Maternal and paternal postnatal depression and parental vocalisation behaviours in infancy: findings from UK-based birth cohort

Both maternal and paternal postnatal depression (PND) are associated with increased risk of less optimal offspring developmental outcomes. Early exposure to differences in maternal and paternal vocalisation behaviours that may be associated with maternal and paternal PND, may be important in this relationship. However, little research has captured vocalisation patterns at home without researchers present. This study sought to examine the associations between maternal and paternal PND and various aspects of parental vocalisation behaviours. Mothers (n=104) and fathers (n=34) of six-months old infants from the Avon Longitudinal Study of Parents and Children Generation-2 (ALSPAC-G2) provided video footage of mother- and father-infant interactions filmed at home in an ecologically valid way using head-worn video cameras (head cams) without the need for researchers to be present, with 25 mother-infant and father-infant interactions coded on multiple aspects of parental and infant vocalisation behaviours using the micro-behavioural observational coding system. Parental depression symptoms were measured using the Edinburgh Postnatal Depression Scale (EPDS) and analysed as a continuous score. Frequencies and duration of vocalisation behaviours were similar in mothers and fathers, however, there was an indication that fathers demonstrated higher frequency and duration of commands, exclamations and ironic/sarcastic tone and criticisms compared to mothers, while mothers engaged in more teaching compared to fathers. Linear regression models indicated that maternal and paternal PND were not associated with the majority of vocalisation behaviours, however, there were some specific patterns observed mostly related to the emotional tone of the vocalisations. Higher levels of maternal PND were associated with lower frequency of speech in a neutral tone, frequency and duration of use of humour, and increased duration of speech in a positive tone. Higher levels of paternal PND were associated with higher mean duration of speech, infant-directed speech, higher frequency and duration of laughing, and increased duration of speech using questions and encouragement. These findings extend existing research by investigating the associations between maternal and paternal PND and a wide range of vocalisation behaviours captured and coded using innovative methods and in a more ecologically valid way than previous studies. Many of the associations between parental PND and vocalisations did not support hypotheses suggested by existing literature, which may reflect the changing nature of contemporary parenting practices in the context of PND, improved ecological validity or methodological limitations of the study, including the explorative nature and multiple statistical comparisons. However, if replicated, the pattern of findings could suggest that depression in parents can be associated with more emotionally sensitive behaviours, particularly in fathers (such as higher duration of positive tone, encouragement and infant-directed speech), but also those potentially indicating lower parenting confidence (such as higher duration of questions and reduced use of neutral tone).