Is Dental Anesthesia Safe During Pregnancy?

Pregnancy is an extremely crucial time for each and every woman. Since maternal health directly reflects upon fetal health, women make sure that they take the necessary steps to avoid having any pregnancy-related complications.

Pregnancy brings about a lot of physiological and hormonal changes in women including appetite, food habits, and oral health. Due to these changes, there is a high risk for the formation of dental caries. It is therefore important for pregnant women to maintain good oral hygiene and seek treatment if required. Women during pregnancy are quite reluctant to undergo any kind of dental procedures for the fear of local anesthetic drugs crossing the placenta and affecting the fetus. A frequently asked question asked by women who are supposed to undergo a dental procedure is – is dental anesthesia safe during pregnancy?

Risk of Dental Anesthesia During Pregnancy

• During the end of the second trimester and throughout the third trimester, the enlarged uterus tends to compress the abdominal aorta and the inferior vena cava (a large vein which drains impure blood into the right atrium of the heart) in the supine position (lying down on the back).
• This is called Aortocaval compression which causes a 14% reduction in the cardiac output and eventually reduced blood supply to the uterus. This condition affects the fetus negatively and is called supine hypertensive syndrome.
• Due to the risk of aortocaval compression, performing dental treatments during the third trimester needs to be re-considered as a pregnant woman during the third trimester cannot remain in a supine position for long durations.
• Toxic effects of dental anesthesia can be particularly seen on the central nervous system in the form of seizures and reduced consciousness.
• After an episode of seizure, catecholamine secretion increases which result in reduced blood flow to the placenta and eventually to the fetus.
• Protein binding capacity to local anesthetics is reduced in women having eclampsia or pre-eclampsia, which means that a large number of local anesthetic drugs can be transferred to the fetus through the placenta.
• Epinephrine used in the dental cartridge is a vasoconstrictor and can significantly reduce blood flow to the placenta by contracting blood vessels inside the uterus.
• If the general condition of the fetus is poor due to reduced placental perfusion and mother’s pregnancy-related medical conditions such as diabetes and hypertension, the quantity of local anesthesia not bound to proteins increases and gets trapped inside the fetus resulting in complications.

Due to the above reasons, a dose of dental anesthesia needs to be carefully planned and administered to high-risk pregnant women who are supposed to undergo treatment. These factors are potentially responsible for pregnant women as well as dentists being reluctant to even perform necessary dental treatments.

Is Dental Anesthesia Safe During Pregnancy?

A major concern for drug and anesthetic use during pregnancy is the significant risk of fetal malformations since most drugs can easily pass through the placenta. A dentist must, therefore, make a thorough assessment of the maternal and fetal condition prior to the administration of local anesthesia and medications to pregnant women.

Medications and anesthetic drugs should be used in pregnancy which offers benefit to the mother and least toxicity to the fetus. Use of dental anesthesia however during pregnancy prevents post-treatment long term use of anti-inflammatory pain killer medications and antibiotics.

During pregnancy, medications including local anesthetic drugs can be transferred to the fetus via the placenta. The severity of the effect of dental anesthesia upon the fetus depends upon the following factors

• Method of anesthesia administered
• Rate of metabolism
• The half-life of the anesthetic drug in mother
• Amount of drug delivered across the placenta
• The general health condition of the mother and fetus

Local anesthesia used for dental procedures such as tooth extraction or dental fillings is of two types – Ester or Amide. Ester types have a shorter duration of action as compared to amide type. Ester types are more likely to induce an allergic reaction which poses a threat to both mother and fetus.

Risk of fetal malformation due to use of medications is least during the second trimester. Dental anesthesia is, therefore, safer during the second trimester as compared to the first and third trimester. Dental anesthesia can also be used in low doses during the third trimester.

The following research studies have been done previously to claim that dental anesthesia does not affect pregnancy negatively

• A study conducted during 1959 and 1965 included 60000 pregnant women concluded that the administration of local anesthetics did not cause any fetal complications.
• A study conducted on 351 pregnant women who had to undergo dental procedures concluded that dental treatment did not increase the rate of negative pregnancy and fetal outcomes.

These studies prove that there is no clear evidence that use of dental anesthesia during pregnancy increases complications for the mother or the baby. Conversely, studies also report that poor oral health of women during pregnancy increases the risk of gestational diabetes, pre-eclampsia, and preterm birth. For this reason, maintaining oral health during pregnancy is an important aspect.

Lidocaine is the most widely used local anesthetic drug which does not have any negative documented effects on the pregnant woman and fetus. However, special care needs to be exercised in many cases. Toxic effects of dental anesthesia may be seen when the dose administered exceeds the maximum permissible dose. It is usually advised to pregnant women to undergo regular dental treatments (not emergency dental procedures) after the second trimester since medications and local anesthetic drugs tend to have a teratogenic effect on the fetus when used during the first trimester.

Pregnant women should avoid elective dental procedures during the first trimester and later half of the third trimester. Extensive dental reconstructive procedures should be preferably completely avoided throughout pregnancy. Additionally, pregnant women who have gestational illnesses such as diabetes and hypertension are at significantly high risk of developing major pregnancy-related complications in response to even the minutest dose of dental anesthesia administered. It is therefore important to carefully determine the dose of dental anesthesia for such women.