Negative Effects of Anesthesia in First Trimester

Julie Kirk
Doctor putting anesthesia in an open wound

Negative effects of anesthesia in the first trimester are a valid concern. By the time you learn that you are pregnant, your baby's spinal cord and heart will have already begun to form. The major body systems have started to develop. Your baby's life depends upon your health and your avoidance of situations that may harm development, so you may be concerned about anesthesia while pregnant.

Reasons Anesthesia May Be Needed

Although rare, unforeseen serious medical emergencies can occur when you are pregnant and surgery may be the only option. Approximately 2% of women will need to undergo surgery when pregnant. If the condition is truly urgent or life-threatening, surgery will be performed regardless of the trimester. However, if you are in your first trimester and the surgery is not urgent but still necessary, your doctor may want to wait until the second trimester which is typically the safest time to have surgery during pregnancy.

Necessary Surgery Examples

Surgery is typically avoided in the first trimester due to the potential risks of anesthesia or other medications that are given during the procedure that could possibly affect the developing fetus. A few examples of possible surgeries needed during pregnancy include:

  • Appendectomy
  • Gallbladder removal (Cholecystectomy)
  • Bowel (intestinal) obstruction

Types of Anesthesia

Anesthesia is typically administered in two broad forms: local or general.

Local Anesthesia

Local anesthesia is often used in dentistry or for treating superficial wounds. An anesthetic medication is used to numb a specific area or part of the body to block pain.

Woman dentist giving her patient an anesthesia injection

General Anesthesia

General anesthesia produces a state of unconsciousness or a sleep-like state that will prevent your body from feeling pain during a surgical procedure.

Potential Effects of Anesthesia

During the first trimester of pregnancy, your baby is growing and developing quickly. This is a critical time when your baby is most vulnerable and could potentially be at risk. Anything that the mother is exposed to can possibly affect her baby as well. In general, anesthesia acts on the brain and the central nervous system. During the first trimester, these structures are in their early development. The potential effects of anesthesia on the fetus will depend on what type is administered and the overall health of the mother. Whether or not the specific anesthesia used can cross the placenta is another factor for assessing risk.

Negative Effects of Anesthesia in First Trimester

There are studies that have indicated that anesthesia can cause negative effects. These include:

Behavioral Issues

According to one study it was found that exposure to anesthetics in utero can alter neuron migration in rats during brain development. This caused behavioral deficits in the rats. These results determined that caution should be used if anesthesia is administered during the neuronal migration period of brain development during pregnancy.

Physical Issues

According to another study on fetal exposure to anesthesia in the first trimester, it was found that surgery and anesthesia could be dangerous to the developing fetus. While there does not appear to be an increase in congenital anomalies there does appear to be an increase the risk of spontaneous abortion and lower birth weight. However, this may also be due to the surgery and medical condition rather than the actual exposure to anesthesia.

Doctor listening to babys heartbeat

Animal Research Is Important

Scientists often rely on animal research for information on the physical changes in fetuses. Sheep brains develop similarly to humans, giving researchers a good model. With human children, it is difficult to know the exact effects since doctors can only rely on observations after the baby is born.

Conflicting Studies

While evidence suggests it can be harmful, other studies have found that anesthesia does not pose serious risks.

Local Anesthesia Is Not a Threat

As long as the anesthesia does not cross the placenta, risks to the developing fetus are reduced. According to the American Pregnancy Association, local anesthesia (in particular) is not a threat to your baby.

Study Shows No Exposure Effects on Brain

A Duke University Medical Center study found that anesthesia may actually benefit the developing fetal brain by improving oxygenation. Further, evidence of physical effects of exposure on brain tissue was not found. Researchers identified isoflurane as one such agent. Like nitrous oxide, you inhale this anesthesia through a mask.

Additional Research Is Needed

As the conflicting studies indicate, more research is necessary to provide a pregnant woman with the best information for making choices during her pregnancy. Since anesthesia affects the brain and central nervous system, its risks must be specifically defined. While studies differ on the potential impact, it is recommended that unless the procedure or surgery is urgently needed, you may want to avoid surgery or even dental procedures that require anesthesia until after you deliver your baby.

Negative Effects of Anesthesia in First Trimester