Findings conclude that balance of hormones in the uterus are altered by taking paracetamol, also known as acetaminophen (APAP).
A new study has now revealed that women who take paracetamol during pregnancy risk lowering their child's IQ.
Not only that, the study finds that taking the drug is also associated with a higher risk of ADHD (attention deficit hyperactivity disorder) and autism.
Researchers from US universities, including Harvard, reviewed nine studies that looked at 150,000 mothers and babies in total.
Their findings conclude that balance of hormones in the uterus are altered by taking paracetamol, also known as acetaminophen (APAP).
Speaking about it, Post Doctoral Fellow Ann Z.Bauer said that exposure to APAP is so commonplace that the public health implications of even a modest elevation in adverse neurodevelopmental risk are substantial.
One study analysed found a three-point drop in IQ for five-year-old children whose mothers had taken paracetamol for pain relief without fever.
Other research shows youngsters exposed to the drug in the womb struggled with speech.
Notably, this is not the first time scientists have found a link between paracetamol use and delayed speech.
It turns out that expectant mothers who take acetaminophen more than six times during their early pregnancies are significantly more likely to have daughters with limited vocabularies, the study found.
Paracetamol is generally available without prescription and is the most commonly used medication in pregnancy.
Research has also shown the common painkiller can raise a child's risk of ADHD by up to 30 per cent, and up to a 20 per cent for autism, when taken by their mothers.
The study, led by Dr Ilan Matok, from the Hebrew University of Jerusalem, analysed 132,738 mother-child pairs over three-to-11 years.
Following it. Dr Matok said that their findings suggest an association between prolonged acetaminophen use and an increase in the risk of autism and ADHD.'
The researchers of these latest findings, published in the journal Hormones and Behavior, said: 'Longer duration of APAP use was associated with increased risk.
Pregnant women are generally excluded from scientific research and so the vast majority of medications have not been adequately studied and the risks to the baby are often poorly understood.