A new study has uncovered an unexpected connection between a mother’s stress during pregnancy and how quickly her baby’s teeth appear.
Researchers from the University of Rochester, New York State, found that infants born to mothers with higher levels of the stress hormone cortisol tended to develop their first teeth earlier—sometimes, months ahead of peers.
Published in Frontiers in Oral Health, the research suggested that maternal stress can subtly accelerate biological aging in babies.
“A mother’s higher levels of stress-related hormones, particularly of cortisol, during late pregnancy are associated with the earlier eruption of primary teeth in her infant,” said lead author Dr. Ying Meng, an associate professor at the University of Rochester’s School of Nursing.
The team followed 142 women from disadvantaged backgrounds in the U.S., collecting saliva samples during the later stages of pregnancy to measure concentrations of cortisol and other hormones.
Their children’s teeth were then assessed by dentists at multiple intervals up to 24 months after birth.
By six months, babies of mothers with the highest cortisol levels had, on average, four more erupted teeth than those of mothers with the lowest levels.
The researchers believe cortisol may affect fetal growth and mineral metabolism—key processes that shape bone and tooth formation.
While the study also found minor links between other hormones such as estradiol, progesterone and testosterone and faster teething, cortisol emerged as the clearest factor.
The finding adds to a growing body of evidence suggesting that prenatal stress can alter a child’s developmental timeline in measurable ways.
“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 mineralization of bone and teeth,” Meng said. “Cortisol is also known to influence the activity of so-called osteoblast and osteoclast cells, responsible for building up, shaping, and remodeling bone.”
Normally, babies begin teething around 6 months of age, completing their full set of 20 primary teeth by age 3. But the researchers note that there is significant variation due to genetics, nutrition, and now, it seems, prenatal stress.
Meng said future studies will probe which biological pathways are most affected and whether early tooth eruption could be a sign of broader developmental acceleration.
“We still have key questions that need answering,” she added. “For example, which maternal hormones or downstream developmental pathways drive the change in the timing of tooth eruption … and what such speeding up says about a child’s general health.”
