There are many factors that threaten the developing fetus. Special recommendations also apply to pharmacotherapy and drug substances that can be safely used.
The FDA (Food & Drug Administration), an American governmental institution that deals, inter alia, with the control and authorization of medicines in the United States, classifies medicinal substances that take into account the safety of their use. And so we distinguish the following categories:
Category A
Substances classified in this group are considered safe, and clinical trials conducted in pregnant women have not shown harmful effects of these drugs on the fetus.
(vitamins B, C, D and E in the smallest recommended doses)
B category
The safety of substances placed in this group has not been confirmed
in studies involving pregnant women, and only on animal models.
(including paracetamol, vitamin A in small doses, loratadine, clotrimazole)
Category C
There are medicinal substances that have been shown to be harmful to the fetus in animal studies. These drugs are used only in cases when therapeutic benefits far outweigh the risk of adverse reactions in the fetus.
(e.g., methyldopa, metoprolol, clemastine)
Category D
Clinical studies have shown that the use of medicinal compounds in this group is a threat to the fetus. These medicines can only be used in pregnant women
in conditions threatening the life of the mother, if medicines from the above categories can not be used.
(acetylsalicylic acid, valproic acid, phenytoin)
Category X
Absolutely contraindicated substances in pregnant women have been classified here,
with proven teratogenic effects. It is also not recommended to use them
in women of childbearing and those planning pregnancy.
(retinoids, thalidomide, coumarin derivatives, methylthiouracil, vitamin D in high doses).
The priority in the pharmacotherapy of pregnant women is to maintain safety, which depends primarily on the duration of treatment, dose, but also on the period of fetal development. The most critical moment of using drugs is the period of organogenesis, which falls on the 14-56 day of pregnancy. Then the embryo is the most sensitive to teratogenic factors.
Nowadays, when access to medicines is becoming easier, patients can buy preparations to relieve pregnancy ailments (pain, heartburn, nausea, constipation, fever) also in supermarkets, drugstores, kiosks or gas stations. According to statistical data, the preparations for which the patients most often reach include non-steroidal anti-inflammatory drugs (NSAIDs). As many as 92.6% of women received at least one preparation without a prescription, and 20% of patients used as many as five different drugs. It is estimated that in the United States as many as 1.5 million women use NSAIDs during fertilization or early fetal development.
Non-selective COX inhibitors with short-term treatment are not teratogenic and can be used without problems in the first and second trimester of pregnancy, however, it has been proven that chronic therapy affects both the mother and the fetus.
In animal studies, it was proved that COX inhibitors with increased affinity to inactivate the COX - 1 isoform in relation to COX - 2 can cause developmental defects, especially of the diaphragm and circulatory system. This is related to the occurrence of COX - 1 in the bud during the formation of the circulatory system. Other studies have shown that the administration of NSAIDs may contribute to an increase in pulmonary pressure, and after the 20th week they increase the risk of premature closure of the ductus arteriosus (Botalla) by 20 weeks. This is due to the fact that COX - 1 and COX - 2 are produced in the endothelium and smooth muscle cells of the Botalla duct. Another negative, although not fully confirmed in the study, is the increased risk of miscarriage. This is probably related to the formation of prostaglandins, mainly prostaglandins E (PGE), which play an important role in embryo implantation, placenta formation, and in maintaining pregnancy.
All of the above test results were obtained on animal models.Therefore, they can not be uncritically extrapolated to people. Unfortunately, control tests on pregnant women are a difficult aspect not only scientific, but above all ethical. Until now, the most accurate and most reliable experiments are observation of pregnant patients using NSAIDs (including salicylates). After the conclusion, there was no statistically significant correlation between NSAID use and an increase in the frequency of miscarriages. Another control carried out in the Scandinavian countries allowed the conclusion that no teratogenic effects were found in women using NSAIDs (including salicylates) in the first and second trimesters of pregnancy.
In conclusion, a pregnant woman is a patient who needs special attention from both the doctor and the pharmacist. In the therapy of pain or cold according to the FDA classification, paracetamol (category B) will be the best choice. However, short-term use of NSAIDs such as ibuprofen, naproxen and ketoprofen is permitted in the first and second trimesters (category B). but not contraindicated since the third trimester (category D). Acetylsalicylic acid, commonly used in the treatment of colds and high fever, has been classified in category D as undesirable due to the high risk of fetal damage.
Source literature:
Niżnik B., Gaweł K., Stanisz B .: Pharmaceuticals - help or threat to pregnant women?
Szałek E., Grześkowiak E .: Safety of pharmacotherapy during pregnancy. 2008; 1: 109-115.
