Stress at three-month immunization: Parents' and infants' salivary cortisol response in relation to the use of pacifier and oral glucose

The aims of the present study were to investigate (1) whether the salivary cortisol response could be dampened during a routine three-month immunization if the infant received sweet-tasting solution in combination with a pacifier and (2) stress experienced by parents during immunization of the infant. Ninety-eight infants were included into one of four intervention groups: 'glucose and pacifier', 'water and pacifier', 'glucose', or 'water'. Saliva was collected before and 30 min after the immunization. Infants' crying-time and parents' self-reported stress (VAS) were measured before and after immunization. Infants in the 'pacifier and glucose' group had a significantly smaller change in salivary cortisol than infants in the other groups (F3, 72 = 3.1, p < 0.05). In the 'glucose and pacifier' group the median salivary cortisol levels decreased 33% after the immunization. In the 'water and pacifier', 'glucose', and 'water' group median cortisol increased with 50%, 42%, and 8%, respectively. No significant differences in crying-time were observed between the intervention groups. If the infant cried before the immunization, the crying-time during the immunization was longer (p < 0.01) and cortisol increased more (p < 0.05). Median cortisol levels for parents decreased after the immunization (p < 0.01). Median VAS increased 50% (p < 0.0001) after immunization. First time parents rated higher stress on VAS before immunization (p < 0.01). Parents' change in cortisol and VAS were significantly related to infants' crying time. In conclusion, the combination of oral glucose and pacifier dampen infants' salivary cortisol in response to the three-month immunization.