Excessive infant crying New insights in the role of parental factors and long-term stress through hair cortisol analysis

Excessive infant crying is one of the most distressing challenges for new parents and a common reason to visit a paediatrician. In the majority (95%) of excessively crying infants, no underlying organic disorder can be found. Therefore the focus of treatment should be on supporting the parents and helping them through this challenging period, and information on parental feelings is essential. This thesis shows that that, a maternal history of psychiatric disease, actual maternal depressive symptoms and postpartum bonding are important parental factors to consider when dealing with infant gastro intestinal symptoms. Infants of mothers with a history of psychiatric disease had more gastro-oesophageal reflux symptoms compared to controls, maternal depressive symptoms were associated with infant constipation, and bonding problems were associated with excessive infant crying. Second, both fathers and mothers with an excessively crying infant experience more feelings of stress, depression, anxiety and bonding problems compared to control parents, although father’s feelings of stress and bonding problems are more strongly influenced by maternal feelings of stress and bonding problems than by excessive infant crying. Thirdly, paediatric reference intervals of hair cortisol with liquid chromatography-tandem-mass spectrometry were determined and lower hair growth rates were found to be one of the explanations of the remarkably high hair cortisol concentrations in infancy. Finally, insight in long-term stress was gained by hair cortisol measurements in parents of excessively crying infants and mothers with a severe psychiatric disease and were shown to be significantly different compared to controls, while hair cortisol concentrations in their infants did not differ from the control group.