Background: The process of childbirth and its complications have been related to the newborn's condition and to development at later ages. In this study, we examine how mode of delivery and delivery complications are related to the behavior and cortisol reactivity of infants during the first 2 months.
Methods: Delivery factors (i.e. mode, duration, fetal heart function, and 5-min Apgar score) were determined in 116 healthy, term, firstborn infants. The infants' behavioral and cortisol reactivity to stressors were assessed during a physical examination at 11 days and an inoculation at 2 months. Daily behavior at 6 weeks was followed by means of a four-day parental diary.
Results: Indicators of a more stressful delivery were linked to more crying/fussing in the infant and to more difficulties in regulating the infants' behavior (i.e., more unsoothability and longer crying bouts). Specific delivery complications rather than mode of delivery were linked to infants' behavior. No significant associations however, were found between childbirth and the infants' cortisol reactivity to a physical examination and an inoculation.
Conclusions: Childbirth complications, even when mild, can apparently affect early infant behavior. These effects extend over different types of situations, and last at least until the age of 2 months, and should be taken into account in studies on infant behavior. Earlier findings of relations between childbirth complications and infant cortisol reactivity could not be replicated in this study, possibly due to the confounding effect of parity, and to the important intra-individual variability present in the infants' cortisol.