The use of over-the-counter (OTC) painkillers during pregnancy may be associated with an increased risk of health issues in babies, a study — described by its authors as “one of the largest … of its kind” — has suggested.
However, an expert warned that it is “impossible” to confirm whether the health issues were directly caused by OTC painkiller use as the study was unable to say why medicines were taken or whether other medicines were also taken that may have affected the pregnancy.
The researchers looked at data from the Aberdeen Maternity and Neonatal Databank from 1985 to 2015, covering 151,141 pregnancies, and analysed medical notes for use of paracetamol, aspirin, diclofenac, naproxen and ibuprofen.
The data, presented in a poster at the 2021 annual meeting of the European Society of Human Reproduction and Embryology, showed that nearly a third (29%) of women had taken at least one of the medicines during pregnancy, with the figure increasing to 60% over the final seven years of the study period.
There was an “association between increased health risks for pregnancies, where mothers were exposed to at least one of the five analgesics”, the study said, with the baby around 1.5 times more likely to experience health issues. These included neural tube defects, neonatal death and premature delivery before 37 weeks.
However, the study found that there was no significant association between paracetamol use alone and high birth weight, neural tube defects and hypospadias.
The authors also reported that diclofenac consumption was associated with significantly decreased odds of stillbirth.
Aikaterini Zafeiri, a PhD researcher at the University of Aberdeen’s Institute of Medical Sciences and leader of the study, said that “the ease of access to non-prescription painkillers, in combination with availability of correct or mis-information through the internet, raises safety concerns”.
Responding to the findings, Jane Bass, senior pharmacist in women’s services at Guy’s and St Thomas’ NHS Foundation Trust, warned it was “impossible to say whether the risks are caused by the painkillers as the study was unable to say why the women took these medicines or whether they were taking other medicines at the same time, which may have affected the pregnancy”.
However, it was “reassuring that any increase in adverse outcomes in women who had taken OTC painkillers in early pregnancy is low and reflects those effects seen in some other similar studies”, she said.
Bass noted that diclofenac tablets are no longer available OTC in the UK, “although diclofenac gel can still be purchased”.
“Women should speak to a healthcare professional if they wish to use it or the similar drugs ibuprofen, naproxen or aspirin in pregnancy.
“Diclofenac, ibuprofen, naproxen and aspirin (painkiller dose, not low dose for prevention of pre-eclampsia) are not recommended after 30 weeks of pregnancy unless the baby is being monitored,” she continued.
Bass added that websites such as Bumps (‘Best Use of Medicines in Pregnancy’), and NHS sites, “give clear guidance on the use of painkillers in pregnancy but many women are unaware of this and may get information from less reliable online sources”.
She also noted that the Medicines and Healthcare products Regulatory Agency has set up a Safer Medicines in Pregnancy and Breastfeeding consortium “to improve the health information available to women thinking about becoming pregnant, who are pregnant, or are breastfeeding”.
The findings show an increasing trend towards self-medication, which is “partly a reflection of health policy as availability of simple painkillers on prescription has been progressively restricted in the UK”, Bass said.
In March 2018, NHS England introduced restrictions on OTC prescribing for a range of minor, short-term health conditions to cut costs.