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Paracetamol During Pregnancy: Could A Painkiller Affect Baby’s Reproductive Development? What New Study Found
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Newsexplainers Paracetamol During Pregnancy: Could A Painkiller Affect Baby’s Reproductive Development? What New Study Found
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Among girls exposed to paracetamol before 17 weeks of pregnancy, researchers found smaller ovarian and uterine volumes compared with girls who were not exposed
Researchers found that prenatal exposure to paracetamol was associated with differences in markers of ovarian development in baby girls.
Paracetamol is one of the medicines many pregnant women are advised they can use for pain and fever. But a new Danish study has raised question on how a common medicine intake during pregnancy could affect a baby girl’s reproductive system.
Published on September 8 in Human Reproduction Open, the study is the first human study specifically designed to examine whether prenatal exposure to paracetamol is associated with markers of ovarian development. Researchers found differences in ovarian and uterine measurements among exposed girls, as well as differences in some markers of ovarian activity. The findings were also examined against a separate group of more than 1,200 girls followed into adolescence.
But the study does not show that paracetamol causes these changes, nor does it establish that girls exposed before birth will have fertility problems later in life.
What Did The New Study Find?
The study comes from the Copenhagen Analgesic Study (COPANA), a prospective observational study conducted at Copenhagen University Hospital-Rigshospitalet.
Researchers initially enrolled 685 healthy pregnant women. Their daughters were subsequently examined during infancy, when reproductive hormones and reproductive organs undergo a temporary period of activity known as mini-puberty. The analysis included 302 infant girls.
The researchers tracked mothers’ paracetamol use through regular reports during pregnancy and also measured paracetamol in urine samples. They then looked at whether the timing of exposure was associated with differences in the girls’ reproductive development.
Among girls exposed earlier in fetal life, before 17 weeks of pregnancy, researchers found smaller ovarian and uterine volumes compared with girls who were not exposed. Exposure later in fetal development was associated with fewer ovarian follicles.
The differences were measurable rather than evidence of a disease. Researchers also found differences in reproductive hormone markers, including lower anti-Müllerian hormone (AMH) in a subgroup exposed exclusively during early fetal life. AMH is one of the markers used to assess ovarian activity and the pool of developing follicles.
The study also found an inverse association between maternal urinary paracetamol concentrations and ovarian and uterine volume, as well as breast tissue diameter in the infants.
What Researchers Found In Older Girls?
The researchers also examined an independent group from the Copenhagen Mother-Child Cohort, which included 1,210 girls followed from fetal life through adolescence. This cohort was not originally created specifically to study paracetamol and reproductive development, so the exposure information was based on mothers’ reports of medication use during pregnancy.
That analysis provided some additional evidence in the same direction. Prenatal exposure was associated with smaller uterine volume around puberty and smaller ovarian volume during adolescence.
That makes the finding harder to dismiss as simply an observation confined to infancy. But it still does not answer the most important question for parents: what does this mean for reproductive health decades later?
The researchers say the long-term clinical significance of these differences remains unknown.
Does This Mean Paracetamol Can Cause Infertility?
No. The COPANA researchers observed an association between reported or measured exposure and certain markers of reproductive development; they did not randomly assign pregnant women to take paracetamol or not take it. That means other factors could potentially contribute to the differences seen.
The researchers did account for a number of maternal and pregnancy-related factors, and they say the associations remained after accounting for fever and other maternal factors. But, as with observational research, residual confounding cannot be completely ruled out.
There is also no evidence from this study that the girls will have difficulty becoming pregnant, experience earlier menopause or develop a reproductive disorder later in life. Those are questions that can only be answered by following children over much longer periods.
Why Is This Finding Important, Then?
The significance lies partly in the question the researchers are asking. Much of the debate around medicines during pregnancy focuses on immediate outcomes such as birth defects, pregnancy complications or childhood development. The COPANA study examines whether the exposure during fetal development be associated with changes in the reproductive system may only become relevant much later in life? That is a different way of thinking about medicine safety in pregnancy.
The ovaries develop before birth, and the number of ovarian follicles is established during fetal life. The researchers were therefore interested in whether an exposure during pregnancy might be associated with measurable changes in ovarian development.
Animal studies have previously reported effects of prenatal paracetamol exposure on ovarian follicle formation and reproductive outcomes. The new study provides human observational data in an area that had previously been less directly examined. But an association in infancy or adolescence is not the same as demonstrating an effect on fertility.
Should Pregnant Women Stop Taking Paracetamol?
The new study does not provide a reason for pregnant women to stop taking medically advised paracetamol on their own.
Current clinical guidance continues to regard paracetamol, or acetaminophen, as a first-line option for pain and fever during pregnancy when used appropriately. UK medicines guidance updated in 2026 says paracetamol can be used during pregnancy and recommends the lowest effective dose for the shortest necessary duration.
The Medicines and Healthcare products Regulatory Agency has also reiterated that paracetamol remains the recommended first-choice painkiller during pregnancy when taken as directed, while warning that untreated pain and fever can themselves pose risks.
The Society for Maternal-Fetal Medicine likewise continues to recommend acetaminophen as the first-line medicine for pain and fever during pregnancy. That does not mean pregnant women should self-medicate casually. Any medicine during pregnancy involves weighing its potential benefits and risks. Women who need repeated doses, have persistent pain or fever, or are taking several medicines should discuss their treatment with their doctor.
The immediate takeaway is not that a commonly used medicine has suddenly been declared unsafe. It is that a new area of research is raising questions that scientists do not yet have answers to. Researchers will need to establish whether these early differences persist, whether they affect puberty or reproductive function, and ultimately whether they have any meaningful impact on fertility or reproductive lifespan.
For now, the study adds a new question to the scientific debate around paracetamol in pregnancy, but it does not provide an answer that should prompt women to abandon an established treatment without medical advice.
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The COPANA study found that girls exposed to paracetamol before 17 weeks of pregnancy had smaller ovarian and uterine volumes in infancy compared to unexposed girls. Exposure later in fetal development was linked to fewer ovarian follicles, and differences were also noted in reproductive hormone markers like lower anti-Müllerian hormone (AMH). However, the study only observed associations and does not prove that paracetamol causes these changes or leads to future fertility problems.
Yes, the analysis of 1,210 girls from the Copenhagen Mother-Child Cohort provided additional evidence in the same direction. Prenatal exposure to paracetamol was associated with smaller uterine volume around puberty and smaller ovarian volume during adolescence. Despite these findings, researchers emphasize that the long-term clinical significance of these differences remains unknown, and it is still unclear what this means for reproductive health decades later.
No, the study does not provide a reason for pregnant women to stop taking medically advised paracetamol. Current clinical guidance, including UK medicines guidance updated in 2026, continues to recommend paracetamol as the first-choice painkiller for pain and fever during pregnancy when used at the lowest effective dose for the shortest duration. Untreated pain and fever can pose their own risks, so women should consult their doctors before changing their treatment.
Shilpy Bisht is a News Editor at News18, where she leads the English app operations. She writes on world affairs, health, AI, career, business, and issues affecting women and children. A former print …Read More
First Published:
September 11, 2026, 14:56 IST
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Published on September 8 in Human Reproduction Open, the study is the first human study specifically designed to examine whether prenatal exposure to paracetamol is associated with markers of ovarian development. Researchers found differences in ovarian and uterine measurements among exposed girls, as well as differences in some markers of ovarian activity. The findings were also examined against a separate group of more than 1,200 girls followed into adolescence.
But the study does not show that paracetamol causes these changes, nor does it establish that girls exposed before birth will have fertility problems later in life.
What Did The New Study Find?
The study comes from the Copenhagen Analgesic Study (COPANA), a prospective observational study conducted at Copenhagen University Hospital-Rigshospitalet.
Researchers initially enrolled 685 healthy pregnant women. Their daughters were subsequently examined during infancy, when reproductive hormones and reproductive organs undergo a temporary period of activity known as mini-puberty. The analysis included 302 infant girls.
The researchers tracked mothers’ paracetamol use through regular reports during pregnancy and also measured paracetamol in urine samples. They then looked at whether the timing of exposure was associated with differences in the girls’ reproductive development.
Among girls exposed earlier in fetal life, before 17 weeks of pregnancy, researchers found smaller ovarian and uterine volumes compared with girls who were not exposed. Exposure later in fetal development was associated with fewer ovarian follicles.
The differences were measurable rather than evidence of a disease. Researchers also found differences in reproductive hormone markers, including lower anti-Müllerian hormone (AMH) in a subgroup exposed exclusively during early fetal life. AMH is one of the markers used to assess ovarian activity and the pool of developing follicles.
The study also found an inverse association between maternal urinary paracetamol concentrations and ovarian and uterine volume, as well as breast tissue diameter in the infants.
What Researchers Found In Older Girls?
The researchers also examined an independent group from the Copenhagen Mother-Child Cohort, which included 1,210 girls followed from fetal life through adolescence. This cohort was not originally created specifically to study paracetamol and reproductive development, so the exposure information was based on mothers’ reports of medication use during pregnancy.
That analysis provided some additional evidence in the same direction. Prenatal exposure was associated with smaller uterine volume around puberty and smaller ovarian volume during adolescence.
That makes the finding harder to dismiss as simply an observation confined to infancy. But it still does not answer the most important question for parents: what does this mean for reproductive health decades later?
The researchers say the long-term clinical significance of these differences remains unknown.
Does This Mean Paracetamol Can Cause Infertility?
No. The COPANA researchers observed an association between reported or measured exposure and certain markers of reproductive development; they did not randomly assign pregnant women to take paracetamol or not take it. That means other factors could potentially contribute to the differences seen.
The researchers did account for a number of maternal and pregnancy-related factors, and they say the associations remained after accounting for fever and other maternal factors. But, as with observational research, residual confounding cannot be completely ruled out.
There is also no evidence from this study that the girls will have difficulty becoming pregnant, experience earlier menopause or develop a reproductive disorder later in life. Those are questions that can only be answered by following children over much longer periods.
Why Is This Finding Important, Then?
The significance lies partly in the question the researchers are asking. Much of the debate around medicines during pregnancy focuses on immediate outcomes such as birth defects, pregnancy complications or childhood development. The COPANA study examines whether the exposure during fetal development be associated with changes in the reproductive system may only become relevant much later in life? That is a different way of thinking about medicine safety in pregnancy.
The ovaries develop before birth, and the number of ovarian follicles is established during fetal life. The researchers were therefore interested in whether an exposure during pregnancy might be associated with measurable changes in ovarian development.
Animal studies have previously reported effects of prenatal paracetamol exposure on ovarian follicle formation and reproductive outcomes. The new study provides human observational data in an area that had previously been less directly examined. But an association in infancy or adolescence is not the same as demonstrating an effect on fertility.
Should Pregnant Women Stop Taking Paracetamol?
The new study does not provide a reason for pregnant women to stop taking medically advised paracetamol on their own.
Current clinical guidance continues to regard paracetamol, or acetaminophen, as a first-line option for pain and fever during pregnancy when used appropriately. UK medicines guidance updated in 2026 says paracetamol can be used during pregnancy and recommends the lowest effective dose for the shortest necessary duration.
The Medicines and Healthcare products Regulatory Agency has also reiterated that paracetamol remains the recommended first-choice painkiller during pregnancy when taken as directed, while warning that untreated pain and fever can themselves pose risks.
The Society for Maternal-Fetal Medicine likewise continues to recommend acetaminophen as the first-line medicine for pain and fever during pregnancy. That does not mean pregnant women should self-medicate casually. Any medicine during pregnancy involves weighing its potential benefits and risks. Women who need repeated doses, have persistent pain or fever, or are taking several medicines should discuss their treatment with their doctor.
The immediate takeaway is not that a commonly used medicine has suddenly been declared unsafe. It is that a new area of research is raising questions that scientists do not yet have answers to. Researchers will need to establish whether these early differences persist, whether they affect puberty or reproductive function, and ultimately whether they have any meaningful impact on fertility or reproductive lifespan.
For now, the study adds a new question to the scientific debate around paracetamol in pregnancy, but it does not provide an answer that should prompt women to abandon an established treatment without medical advice.
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