divided into three stages:

(1) Non-sensitive period: 1-2 weeks after fertilization, that is, 14-28 days of the last menstruation.During this period, it was just a fertilized egg, a cell group, and there was no differentiation and development of organizational organs.Even if there is adverse effects after using the medicine, the incidence of birth defects is generally not increased. Once there is an impact, the embryo will stop developing. This is the well -known theory of "all or no".

All: That is, the effect of drugs on embryos, killing cell groups, causing natural miscarriage, and no birth defects.

None: that is, the drug does not affect the embryo, and the cell cluster can continue to differentiate growth and development.

Most drugs are suitable for the theory of "all or no", but it should be noted that there are really a few special drugs that do not conform to this theory.The proven drugs are: Vaccopes of Libaweilin, Different Vitamin A, preventing measles, rubella, mumps, and mumps.

(2) Sensitive period: 3-9 weeks after fertilization, this period is formed by the acceleration differentiation of various embryo organs. It is very vulnerable to external factors such as drugs.

(3) Low sensitivity period: 10-38 weeks after fertilization. At this time, the main organs of the fetus have basically formed, and the sensitivity of drugs is reduced.The effect of drugs on the fetus is mainly manifested as abnormal function or poor survival after birth.

Types of drugs

Different drugs act on different tissue organs, and have different terators.According to the impact of animal experiments and clinical drug experience on fetal teratogenic, the US Food and Drug Administration (FDA) divides the harmful level of drugs to the fetus into 5 levels: A, B, C, D, and X.

In June 2015, the FDA released new drug label requirements for pregnancy, prescription and lactating identification rules PLLR, requiring drug manufacturers to include the risks and benefits of prescription drugs and biological products during pregnancy and breastfeeding in the drug manual provided by them.Information, including "risk overview", "clinical precautions" and "data support".Because the pharmaceutical instructions have not been revised, the fifth classification is still widely used in clinic.

A -level

Human control studies have shown harmless and have confirmed that such drugs have no adverse effects on fetuses.Commonly used are: left norexorine, folic acid and most vitamin drugs.

Level B

Animal experiments have proven that there is no harm to fetuses, but there is no research on human beings; or animal experiments have proven to have a bad role, but no adverse effects are found in the research of human beings in a good control group.For example: penicillin and most cephalosporin drugs.

C -level

Danger cannot be ruled out.Animal experiments may be harmful or lack of research on the fetus.Human beings still lack related research. Only after weighing the benefits of pregnant women is greater than the harm to the fetus, it can be used.For example: Mossian husaccharide, Loss Floxacin, Fluonazole.

D -level

It is harmful to the fetus.But despite this, pregnant women must be used, and it is absolutely beneficial after medication (such as to save the life of pregnant women).For example: Di Xiyu, Mino Circle, Eber Satan.

X -level

Disabled during pregnancy.The experience of drug research on animals and humans or human medication shows that drugs are harmful to the fetus, and the application of this type of drugs for pregnant women is not beneficial to patients who are used for pregnancy or possible pregnancy.For example: Libavirin, Saraidamine, and Avideline A acid.

Class A and B are relatively safe medication during pregnancy. Class C and D should be used after weighing the advantages and disadvantages.

Drug half -life

After the drug enters the human body, it is in a dynamic process.In other words, after the drug is absorbed, it will constantly remove from the body.We usually measure the removal time of the drug in the half -life.Simply put, the half -life is the time required for the drug concentration in human plasma.

After stopping the drug, most drugs will be completely cleaned after 5-7 half-half period.At this time, no drugs will affect children and can continue to prepare for pregnancy.

For example, the half-life of the acetaminophenophenophenophenophenophenophenophenophenophenophenophenophenophenophenophenopopicopathy is 1-3 hours, and it can be cleared one day after stopping the drug.The half -life of the slow release preparation is about 6 hours, and it can be completely cleared after 2 days.

However, there are also some drugs that have been stored in the body for a long time, and have clear reproductive toxicity. It cannot be judged simply in the half-life. After medication, it is necessary to strictly take 3-6 months to get pregnant.For example, vaccines of different vitamin A, Libaweilin, preventing measles, rubella, mumps, and mumps.


Putting the toxicity of the dosage is unscientific.Occasionally, taking one grain and long -term medicine on the end of pregnancy is also completely different.Most drugs have a threshold effect, that is, if the dose of the drug is lower than the teratogenic dose, it will generally not increase the probability of birth defects.However, it is not possible to rule out the adverse effects that individual drugs may bring in a small amount.

Medicine during pregnancy

Medication during pregnancy is generally divided into two cases.

The first one has not yet reached the ovulation period.If you are sick at this time, you should seek medical treatment early, treat early, and heal as soon as possible.At the same time, he told the doctor that he was preparing for pregnancy, and asked him to avoid using some drugs that stayed in the body for long time, such as different vitamin A. Libavirin.

The second has passed the ovulation period.Then it is likely to be conceived at this time, but because the gestational week is too small, it cannot be found.For this situation, medication should be more cautious.Neither the medication, nor the sickness, and relying on yourself.Because compared with the adverse effects of medication, if some diseases are not treated, it will be more harmful to mothers and fetuses.


In general, the following aspects need to be paid attention to medicine during pregnancy:

1. Try to use single medicine treatment to avoid combined medication.

2. Try to choose the old drugs with long clinical use.

3. Try to use the minimum effective and safe dose, and the shortest effective course of treatment.

4. Both couples with chronic diseases should communicate with the attending doctors before pregnancy, switch to drugs that have less affected fetuses, and do not choose drugs by themselves.

Of course, the specific situation must be analyzed in detail. You can seek the help of a professional clinical pharmacist. We will evaluate the risk of medication during pregnancy based on the nature of the drug, the time of medication, the dosage and duration of use, and keep driving for your health.convoy.

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