women s health issues
Safety of Medications During Pregnancy
Introduction
During pregnancy, women may need to take medications to treat new or existing health conditions. Also, certain vitamins are recommended during pregnancy. Before taking any medication (including over-the-counter medications) or Overview of Dietary Supplements (including medicinal herbs), a pregnant woman should consult a doctor. Women currently taking medications and planning to become pregnant should consult a doctor before pregnancy, if possible, to see if those medications need to be stopped or changed. (See also the Medications or other substances taken by a pregnant woman may reach the fetus by crossing the placenta, the same route taken by oxygen and nutrients, which are needed for the fetus's growth and development. However, those that do not cross the placenta may still harm the fetus by affecting the uterus or the placenta. Medications or other substances that a pregnant woman takes during pregnancy can affect the fetus in several ways: No impact on the fetus and its development Act directly on the fetus, causing damage, abnormal development (leading to Overview of Birth Defects ), or death Alter the function of the placenta, usually by causing blood vessels to narrow (constrict) and thus reducing the supply of oxygen and nutrients to the fetus from the mother (sometimes resulting in the baby being underweight and underdeveloped) Cause the muscles of the uterus to contract forcefully, indirectly injuring the fetus by reducing its blood supply or triggering Preterm Labor and delivery Affect the fetus indirectly (for example, medications that lower the mother's blood pressure may reduce blood flow to the placenta and thus reduce the supply of oxygen and nutrients to the fetus) Some medications stay in the body and can have effects after they are stopped. For example,isotretinoin, a medication used to treat skin disorders, is stored in fat beneath the skin and is released slowly over weeks.Isotretinoincan cause birth defects if a woman becomes pregnant within 2 weeks after the medication is stopped. Therefore, women are advised to wait at least 3 to 4 weeks after the medication is stopped before they become pregnant. Some of the fetus's blood vessels are contained in tiny hairlike projections (villi) of the placenta that extend into the wall of the uterus. The mother's blood passes through the space surrounding the villi (intervillous space). Only a thin membrane (placental membrane) separates the mother's blood in the intervillous space from the fetus's blood in the villi. Medications in the mother's blood can cross this membrane into blood vessels in the villi and pass through the umbilical cord to the fetus. How a medication affects a fetus depends on the Stage of fetal development Strength and dose of the medication Permeability of the placenta (how easily substances pass through it) Genetic Makeup and Response to Drugs in the pregnant woman, which affects how much of the medication is active and available Pregnant woman's health (for example, nausea and vomiting may decrease absorption of a medication taken by mouth) Government agencies that oversee drug safety may classify medications based on current knowledge about safety during pregnancy. In the United States, the US Food and Drug Administration (FDA) provides information about drug safety in pregnancy (seeFDA: Medicine and Pregnancy). Knowledge about drug safety in pregnancy is based on research in humans and animals and on side effects that are reported by people who have taken the medication. In general, doctors advise pregnant women about taking a medication based on available research, importance of the medication to the health of the pregnant woman, and whether there are other treatments that have less risk to the pregnant woman or fetus. Medications are given in pregnancy if the benefits outweigh the risks. 