Pregnancy and terratogens Flashcards
What is a teratogen? What are some examples teratogenic agents?
Any agent that can disturb the development of an embryo or fetus: Can cause birth defect(s) or can halt the pregnancy altogether.
Examples are drugs, radiation, chemicals and maternal infectious agents.
What factors have effects on the outcome of teratogen exposure?
The type of teratogen.
Gestational age at exposure.
Dose and duration of exposure.
Variable vulnerability.
What are the different FDA classifications of drug use in pregnancy?
Class A – Known to be safe for use in pregnancy (Folic acid, FeSO4).
Class B – Not known to be unsafe in pregnancy (Ampicillin, Cephalosporins).
Class C - Sometimes the medicine may still help the human mothers and babies more than it might harm (Fluoxetin, Fluconazole).
Class D – Known to cause harm, but benefits may outweigh harm (Anti-epileptics, Lithium, cancer chemotherapy, Warfarin).
Class X – Contra-indicated in pregnancy (Thalidomide, Isotretinoin).
What are teratogenic effects of ACE-inhibitors?
Severe disturbance of fetal and neonatal renal function, such as oligohydramnios, pulmonary hypoplasia, and long-lasting neonatal anuria.
What are teroatogenic effects of anti-epileptic drugs? Why are anti-epileptic drugs still used in pregnancy?
Neural tube defects (spina bifida), cardiac malformations, and urinary abnormalities.
The risk of harm due to uncontrolled epilepsy is far higher (and includes possible maternal death).
What is fetal warfarin syndrome?
Nasal hypoplasia and skeletal abnormalities including
short limbs and digits (brachydactyly), and stippled epiphyses (Chondrodysplasia
punctata).
In patients with mechanical heart valves anticoagulant are necessary to prevent clotting. However, use of Warfarin during pregnancy may harm the fetus. How should a situation like this be handled?
Use Warfarin in only the second trimest and LMWH in first and third trimester. (LMWH cannot replace Warfarin as clotting protection is not as good.)
What are possible teratogenic effects of lithium? What is lithium used to treat?
Cardiac malfortmations.
Used to treat bipolar disorder.
If a woman is in need of chemotherapy, but is pregnant it is recommended to postpone the treatment for a while. How long?
Until week 14. (The risk of severe problems for the fetus are low and pregnancy termination is not needed.)
During pregnancy, what form of alcohol consumption is the most risky?
Binge drinking in the first trimester.
What are known teratogenic effects of alcohol?
Small for gestational age (SGA).
Microcephaly.
Fetal alcohol syndrome (FAS)
Smoking/tobacco use is a known teratogen. What is the pathophysiological explanation?
Carbon monoxide binds irreversibly to hemoglobin and makes it incapable of transporting oxygen .
Nicotine causes arteriolar spasm.
What are teratogenic effects of tobacco use/smoking?
It gives increased risk of:
Small for gestational age (SGA).
Fetal growth restriction.
Placental abruption.
What are teratogenic effects of heroin/cocian?
Known to cause intense vasospasm.
Increases the risk of SGA, intrauterine growth restriction and placental abruption.
(Often co-exposure to other agents (alcohol, tobacco).) Preterm labor (17.4%), placental abruption (17.3%), abnormal fetal monitoring (15.3)%, and meconium-stained fluid (25%).
When is the fetus most sensitive to ionizing radiation?
Between week 8 and 15.
