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Go-to pregnancy pain-relieving drug delays babies’ speech

  • If women take acetaminophen more than six times in their early pregnancies
  • It is unclear how the drug delays language and why boys are unaffected
  • Previous research links acetaminophen to reduced IQ and communication
  • Acetaminophen is the active ingredient in many over-the-counter painkillers
  • Around 65% of pregnant women in the US take the drug when expecting 

The go-to pain-relieving drug in pregnancy delays babies’ speech by up to six times, new research reveals.

Expectant mothers who take acetaminophen more than six times during their early pregnancies are significantly more likely to have daughters with limited vocabularies, a US study found.

Although it is unclear how the drug causes delayed language development or why baby boys are unaffected, acetaminophen has previously been linked to communication problems and reduced IQ among children whose mothers took the medication when expecting.

Acetaminophen, also known as paracetamol, is the active ingredient in hundreds of over-the-counter medications, including Tylenol, and is the first-line painkiller for pregnant women to relieve fever and discomfort.

Around 65 percent of pregnant women in the US take the drug when expecting, according to the US Centers for Disease Control and Prevention.

The go-to pain-relieving drug in pregnancy delays babies’ speech by up to six times (stock)


Women exposed to air pollution before getting pregnant are nearly 20 percent more likely to have babies with birth defects, research revealed earlier this month.

Living within 5km of a highly-polluted area one month before conceiving makes women more likely to give birth to babies with defects such as cleft palates or lips, a US study found.

For every 0.01mg/m3 increase in fine air particles, birth defects rise by 19 percent, the research adds.

Fine air particles, which weigh less than 0.0025mg, are given out in vehicle exhaust fumes and, when breathed in, become deposited in the lungs where they enter the circulation.

Previous research suggests this causes birth defects as a result of women suffering inflammation and ‘internal stress’.

Birth defects affect three percent of all babies born in the US.

How the research was carried out 

Researchers from Mount Sinai hospital in New York analyzed 754 women who were between eight and 13 weeks into their pregnancies. 

The study’s participants were asked how many acetaminophen tablets they took between conception and the trial’s initiation.

Their urine was tested for it’s acetaminophen concentration.

Language delay, defined as using less than 50 words, was investigated by a nurse’s assessment and a questionnaire completed by the children’s parents when the youngsters were 30 months old.

‘Pregnant women should limit their use of this analgesic’ 

Results also reveal a high acetaminophen urine concentration in pregnant women is linked to delayed speech in infants.

Study author Dr Shanna Swan said: ‘Given the prevalence of prenatal acetaminophen use and the importance of language development, our findings, if replicated, suggest that pregnant women should limit their use of this analgesic during pregnancy.

‘It’s important for us to look at language development because it has shown to be predictive of other neurodevelopmental problems in children.’  

The findings were published in the journal European Psychiatry.