Although the first trimester of pregnancy is sacred, there will be patients who will encounter problems at that time. During the first trimester, the brain and the central nervous system develops from 6 to 10 weeks, a time period commonly known as organogenesis. Therefore, to minimize the risk of developing birth defects, medications and invasive procedures are usually postponed until the arrival of the second trimester.

A recent article in the October 2010 issue of Ob-Gyn News reported some disturbing findings: dental fillings in the first trimester were linked to the development of a cleft palate. A cleft palate is a birth defect that has a slit in the roof of the mouth because it failed to close during the 1st trimester. The article by Susan London described a study in Norway where pregnant women had dental filings in the 1st trimester and their babies subsequently developed cleft palates. Ideally, dental problems should be addressed prior to becoming pregnant however that is not always an option. Dental problems can occur during pregnancy because of the increased calcium requirements of the fetus as well as hormonal changes of the pregnancy.

The Norway medical study identified 573 infants that have facial clefts. It was thought that the fetal exposure to mercury from maternal fillings during a critical period in the development of its face may increase the risk of deformities. Amalgam fillings continuously give off small amounts of vaporized mercury that cross the placenta and accumulate in the fetus. Silver dental fillings contain 52% mercury. About 27 women had fillings placed in the first month of their pregnancy and quadrupled their risk of having a baby with cleft palate. Women who had fillings placed in multiple months of their pregnancy fared even worse. London suggests that further studies needs to be done, especially since the American Dental Association declined to comment regarding this matter.

Given the results of the Norway study, pregnant women should postpone dental work until the second trimester if at all possible and of course, discuss the matter with your obstetrician or midwife.

Do you know how to anticipate and manage the unexpected events that could occur during your pregnancy? You will if you purchase The Smart Mother’s Guide to a Better Pregnancy available on or wherever books are sold.