Continued Paracetamol exposure during pregnancy linked to ADHD in offspring

By Dr. Ananya Mandal, MDOct 30 2017

A new study has found that long term or continued use of acetaminophen or paracetamol during pregnancy is linked to a doubled risk of attention-deficit hyperactivity disorder (ADHD) in children.

The study entitled, “Prenatal Exposure to Acetaminophen and Risk of ADHD” was published in the latest issue of the journal Pediatrics.

Acetaminophen or paracetamol is present in Tylenol and many other brands of over-the-counter drugs that are used for alleviating fever and pain. According the US Centers for Disease Control and Prevention (CDC), nearly 65 percent pregnant women in the United States are using Acetaminophen for pain and fever during pregnancy. The drug is generally deemed to be safe and effective for use.

However, this new study led by Eivind Ystrøm, a senior researcher at the Norwegian Institute of Public Health, questions the safety of this drug. Short term use of Acetaminophen for pain or fever during pregnancy is still the best option Ystrøm says. However, women who have been taking continuous acetaminophen for a longer period of time during their pregnancy need to be careful he added. In their study, longer duration of use of Acetaminophen was defined as 29 days.

This study was part of the Norwegian Mother and Child Cohort Study. The women in this study were included in the cohort after around 18 weeks of their pregnancy after undergoing a routine ultrasound examination. A total of 95,242 mothers and 75,217 fathers were included in the study. Between 1999 and 2009 a total 112,973 children were born. Of these 2,246 children were diagnosed with ADHD. A look at the medications the mothers were having showed that around 47 percent of women used acetaminophen during their pregnancy. Of these 27 percent used the OTC drug during one trimester, 16 percent used acetaminophen over two trimesters and less than 4 percent went on to use the drug in all the three trimesters of their pregnancy. Each trimester of pregnancy spans 3 months and there are three trimesters in a pregnancy.

Ystrøm explained that women who used acetaminophen for more than 29 days during their pregnancy had a 220 percent increased risk of ADHD in the child. The team, he went on to add, has already considered other risk factors for ADHD such as presence of ADHD in the family or other medical conditions.

These factors notwithstanding, paracetamol played a role in increasing the risk of ADHD in the children he said. When the use of acetaminophen was for less than seven days during pregnancy, the risk of ADHD was reduced. Ystrøm said that the study also found that if the fathers had used acetaminophen 29 or more days before conception, the risk of ADHD rose by twice.

This connection was poorly understood Ystrøm said. It could be that fathers with ADHD required to have more ADHD and were passing on their ADHD related genes to the babies. Or the other possible explanation could be the fact that long term use of acetaminophen could change the sperms to raise the risk of ADHD among the babies born out of those sperms.

The team believes longer term and more extensive studies are necessary to prove the connection between maternal and paternal acetaminophen consumption and ADHD in children. Several experts have added in their statements that this is too early to accept the results and stop use of acetaminophen among pregnant women when it is recommended and needed.

ADHD covers a wide range of behavioral symptoms which may include hyperactivity, lack of attention or concentration and tendency towards impulsive behavior.

Diagnosis of ADHD is usually made in children between ages 3 and 7 years. Since many of the symptoms of ADHD are present to a mild degree in many children, diagnosis using set criteria is important. ADHD may also manifest in adulthood.

There are classically three different types of ADHD. This classification is based on the strongest symptom showed by the child.

1. Predominantly Inattentive – This includes major symptoms like lack of attention, purposefulness to complete a given task, follow instructions and conversation and pay attention to smaller details. Distraction is common in these persons.
2. Predominantly Hyperactive – Persons with this type of ADHD often fidget and talk more than necessary. They find it difficult to sit still for work, meals or school. In toddlers, this may manifest as constant running, jumping and physical movements. This condition also manifests as impulsivity. The person may speak out of turn or grab things from others. This impulsivity also makes the individuals prone to accidents and injuries.
3. Combination of both types – These persons show a mixture of symptoms of both types.