Hair collections Hair samples are drawn by the midwife around 24 weeks of gestational age and three days after delivery. Long periods of stress are associated with increased hair cortisol concentrations (Stalder & Kirschbaum, 2012). Confounding variables are low maternal education, season of delivery, smoking during pregnancy and obesity (Braig, et al., 2015).Titanium scissors are cleaned with denaturated ethanol and the midwife wears disposable gloves in order to limit contamination. A lock of hair with a thickness of a match (2 mm) and a length of 4 cm will be taken and put in an envelope. Analysis will be performed at the University of Southern Denmark.