The classic teratogenic period is from day 31 after the last menstrual period (LMP) in a 28-day cycle to 71 days from the LMP. During this critical time, organs are forming, and teratogens may cause overt malformation. Administration of drugs early in the period of organogenesis will affect the organs developing then, such as the heart or neural tube. Closer to the end of the classic teratogenic period, the ear and palate are forming and may be affected by a teratogen.
Before day 31, exposure to a teratogen produces an all-or-none effect. With exposure around conception, the conceptus usually either does not survive or survives without anomalies. If the organism remains viable, organ-specific anomalies do not develop because repair or replacement permits normal development. A similar insult at a later stage may produce organ-specific defects; after the first trimester, chronic exposure may produce growth restriction.
The Food and Drug Administration (FDA) lists five categories of labeling for drug use in pregnancy:
Category A: Controlled studies in women fail to demonstrate a risk to the fetus in the first trimester, and the possibility of fetal harm appears remote.
Category B: Animal studies do not indicate a risk to the fetus, there are no controlled human studies, or animal studies do show an adverse effect on the fetus, but well-controlled studies in pregnant women have failed to demonstrate a risk to the fetus.
Category C: Studies have shown the drug to have animal teratogenic or embryocidal effects, but no controlled studies in women are available or no studies are available in either animals or women.
Category D: Positive evidence of human fetal risk exists, but benefits in certain situations (e.g., life-threatening situations or serious diseases for which safer drugs cannot be used or are ineffective) may make the use of the drug acceptable despite its risks.
Category X: Studies in animals or humans have demonstrated fetal abnormalities, or evidence demonstrates fetal risk based on human experience, or both, and the risk clearly outweighs any possible benefit.
Table..102-1, T§ble.102:2, Table 10.2:3 and Table.102-4 list medications to be avoided in pregnancy. Table 1.0.2:5 lists categories of drugs generally considered safe during breast-feeding.
TABLE 102-1 Therapeutic Agents Commonly Used in Emergency Settings with Known Adverse Effects in Human Pregnancy
Was this article helpful?
If you seriously want know how to get rid of bed bugs, then this may be the most important letter you'll ever read!... Discover How To Solve Your Dilemma In What You Thought To Be Your Dream Vacation And Easily Taking The First Step To Conquer The Bed Bugs Trauma You May Have At This Moment! It doesn't matter, if you have never have any ideas on how to getting rid of bed bugs and how to banish it quickly in the shortest time possible, then this golden guides will show you everything steps you need to take against bed bugs banishing!