Paracetamol During Pregnancy May Affect Reproductive Development in Baby Girls, New Study Finds
A new Danish study has raised fresh questions about whether exposure to paracetamol during pregnancy could influence the reproductive development of baby girls.
Researchers found that girls exposed to the commonly used painkiller before birth had measurable differences in the size and development of their ovaries and wombs during infancy. Some exposed girls also appeared to have fewer ovarian follicles, the structures that contain immature eggs.
However, the researchers have stressed an important point: the findings do not prove that paracetamol causes fertility problems later in life.
The study, published in Human Reproduction Open, is observational. That means researchers identified an association between reported paracetamol exposure and certain developmental measurements, but they cannot establish that the medicine itself caused those differences.
What did the researchers find?
The study was conducted by researchers at Rigshospitalet in Copenhagen as part of the Copenhagen Analgesic Study, known as COPANA.
Researchers initially enrolled 685 pregnant women and subsequently examined 302 of their daughters during infancy. The girls were assessed at around three months of age, a period when reproductive hormones are temporarily active as part of what is sometimes called "mini-puberty".
The researchers collected information about paracetamol use from the mothers during pregnancy. They also analysed urine samples from many of the women to look for evidence of paracetamol exposure.
The researchers divided the girls according to when exposure to the medicine began during pregnancy.
Among girls whose mothers had used paracetamol during the earlier stages of pregnancy, before 17 weeks of gestation, ovarian volume was lower than in girls who had not been exposed.
The study estimated that ovarian volume was approximately 41 per cent lower after adjustment for other factors. Uterine volume was also lower, by approximately 13 per cent.
For girls exposed later in pregnancy, the researchers found an association with a lower number of ovarian follicles. The estimated difference was about 23 per cent compared with girls in the unexposed group.
These follicles are important because they contain immature eggs. A woman is born with a finite supply of ovarian follicles, although the relationship between measurements in infancy and fertility decades later is complex.
The study also identified differences in levels of reproductive hormones, including anti-Müllerian hormone, or AMH, which is commonly used as one marker of ovarian function.
Does this mean the girls could become infertile?
Not necessarily.
This is the most important qualification surrounding the research.
The researchers did not follow the girls into adulthood to determine whether they experienced difficulty becoming pregnant. Nor did the study demonstrate that the girls would experience earlier menopause or reduced fertility.
Instead, it measured biological characteristics during infancy and compared them with prenatal exposure to paracetamol.
The authors themselves say that the long-term significance of the findings remains uncertain. They recommend longer follow-up to determine whether the differences seen during infancy have consequences for reproductive health later in life.
That distinction matters. A smaller ovary or womb in infancy does not automatically translate into infertility as an adult.
Why are scientists paying attention?
The research is attracting attention because it adds human evidence to a broader scientific question.
Previous animal studies have reported reproductive effects following exposure to paracetamol during pregnancy. Those experiments have suggested that exposure can interfere with the development of ovarian follicles in female offspring.
The Danish researchers say their human findings are consistent with some of those experimental observations. However, animal research and human observational research have different limitations, and results from laboratory studies cannot automatically be applied to people.
Another notable feature of the Danish research is that the investigators looked at a second group of girls.
An independent cohort involving 1,210 girls was used to examine whether some of the findings could be observed beyond infancy. In this separate group, researchers reported associations between prenatal exposure and smaller reproductive organs at later stages of development, including adolescence.
However, the confirmatory cohort had differences in how exposure was recorded, and the researchers continue to emphasise that long-term clinical consequences have not been established.
What should pregnant women do?
The study does not provide a basis for pregnant women to panic or stop taking prescribed or recommended medicines without speaking to a healthcare professional.
Paracetamol, also known as acetaminophen, has long been widely used to treat pain and fever during pregnancy. Decisions about medication during pregnancy involve weighing potential risks against the risks of untreated illness, particularly significant pain or fever.
The new study is therefore best viewed as evidence that warrants further investigation rather than proof that paracetamol is unsafe during pregnancy.
Pregnant women who are concerned about taking paracetamol should discuss their individual circumstances with their doctor, midwife or pharmacist. They should also avoid exceeding the recommended dose and should check combination medicines carefully, as some products may already contain paracetamol.
More research is needed
The Danish researchers say larger studies with longer follow-up are needed before scientists can determine whether the differences they observed have any meaningful effect on reproductive health.
Future research will need to establish whether girls exposed to paracetamol before birth go on to experience differences in puberty, menstrual development, ovarian reserve, fertility or the timing of menopause.
It will also be important to account for why women took paracetamol in the first place. Pain, fever, infections and other health problems during pregnancy could themselves influence pregnancy outcomes, making it difficult to separate the effects of the underlying illness from those of the medicine.
This is one reason observational studies need to be interpreted carefully.
A finding that needs context
The new research is significant because it examines a question that has received comparatively limited attention in humans: whether exposure to a widely used medicine during fetal development could have consequences for the reproductive system many years later.
But the study does not show that girls exposed to paracetamol will have fertility problems.
What it does show is that researchers detected measurable differences in ovarian and uterine development among some exposed girls. Those differences deserve further investigation, particularly because reproductive development begins long before puberty and involves complex biological processes.
For now, the most accurate interpretation is that the study has identified a potential association, not a confirmed cause of infertility.
As the children in the research grow older, long-term follow-up should provide a clearer answer about whether the early differences have any lasting importance.
Until then, the findings should be considered an important research signal rather than a reason for alarm.
Sources
- Fischer MB et al., "Fetal exposure to paracetamol is associated with altered markers of ovarian development and reduced uterine volume in girls: the COPANA study," Human Reproduction Open, 8 September 2026.
- European Society of Human Reproduction and Embryology, "Paracetamol use during pregnancy is linked to changed reproductive development in daughters," 8 September 2026.
- Fischer MB et al., "Connecting prenatal exposure to paracetamol with postnatal reproductive development: a first of its kind study in reproductive toxicology," Human Reproduction Open, 2026.
Disclaimer
This article is provided for general information and educational purposes only. It is based on published research and does not constitute medical advice. The Danish study was observational and cannot establish that paracetamol causes reduced fertility or reproductive problems. Pregnant women should not change or stop medication solely because of this article. Anyone who is pregnant, planning a pregnancy, or concerned about pain or medication use should seek advice from a qualified healthcare professional.