Danish study found foetuses with smaller wombs and ovaries, but researchers warn against drawing conclusions
Taking paracetamol in pregnancy may damage the future fertility of daughters, new research suggests.
Expectant mothers who used paracetamol gave birth to girls with ovaries that were 40 per cent smaller on average, according to the study.
They also had 13 per cent smaller wombs and 23 per cent fewer ovarian follicles, the structures within ovaries that produce eggs.
Girls are born with all the follicles they will ever have and animal studies have shown that impaired formation of ovarian follicles can lead to reduced fertility and earlier reproductive ageing.
Baby girls exposed to paracetamol in early foetal life also had lower levels of anti-müllerian hormone, which is a marker of ovarian egg reserve.
Dr Margit Bistrup Fischer, of Rigshospitalet, Copenhagen, Denmark, who led the study, said: “Whether the differences observed in our study have implications for fertility and age at menopause in humans remains unknown and will require long-term follow-up of the girls in our cohort.
“Women who have used paracetamol during pregnancy should not be alarmed by our findings. Our study examined associations at the population level and cannot predict outcomes for any individual woman or child.
“Many women who used paracetamol during pregnancy had daughters whose ovarian measurements were similar to those of daughters born to women who did not use paracetamol.”
Paracetamol is currently recommended as first-choice treatment for pain and fever for expectant mothers, although the NHS advises using the lowest effective dose for the shortest possible time.
It is considered that untreated pain and fever may cause greater risks to an unborn baby than any risks from paracetamol and is safer than ibuprofen or aspirin, which can harm a developing foetus’s heart or kidneys.
Trump’s shaky claims
But the drug has proved controversial in recent months, with the Trump administration claiming there are links to autism and ADHD.
Meta-analyses have found no link.
In the new research, researchers enrolled 685 Danish women during the first trimester of pregnancy and examined 302 baby daughters at three months old.
They monitored paracetamol levels using urine samples.
The researchers also looked at a separate group of 1,210 girls from the Copenhagen Mother-Child Cohort, who were followed from infancy to adolescence and whose mothers, during the third trimester, had reported any paracetamol use during pregnancy.
The mothers in the study took relatively low levels of paracetamol – mostly for headaches or musculoskeletal pain, rather than severe illness – and none exceeded the recommended daily maximum dose of 4,000mg.
Researchers have suggested that encouraging women to use non-pharmacological approaches such as rest, hydration, physiotherapy, exercise, and heat treatment may be a safer alternative.
Prof Christian De Geyter, who leads the department of reproductive medicine and gynaecological endocrinology at the University Hospital of Basel, Switzerland, said the findings were important.
“Recommendations on the use of paracetamol during pregnancy must now be revised,” he said.
However, British scientists have urged caution.
‘Impossible to make any causal claims’
Dr Gavin Stewart, statistical methods editor at the Campbell Collaboration, and a senior lecturer in evidence synthesis at Newcastle University, said: “This study requires extremely cautious interpretation.
“The study design means it’s impossible to make any causal claims. The small sample size and large numbers of outcomes make false positive findings very difficult to distinguish from any potential true effect. We cannot conclude from this study that paracetamol is causing these effects.”
Prof Franziska Denk, professor in neuroscience at King’s College London, added: “Right now, I think it is too early to recommend a change in behaviour – as correctly indicated by the authors in the press release.
“Pregnant women should not be worried.”
The research was published in Human Reproduction Open. (Telegraph)