Anesthesia Choices for Pregnant Women
The dental treatment of pregnant women is a critical concern for many dental professionals. Medications can cross the placenta and potentially cause toxicity or teratogenic effects on the fetus, so extra care is needed during treatment. This article discusses the anesthesia and medication use for pregnant women, providing valuable information for dentists.
Editor: James W. Little (USA)
Choice of Local Anesthetics During Pregnancy
During pregnancy, the use of common local anesthetics like lidocaine and procaine with epinephrine is generally considered safe. Articaine, bupivacaine, and mepivacaine are typically safe but should be used cautiously. Although local anesthetics and vasoconstrictors do cross the placenta, subtoxic threshold doses have not been shown to cause fetal abnormalities. Since the side effects of local anesthetics are related to high doses, it is crucial not to exceed the maximum dose recommended by the manufacturer. Additionally, some topical anesthetics such as benzocaine, dyclonine, and tetracaine can be used cautiously, while topical lidocaine is considered safe.
Choice of Analgesics During Pregnancy
Acetaminophen is the preferred analgesic for use during pregnancy. Aspirin and nonsteroidal anti-inflammatory drugs (NSAIDs) can cause ductus arteriosus constriction, postpartum hemorrhage, and delayed labor. Using these medications, especially in late pregnancy, increases the risk of adverse events and should be avoided or used with caution. The risk of adverse effects is also associated with long-term use, high doses, and strong selective anti-inflammatory drugs like corticosteroids and indomethacin. Most opioids, including codeine, meperidine, and propoxyphene, are linked to various congenital defects and should be used cautiously and only when necessary. The safety of hydrocodone and oxycodone is unclear, and they should be avoided or used cautiously due to potential respiratory effects.
Choice of Antibiotics During Pregnancy
Penicillins (including amoxicillin), erythromycin (except erythromycin estolate), cephalosporins, metronidazole, and clindamycin are generally considered safe for pregnant women and their developing fetuses. Tetracyclines, including doxycycline, should be avoided during pregnancy. Tetracyclines bind to hydroxyapatite, causing tooth discoloration, enamel hypoplasia, inhibited bone growth, and other skeletal abnormalities. Clarithromycin should also be avoided or used cautiously.
Antibiotics and Oral Contraceptives
There is a potential interaction between antibiotics and oral contraceptives. Select antibiotics like rifampin (an anti-tuberculosis drug) can reduce plasma levels of circulating oral contraceptives. This interaction is presumed to occur with other antibiotics, but studies on other antibiotics are less reliable. To address this issue, the American Dental Association’s Council on Scientific Affairs recommends the following for women taking oral contraceptives when prescribed antibiotics:
1. Inform the patient of the potential risk of reduced effectiveness of oral contraceptives due to antibiotics.
2. Advise the patient to discuss alternative non-hormonal contraceptive methods with their physician.
3. Recommend that the patient continues to adhere to their oral contraceptive regimen while taking antibiotics.
Until more conclusive research is available, following these recommendations is prudent. Generally, dentists should treat acute infections regardless of the patient’s pregnancy stage.
Use of Anti-Anxiety Medications During Pregnancy
Few anti-anxiety medications are considered safe during pregnancy. Benzodiazepines, zaleplon, and zolpidem should be avoided. However, single, short-term exposure to nitrous oxide-oxygen (N2O-O2) for less than 35 minutes is not associated with fetal abnormalities or low birth weight. Long-term occupational exposure to N2O-O2 is linked to spontaneous abortion and reduced fertility in humans. Nitrous oxide may inactivate methionine synthase and vitamin B12, altering DNA metabolism, leading to cell abnormalities and birth defects. Therefore, if N2O-O2 is used during pregnancy, the following guidelines are recommended:
1. Minimize N2O-O2 inhalation to 30 minutes.
2. Provide at least 50% oxygen to ensure adequate oxygenation at all times.
3. Increase oxygen at the end of administration to prevent diffusion hypoxia.
4. Avoid repeated and prolonged exposure to nitrous oxide.
5. Since organogenesis occurs early in pregnancy, mid to late pregnancy is a safer treatment period.
Additionally, pregnant dental professionals or assistants should not be exposed to persistent trace amounts of nitrous oxide in the operating room. Using appropriate scavenging systems can help mitigate this issue. Long-term exposure to nitrous oxide for more than 3 hours per week may reduce fertility and increase the risk of spontaneous abortion in female dental healthcare workers, so occupational exposure should be minimized.
Medication Use During Lactation
When lactating women require dental treatment involving medication, there is a concern that the medication may pass into the breast milk and affect the nursing infant. While data providing exact conclusions on drug dosage and effects in breast milk are limited, retrospective clinical studies and empirical observations, combined with known pharmacological pathways, suggest that most medications prescribed to lactating women should not significantly impact milk supply or the infant’s health. Notably, drug excretion into breast milk is usually less than 1%-2% of the maternal dose, making most medications pharmacologically insignificant for the infant.
Certain drugs, including lithium, anticancer drugs, radioactive substances, and coumarin derivatives, should be absolutely avoided during lactation. Besides careful medication selection, lactating women may take medications after breastfeeding and avoid nursing for 4 hours or more to reduce drug concentration in the breast milk.
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