Long term use of an over-the-counter pain reliever by pregnant women may adversely affect the development of their children, according to a new study by researchers in Norway.
Acetaminophen is used in all stages of pregnancy and is often recommended by doctors to treat fever and minor pain, but very few studies have investigated the possible long-term consequences for the unborn child.
The study from the Norwegian Institute of Public Health found that children exposed to acetaminophen for more than 28 days during pregnancy had substantially poorer motor skills, poorer communication skills and more behavioral problems compared to their unexposed siblings.
Acetaminophen is the generic name of a common active ingredient found in medicines to treat headaches, allergies, colds, coughs and to help people sleep. Excedrin, Tylenol and Nyquil are just a few of the brand names that use acetaminophen in their OTC medications. Acetaminophen is also combined with opioids to make more powerful prescription painkillers such as Vicodin.
Outside the United States, acetaminophen is known as paracetamol.
“The results strengthen our concern that long-term use of paracetamol during pregnancy may have an adverse effect on child development, but that occasional use for short periods is probably not harmful to the fetus,” said Hedvig Nordeng, a professor at the School of Pharmacy, University of Oslo and a researcher at the Division of Mental Health, Norwegian Institute of Public Health.
“Importantly, we cannot assume that there is a causal relationship between maternal use of paracetamol during pregnancy and adverse effects in children from an epidemiological study. Since this is the only study to show this, there is a need for further research to confirm or refute these results.”
The study used data from the Norwegian Mother and Child Cohort Study to investigate the effect of acetaminophen during pregnancy on motor skills, behavior and temperament at 3 years of age. Almost 3,000 brothers and sisters were included in the study.
The siblings exposed to prenatal acetaminophen for more than 28 days had poorer gross motor development, less confidence, poorer communication skills, more behavioral issues and higher activity levels.
Children exposed prenatally to short-term use of acetaminophen for less than 28 days also had poorer gross motor skills, but the effects were smaller than with long-term use. Ibuprofen exposure was not associated with neurodevelopmental outcomes.
“The findings support the advice of medical authorities; the first choice for pain is paracetamol, but one should be restrictive with all medicine use in pregnancy,” says Nordeng.
Acetaminophen has long been associated with liver injury and allergic reactions such as skin rash. In the U.S. over 50,000 emergency room visits each year are caused by acetaminophen, including 25,000 hospitalizations and 450 deaths.
The Food and Drug Administration has cautioned parents to be careful about the dose of acetaminophen for their children, but there are no specific warnings for pregnant women or nursing mothers.
One study found no risk of major birth defects for mothers who use acetaminophen during the first trimester.
The Norwegian study is collaboration between the University of Oslo, the Norwegian Institute of Public Health and the Hospital for Sick Children in Toronto, Canada. It was published in the International Journal of Epidemiology.