sábado, 14 de febrero de 2009

Maternal exposure to folic acid antagonists and placenta-mediated adverse pregnancy outcome


The article is "Maternal exposure to folic acid antagonists and placenta-mediated adverse pregnancy outcomes", and was published in CMAJ on the 2 December issue

What is already known about this topic?
Drugs known as folic acid antagonists (some of which are prescribed very often, such as trimethoprim-sulfamethoxazole and some anti-convulsivant drugs) are associated, in pregnant women, with an increased risk of fetal abnormalities, namely neural tube defects, cardiovascular defects, urinary tract defects and oral clefts.

What does this article add?
Besides the already known effects of folic acid antagonists in terms of fetal morbility, this study showed that this class of drugs is associated with an increased risk of pre-eclampsia, placental abruption, intra-uterine growth restriction and fetal death. This association is of the dose-response type. These risks seem to be superior in the case of severe forms of pre-eclampsia and intra-uterine growth restriction.
Exposure during pregnancy to folic acid antagonists seems to be superior in younger women, with lower parity, and those receiving social assistance.

What implications does this article have for GP trainees/Family Medicine residents?
This study questions the current classication of the Food and Drug Administration (FDA) about the use of drugs in pregnancy, since the authors consider that folic acid antagonists should be reclassified as belonging to category D rather than category C.
GP trainees in Portugal have to undertake a compulsory Obstetrics rotation during their vocational training program, and they also do the follow-up of pregnant women in the practice. On many occasions, they must make decisions regarding intercurrent health problems during pregnancy or concerning co-morbidities, whereby they may have to consider resorting to folic acid antagonists. Therefore, it is important that GP trainees become aware that these drugs should, in general, be avoided during pregnancy, to consider alternative drugs, and that they should adequately inform pregnant women of the risks associated with taking folic acid antagonists.

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