Drugs effect on the pregnancy

By wisam Gatea Hani

Introduction

• Majority of pregnant women (40 – 90%) are exposed to medications during pregnancy• Many medications are taken without

physicians advice or before recognition of the pregnancy• In general drugs ,unless absolutely

necessary ,should not be used during pregnancy because many can harm fetus .

Cont…

• About 2 to 3 % of all birth defects result from the use of drugs other then alcohol.

• Medications are sometime essential therapy for serious life threatening medical conditions that are superimposed on pregnancy.

Compliance

• Pregnant women tend to comply less than optimally with drug therapy• 39% of women reported noncompliance

predominantly due to hesitation to use drugs during pregnancy

BIRTH DEFECTS

Incidenceof major structural defects (abnormalities) is about 6% of all pregnancies.

3% are caused by drugs or environmental factors/exposure

3% have unknown causes

Cont…

1/2 of the birth defects are obvious at birth.

1/2 of the birth defects aren’t discovered until later in life or discovered during an autopsy

Incidence of minor structural abnormalies is not known.

Drugs taken by a pregnant woman reach the fetus primarily by crossing the placenta, the same route taken by oxygen and nutrients, which are needed for the fetus's growth and development. Drugs that a pregnant woman takes during pregnancy can affect the fetus in several ways:

Ways

They can act directly on the fetus, causing damage, abnormal development (leading to birth defects), or death.

They can 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 the result is a baby that is underweight and underdeveloped.

They can cause the muscles of the uterus to contract forcefully, indirectly injuring the fetus by reducing its blood supply or triggering preterm labor and delivery.

How Drugs Cross the Placental

• Some of the fetus's blood vessels are contained in tiny hair like 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

Cont…Drugs in the mother's blood can cross this

membrane into blood vessels in the villi and pass through the umbilical cord to the fetus.

FDA• The Food and Drug (FDA)classifies drugs

according to the degree of risk they pose for the fetus if they are used during pregnancy. Some drugs are highly toxic and should never be used by pregnant women because they cause severe birth defects. • In general every medication is assigned to

a category. (A,B, C, D or X) based on how safe or risky it is to use during pregnancy

Cont..•Category A:    Adequate and well-

controlled studies have failed to demonstrate a risk to the fetus in the first trimester of pregnancy (and there is no evidence of risk in later trimesters).•Category B:   Animal reproduction

studies have failed to demonstrate a risk to the fetus and there are no adequate and well-controlled studies in pregnant women.

Cont..• Category C:   Animal reproduction

studies have shown an adverse effect on the fetus and there are no adequate and well-controlled studies in humans, but potential benefits may warrant use of the drug in pregnant women despite potential risks.

•Category D:    There is positive evidence of human fetal risk based on adverse reaction data from investigational or marketing experience or studies in humans, but potential benefits may warrant use of the drug in pregnant women despite potential risks

•Category X:  Studies in animals or humans have demonstrated fetal abnormalities and/or there is positive evidence of human fetal risk based on adverse reaction data from investigational or marketing experience, and the risks involved in use of the drug in pregnant women clearly outweigh potential benefits.

Penicillins and Cephalosporins

• Amoxicillin and cephalosporins (category B) are considered safe to use during pregnancy• No increased risk of malformations with

amoxicillin/clavulanic acid (Augmentin) in 2 studies. (category B)

Erythromycin and azithromycin: Category B• Clarithromycin: Category C• Clindamycin: category B• Ciprofloxacin: category C: possibility of

joint malformation (seen only in children) • Tetracyclines: category D

Metronidazole•Mutagenic in bacteria and carcinogenic in

animals• Small number of reports raised suspicion

of teratogenic effect• Category B

Aminoglycosides: ototoxicity: can cause deafness

Sulfonamides: jaundice when given late in pregnancy and possible brain damage (kernictrus).

Local Anesthetics - Lidocaine• Considered relatively safe for use during

pregnancy (category B)•Mepivacane (category C)

Epinephrine• Potential to compromise uterine blood

flow• Studies have failed to demonstrate

adverse fetal effects• Low doses used in dentistry• Avoid inadvertent intravascular injection• Category C

Acetaminophen• “Analgesic of choice” category B.

NSAIDS (including Aspirin and cox II-inhibitors)

• Increased risk of miscarriage?

• Avoid use during late pregnancy (3rd trimester)• Bleeding• Inhibition of prostaglandin synthesis• Prolonged labour• Constriction of ductus arteriosus• Category C but in last trimester category D

Narcotics(Codeine, Oxycodone, etc.)

• Don’t appear to risk of birth defects• Low dose short-term regimens acceptable.

Category CIf used for long period: category D • Respiratory depression• Neonatal withdrawal

Nitrous Oxide (N2O) with O2

• Use during pregnancy somewhat controversial• Inhibits methionine synthetase which can affect

DNA synthesis• Teratogenic in animals• Single brief maternal exposure during pregnancy

unlikely to pose a substantial teratogenic risk• Minimize prolonged use (< 30 minutes, at least

50% O2)

Benzodiazepines

• Category D• Cause cleft palat

Radiation

• In most cases of diagnostic x-rays the fetal radiation exposure is much below the threshold dose of 5 to 10 rad

American Dental Association

• Abdominal exposure during dental radiography is negligible• Recommend that pregnant women postpone

elective dental x-rays until after delivery; however, there are times when an x-ray may be required during pregnancy to help diagnose and treat oral disease (thyroid collar and apron)

Some Drugs That Can Cause Problems During Pregnancy

Category D

Category c

Category c

Category D

Category B

Category D

Vitamins• Folic acid :- Category A • Vitamin A :- Category(A/C dose exceeding RDA recommended dose) • Vitamin C :- Category A/Cdose exceeding RDA recommended dose)• Vitamin E :- Category A/C dose exceeding RDA recommended dose)• Vitamin B:- Category A/Cdose exceeding RDA recommended dose)• Vitamin D :- CategoryC• Vitamin K :- Category C•

Thank you10 / 2 / 2017