Tylenol in Pregnancy and Adverse Childhood Neurodevelopment
Adapted from Acetaminophen Use During Pregnancy and Behavioral Problems in Childhood published in JAMA Pediatrics.
Tylenol may no longer be the “safe” drug for pregnant women.
Acetaminophen (the main ingredient in Tylenol) is used by a large proportion of pregnant women. A new study from England suggests that acetaminophen use in the second and third trimesters is associated with an increased likelihood of abnormal fetal neurodevelopment resulting in the subsequent occurrence of ADHD in the offspring.
ADHD (Attention Deficit-Hyperactivity Disorder) is a brain disorder marked by an ongoing pattern of inattention, hyperactivity, and impulsivity that interferes with functioning and development. Symptoms of ADHD are typically recognizable around age five.
This study was not the first to find an association. A study from the Danish National Birth Cohort found a similar risk, as did one looking at mother-child pairs in New Zealand. A separate study looking at sibling pairs and acetaminophen use during pregnancy found adverse developmental outcomes at age three years.
The current study examined associations between offspring behavioral problems and acetaminophen use:
- During pregnancy
- By the male partner
The researchers tried to isolate other potential prenatal causes of the ADHD, including smoking, alcohol use, socioeconomics, and genetics. Accounting for these possibilities, they still found acetaminophen use to have an association with higher levels of ADHD.
The researchers looked at data on nearly 8,000 women who were taking part in the Avon Longitudinal Study of Parents and Children, an ongoing study in the U.K., aimed at finding both environmental and genetic factors that affect people’s health and development.
The women and their partners filled out questionnaires that included questions about acetaminophen use at 18 and 32 weeks of pregnancy, and again when their children were five years old.
When the children turned seven, the women filled out another questionnaire, this time regarding any behavioral problems the children had.
When women took Tylenol at 18 weeks of pregnancy, such use was linked to between 31% and 42% increase in the risk of having a child with ADHD.
When women took the medication at 32 weeks of pregnancy, such use was associated with between 29% and 46% increase in the risk of ADHD.
No association was found between postnatal Tylenol use and ADHD.
Surprisingly, a subsequent observation from the study data published in the same Journal in April 2017, showed an association between male partner's Tylenol use and the prevalence of ADHD in the offspring.
It is important to remember that these connections are ones of association and not causation: researchers do not know whether taking acetaminophen caused the ADHD.
The mechanism how acetaminophen may cause behavioral problems is not well-known. The researchers believe, however, when a pregnant woman takes acetaminophen, the medication can cross the placenta, enter the fetus, and impact the brain development.
The male partner's Tylenol use association suggests possible acetaminophen influence on sperm development.
This leaves pregnant women with yet another risk factor to consider, along with alcohol, coffee, and other pain relievers.
As with any medication used by pregnant mothers, Tylenol should be used only when necessary.