If your baby’s teeth emerged earlier than everyone else’s, you have probably wondered why. Some parents credit great genes, while others think their little one is ahead of others their age. Scientists are now exploring whether the timing of teething may begin taking shape long before birth, inside the womb.
A new study from the United States has uncovered patterns that researchers say could reshape our understanding of early milestones and the factors influencing them, long before a baby is born.
Early teething and pregnancy hormones: What the study found
A study published in Frontiers in Oral Health followed 142 pregnant women from socioeconomically disadvantaged backgrounds. They tracked their hormone levels during the late second and third trimesters. Researchers then monitored each child’s teeth eruption at seven time points up to age two.
The findings revealed considerable variation, which is expected. Babies typically get their first teeth anywhere between six months and three years. But for the first time, researchers identified a clear biological link.
“A mother’s higher levels of stress-related hormones, particularly cortisol, during late pregnancy are associated with the earlier eruption of primary teeth in her infant,” explains Dr Ying Meng, an associate professor at the School of Nursing of the University of Rochester.
The data showed that infants of mothers with the highest cortisol levels had, on average, four more erupted teeth by six months than infants of mothers with the lowest levels.
How pregnancy hormones influence tooth eruption
Cortisol, the body’s main stress hormone, appears to play a role in how teeth mineralise and develop in the womb.
“High maternal cortisol during late pregnancy may alter fetal growth and mineral metabolism, including the regulation of levels of calcium and vitamin D, both essential for mineralisation of bone and teeth, explained Meng.”
The study also identified weaker but statistically significant links between other hormones (estradiol, progesterone, testosterone and triiodothyronine) and the number of teeth present at 12, 18 and 24 months. These hormones are already known to influence fetal development, birthweight and bone growth.
Importantly, diagnosed maternal anxiety or depression was not associated with hormone levels or tooth eruption timing, meaning the effect is biological, not behavioural.
Should parents worry about early teething?
Not necessarily. Early teething is typically harmless and paediatricians generally consider it part of normal variation.
However, the researchers note that earlier tooth eruption may reflect what they call “accelerated biological development”, sometimes linked to prenatal stress exposure.
For South African parents, many of whom experience pressures, financial challenges, limited maternity support, or work-related stress, the findings highlight why accessible prenatal care and support remain essential. Expectant mothers can also lower their stress levels by making time for a stress-reducing hobby.
Paediatricians recommend simply noting early teething during routine baby checks, especially if combined with other developmental concerns.
For now, parents can take comfort knowing that early teething is usually normal. Science is simply giving us a better understanding of the journey babies take long before they are born.
