The Negative Effects of Anesthesia in the First Trimester

The Negative Effects of Anesthesia in the First Trimester
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Fetal Development

To put the risks of anesthesia in perspective, it is helpful to understand what is occurring during the first three months of your baby’s existence. During the first month, basic structural changes occur include development of the vertebral column, heart, and central nervous system.

By the third month, bone formation is underway. Your baby’s limbs are formed and her eyes and ears have begun developing. Negative impacts at this time could affect the baby’s survival and normal development.

Anesthesia Types

The risk of negative effects of anesthesia in the first trimester depend in part upon the type of anesthesia used. There are two general types, local and general. Your dentist may administer local anesthesia for a filling. You receive a general anesthesia for more invasive surgical procedures such as an appendectomy.

Anesthesia Risks

While you may certainly not plan on it, about 1 to 2 percent of women have non-birth-related surgery during their pregnancy. Laparoscopy is most commonly performed during the first trimester. This surgery examines the abdominal cavity for conditions of the female reproductive organs, biopsies, and other minor surgeries.

Concerns exist whether anesthesia will increase the risk of birth defects. A 2007 study published in Acta Anaesthesiologica Belgica found no increased risk of birth defects in pregnant women undergoing anesthesia. Yet, the same study did find an increased incidence of miscarriage and lower birth weight in infants.

The greatest risks during the first trimester are associated with general anesthesia. A 1994 study in the American Journal of Public Health found a higher incidence of hydrocephalus or water on the brain in children born to women who received general anesthesia during the first trimester.

Additional Risk Factors

Your own state of health plays a role in the risk of negative effects of anesthesia in the first trimester. An obese, pregnant woman has a higher risk of complications from surgery as well as her unborn child. Being overweight and in a stressful situation like surgery places enormous stress on the cardiovascular system. In addition, if you are overweight, you will likely stay in the hospital longer.

These risk factors translate into a higher potential for negative effects during the first trimester. Considering that the foundation of the cardiovascular, nervous, and skeletal systems is occurring, the impacts can be profound. Perhaps the wisest course of action is to err on the side of caution.

If surgery or dental work can be postponed, do so for your own peace of mind. While medical science continues to advance, the risk to your baby is far too much of a gamble.

Photo by Marek Bernat, stock.xchng


S. Allaert et al. First trimester anesthesia exposure and fetal outcome. A review. Acta Anaesthesiologica Belgica, 2007; 58(2):119-123.

K. Kuczkowski. The safety of anaesthetics in pregnant women. Expert Opinion on Drug Safety, March 2006; 5(2):251-264.

Science Daily: More Weight Equals Longer Hospital Stays

G C Sylvester et al. First-trimester anesthesia exposure and the risk of central nervous system defects: a population-based case-control study. American Journal of Public Health, November 1994; 84(11): 1757–1760.