604 The Relationship between Birth Order and Sleep Patterns in 6-Month-Olds

Abstract

Abstract Introduction The influence of birth order has been investigated in many areas of child development, but few studies have examined its relationship with infant sleep; those that have yield contradictory findings. Moreover, nocturnal parental practices may differ depending on the number of children, but these characteristics are rarely studied. This study aimed to compare nocturnal parental practices and sleep patterns of first-born to non-first-born 6-month-olds. Methods The mothers of fifty-two 6-month-olds completed a 14-day sleep diary to record their infant’s sleep. The following variables were averaged: total nocturnal sleep duration (in minutes), longest consecutive sleep duration (without interruption; in minutes) and number of nocturnal awakenings. Independent t-tests were used to compare each sleep variable between first-borns (n = 21) and non-first-borns (2nd, 3rd or 4th born, n = 31). Chi-square tests were used to compare parental sleep practices (breastfeeding frequency and infant sleep location) between first-borns and non-first-borns. Results First-borns had a longer consecutive nocturnal sleep duration (417.83 ± 142.42 vs. 310.08 ± 118.23; p < .01) and fewer nocturnal awakenings (1.69 ± 1.07 vs. 2.57 ± 1.09; p < .01) than non-first-borns. However, first-born and non-first-born infants did not differ in terms of total nocturnal sleep duration (p > .05). Breastfeeding frequency and sleep location differed as a function of birth order: 57.9% of first-born infants were exclusively breastfed, compared to 89.7% of non-firstborn infants (χ2 (1, N = 52) = 6.56; p < .05). Furthermore, 20.0% of first-borns slept in the parents’ room, compared to 56.7% of non-first-borns (χ2 (1, N = 50) = 6.62; p < .05). Conclusion First-born infants had longer periods of consecutive sleep and fewer nocturnal awakenings than non-first-borns; however, birth order was not associated with maternal reports of total nocturnal sleep duration. These results suggest that non-first-borns have more fragmented sleep. Moreover, sleep-related practices also differed between mothers of first-born and non-first-born infants. A study conducted in a larger sample and using objective sleep measures could clarify whether these different sleep patterns reflect specific nocturnal parental sleep-related practices, or if the presence of other children in the home play a role in infant sleep consolidation. Support (if any) SSHRC, FRQS