Negative effects of anesthesia in the first trimester are a valid concern. Being pregnant brings such joy and yet so much concern for your baby. By the time you learn that you are pregnant, your baby's spinal cord and heart will have already begun to form. Her major body systems have started to develop. Your baby's life depends upon your health and your avoidance of situations that may harm development.
Types of Anesthesia
Anesthesia is administered in two broad forms: local or general. Local anesthesia is often used in dentistry or for treating superficial wounds. Agents that block pain and your body's ability to detect it deaden feeling in an area. In turn, general anesthesia produces a state of unconsciousness that also prevents your body from feeling pain.
Potential Effects of Anesthesia
During pregnancy, the mother and her fetus share a physical bond through the umbilical cord. Blood is exchanged and waste leaves the fetus through the umbilical arteries. In effect, anything that can affect the mother's blood can likewise affect her baby.
Anesthesia acts on the brain and the central nervous system. During the first trimester, early development of these structures is occurring. The potential effects of anesthesia will depend upon the type administered and the overall health of the mother. Whether or not the anesthesia can cross the placenta, is another factor for assessing risk.
Negative Effects of Anesthesia in First Trimester
A study by doctors at George Mason University found that children born to mothers who had dental procedures with local anesthesia during their pregnancy had lower birth weights than those with no exposure. The study further suggested the possibility of neonatal behavioral changes in children exposed to anesthesia during the first trimester of development.
A 1994 study published in the American Journal of Public Health showed negative effects of anesthesia in the first trimester, finding links between central nervous system defects and hydrocephalus when mothers received anesthesia during this time frame. Hydrocephalus is a swelling of the brain that occurs because of a blockage or inflammation that interferes with the drainage of fluids within the brain. Children of mothers with some form of congenital defect were exposed to general anesthesia versus local during the first trimester of development. The study also found links between eye defects such as cataracts and anesthesia exposure.
Scientists often rely on animal research for information on the physical changes on 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 have to rely on observations after a baby is born.
While evidence suggests it can be harmful, other studies have found that anesthesia does not pose serious risks. As long as the anesthesia cannot cross the placenta, risks to the developing fetus are reduced. According to the American Pregnancy Association, local anesthesia is not a threat to your baby.
Scientists at Duke University Medical Center 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.
Clearly 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 risk must be specifically defined.
As a mother, you want to do what is best for your baby. While studies differ on the potential impact, perhaps the message to take away is that unless it is necessary, you may want to avoid surgery or dental procedures that require anesthesia. Another thing to bear in mind is that often these procedures require x-rays. Even if the anesthesia is not a significant risk, postponing these procedures minimizes your baby's exposure to radiation.