The Caution Principle

"Why do people take headache medications? They take it for hangovers, they take it for depression and it might be in response to trauma. The message is that women who are requiring that much painkiller in pregnancy ... need to have better monitoring of their pregnancy health."
Dr. Christine Loock, pediatrics professor, University of British Columbia

"It [acetaminophen] is generally one of the things that doctors feel comfortable in recommending. But, like many drugs used in pregnancy, we often don't have as much really solid information about that as one might expect there to be."
Dr. Jan Friedman University of British Columbia professor: drugs causing birth defects

A study undertaken by Boston University researchers in 2005 found that of over ten thousand expecting women 65% used Tylenol and other brands of acetaminophen, popular as an over-the-counter medication for pain and headache. That would make those medications the most commonly used such drug during the period of pregnancy. And a new Canadian co-authored study pinpoints acetaminophen's possible impact on fetuses.

The conclusion of the study authors was that pregnant women who use such medications for four weeks or longer are placing themselves at risk of delivering a child who may experience developmental problems. Using a large Norwegian health database the results were that offspring of heavy acetaminophen users were 70% more likely by age three to demonstrate relatively poor motor and communication skills. And to exhibit a range of troubling behaviour issues.

Toronto-based Dr. Gideon Koren, one of the authors of the study, and head of the Hospital for Sick Children's Motherisk program, cautions that  their conclusions do not prove a cause-and-effect relationship. An important issue has been raised requiring further study. The results were far from conclusive, he stressed, since expert assessment of the children was not carried out; rather there was reliance on mothers' impressions of their children's development and behaviour.

Some studies have discovered no link with the use of the painkillers and poor IQ, miscarriage and low birth weight. Still others find reason to believe there is a link with asthma and early birth, with the use of those popularly-used painkillers. Dr. Koren and his colleagues at University of Oslo used the Norwegian Mother and Child Cohort Study survey data on over 48,000 children and mothers from 1999 to 2008.

Of 2,919 sibling pairs, their mother used acetaminophen through pregnancy with some of their children, but not with others. Of those children about 5% (134) had been exposed to acetaminophen for 28 days or longer during pregnancy. The scientists drew the conclusion from the data they studied that pointed out these children were likelier to have poor motor and communication skills at age three.

Behaviours recognized as aggression ("externalizing behaviour"), and marked reticence (internalizing behaviour", were common within that cohort of acetaminophen-exposed children. On the other hand children who were exposed minimally while in utero experienced minimal problems. And those children whose pregnant mothers used ibuprofen, had no adverse reactions whatever.

Whether or not the children who experienced slower development and other instances deleterious to their well-being would eventually 'catch up' to normally developing children appeared not to have been addressed. Perhaps researchers are concerned with the dreadful history of unknown drug interaction with vulnerable developing fetuses, hearking back to the use of thalidomide and its horrible results.

It is well enough recognized that certain behaviours and ingestions should be avoided during pregnancy when women anticipate normal births and the development of healthy babies to result. Tobacco and alcohol are best avoided, along with recreational drugs and obviously, drugs like acetaminophen that may indeed have developmental risks for fetuses and infants.