Relationships between infant crying, birth complications, and maternal variables.
The aim of the study is to identify factors influencing infants' crying behaviour (total crying duration, length of crying bouts, and frequency of crying). The searching for variables explaining inter-individual differences requires a sufficient stability of the cry parameters at least over short time intervals. Thus, a second aim is to assess the intra-individual stability of the crying behaviour in an age range from 3 to 12 months. Sixty-two mother-child dyads participated in the study. The results show substantial stabilities of the crying behaviour of infants between 3 and 12 months of age. This is related to the amount of crying as well as to the pattern of crying shown by the children over a 24 h interval. The typical cry pattern is characterized by peaks at 12.00 h and early in the evening, although there are large individual differences between the children with regard to cry durations at each hour of the day. Regarding the cry durations at 3 months of age, birth complications and the perceived emotional atmosphere in the mothers' family of origin are the major contributing factors.