Maternal stress during pregnancy accelerates the eruption of baby teeth

Such a conclusion was made by scientists from the USA, having analysed the relationship between the hormones of pregnant women and the timing of the appearance of the first teeth in their children. This is stated in a paper published in the journal Frontiers in Oral Health, reports Medicalxpress.

Normally, a child forms 20 milk teeth - 10 in each jaw. Their rudiments begin to develop in the womb, around the sixth week of pregnancy, and eruption usually occurs between six months and three years of age. However, the timing varies greatly and depends on the genetics, region of residence, health and nutritional status of the child.

Now researchers have shown that another factor can influence this process - the mother's stress levels at the end of pregnancy.

How the study was conducted

The team, led by Ying Meng, an assistant professor at the University of Rochester School of Nursing, followed 142 pregnant women from socioeconomically disadvantaged backgrounds in the US. The women were enrolled in the study between 2017 and 2022 through the University of Rochester Medical Centre.

In the late second and third trimesters, each participant gave saliva samples that measured concentrations of six hormones: cortisol, estradiol, progesterone, testosterone, triiodothyronine and thyroxine.

All babies were born prematurely. After birth, mothers along with their infants came to the clinic for check-ups at 1, 2, 4, 6, 6, 12, 18 and 24 months of age. Dentists recorded which baby teeth had already erupted.

By six months, 15 per cent of the children had one to six teeth; by 12 months, 97.5 per cent had one to 12 teeth. By the age of 18 months, all children had three to 20 teeth erupted, and by the age of two, a quarter (25 per cent) of children had all 20 milk teeth.

A small proportion of children (2.7 per cent) had a sharp "jump" in tooth eruption between 12 and 18 months of age, while the rest had a more gradual but uneven process - the early number of teeth did not predict their number later in life.

During pregnancy, 36.6 per cent of women had a diagnosis of depression or anxiety disorder, but such a diagnosis was not associated with hormone levels or the number of baby teeth erupted. The hormone profiles themselves, however, varied greatly between women, with some having consistently higher levels of almost all hormones and others having lower levels.

Cortisol and early teeth

A key finding concerns the stress hormone cortisol. Women with higher levels of cortisol in saliva at the end of pregnancy were more likely to have babies who had more teeth erupting by six months of age.

Babies of mothers with the highest levels of cortisol had an average of four more teeth by six months of age than children of women with the lowest levels of the hormone.

According to Meng, elevated cortisol in late pregnancy can alter fetal growth and mineral metabolism, including the regulation of calcium and vitamin D, which are critical for bone and tooth mineralisation. Cortisol also affects the activity of osteoblasts and osteoclasts, cells that form and remodel bone tissue.

The authors suggest that premature teething may be an early marker of accelerated biological aging in children and a signal of impaired oral development and general health associated with socioeconomic disadvantage and prenatal stress.

The role of other hormones

Researchers have also found weaker but statistically significant links between levels of other maternal hormones and the number of teeth a child has:

• increased estradiol and testosterone in the mother - with more teeth at 12 months;

• increased progesterone and testosterone - with the number of teeth at 24 months;

• elevated triiodothyronine - with more teeth at 18 and 24 months.

Estradiol, progesterone and testosterone are known to be important regulators of intrauterine development and birth weight, which may explain their effects on the rate of teething.

The researchers emphasise that many questions remain: which hormones and downstream signalling pathways are responsible for the shift in the timing of teething, how the acceleration of this process is related to the biological age and development of the child, and what this says about the child's overall health.