Introduction: This study aimed to examine factors associated with the attitudes of parents of 6-month-old infants, with respect to maintaining a daily life rhythm for their child.

Methods: Cross-tabulated data from nationwide cross-sectional surveys (the Longitudinal Survey of Newborns in the 21st Century), conducted in 2001 and 2010 by the Ministry of Health, Labour and Welfare of Japan, were used for analysis using a logistic regression model.

Results: We analyzed data of 47,010 infants from 2001 (response rate 87.7%) and 38,554 infants (response rate 88.1%) from 2010. The percentage of parents with positive attitudes towards maintaining a daily life rhythm for their baby was 53.7% in 2001, and increased to 63.1% in 2010. In both years, higher annual family income (over 6 million yen) was associated with parents’ attitude towardstheir infant’s daily life rhythm (odds ratio [OR] 1.43, 1.58; 95% confidence interval [CI] 1.29–1.58, 1.38–1.80; p<0.001, in respective years). Working mothers under childcare leave were more inclined to maintain their baby’s daily rhythm as compared with nonworking mothers (OR 1.22, 95% CI 1.15–1.30, p < 0.001;OR 1.16, 95% CI 1.10–1.22, p < 0.001, respectively). In situations where there were older sibling(s), parents were less likely to maintain a daily rhythm for their infant (OR 0.80, 95% CI 0.77–0.83, p < 0.001;OR 0.49, 95% CI 0.47–0.51, p < 0.001, respectively).

Conclusion: Family income and the working status of mothers were associated with parental attitudes towards maintaining infant’s daily life rhythm in this study.

Osawa E, Hayashi T, Kawashima TK (2015) Associated Factors for Maintaining Infants’ Daily Life Rhythm. Ann Pediatr Child Health 3(4): 1062.

•    Child rearing
•    Parental awareness
•    Infant
•    Daily life rhythm
•    Population-based survey

It is believed that keeping a daily rhythm of life for children improves their development. Indoor entertainment, such as online gaming or using computer programs, reduces physical activity among children and can sometimes affect their sleep– wake cycles. Evidence suggests that sleep disruption affects children’s cognitive development, regulation of affect, attention, health outcomes, and overall quality of life. It is suggested that practical measures for good sleep and behavioral treatments have beneficial effects on secondary outcomes such as child daytime functioning and parental well-being [1,2]. It has been reported that sleep disruption in early stages of infancy (within 1 year old) has associations with sleep difficulties at 6 months and night waking at 12 months [3]. Another study showed anassociation between sleep disturbance and bedtime settling strategies in the first 12 months, and affective and externalizing disorders at 5 years of age [4].

Regarding the association between child-rearing practices at home and child development, maternal employment outside the home has an influence on a child’s life in areas such as child health, socioemotional behavior, and learning achievement. There are studies reporting that the employment status of mothers was not associated with their children’s health [5]. Some studies imply only small differences in preschool development between children of working mothers and nonworking mothers [6,7], while other studies report that early maternal employment produced a negative impact on child development [8]. Since the 1980s, the number of women working outside the home who are in their late 20s and early 30s has increased in Japan [9]. Therefore, parental awareness of the benefits of keeping a daily life rhythm in early infancy is essential to benefit their child’s daily functioning and development. This study aims to examine the factors associated with the attitudes of parents of infants about 6 months of age, with respect to maintaining their child’s daily life rhythm.

We used public open data of the 2001and 2010cohorts of the Longitudinal Survey of Newborns in the 21st Century, which is a population-based birth cohort study that has been conducted annually since 2001 by the Ministry of Health, Labour and Welfare of Japan. The annual surveys investigate parental socioeconomic characteristics, child-rearing conditions, and awareness about childrearing. The sample chosen from the surveys was selected based on birth registration records of vital statistics. Questionnaires were sent and collected by mail.

In this study, we extracted cross-tabulated data from the first survey of the 2001 and 2010 cohorts, which target the parents of 6-month-old infants [10]. From the survey questions, we selected items asking which child-rearing behaviors parents were aware of. There are six options and multiple answers are permitted: 1) talk often to their baby; 2) hold their baby often; 3) allow their baby to listen to music often; 4) take their baby outside often; 5) maintain a daily rhythm for their baby; and 6) other. We used the answer for “maintain infant’s daily rhythm” as an outcome variable in analysis.

Independent variables were the mother’s age, number of siblings, family structure, mother’s work status, father’s involvement in childrearing and housework, and parents’ annual total income. Regarding involvement of the fathers in childrearing and housework, the survey question asked, “How often does the father do the following activities of childrearing or housework?” Child-rearing activities were: 1) feeding; 2) diaper changing; 3) bathing; 4) putting the baby to sleep; 5) playing with the baby; and 6) taking the baby outside. Housework activities included: 1) cooking; 2) clearing the table after meals; 3) cleaning the house; 4) doing laundry; 5) taking out the trash; and 6) shopping for daily needs. For all topics, parents were to select one option from the following: always (3 points), sometimes (2 points), rarely (1 point), or not at all (0 points). Finally, each score was summed up and the total was categorized as either active involvement (18– 12 points), intermediate involvement (11–6 points), or inactive involvement (5–0 points).

The odds ratio (OR) and 95% confidence intervals (CI) were calculated from cross-tabulated data using a logistic regression model to assess the association between parental awareness about maintaining a daily life rhythm for their infant and childrearing and the family’s living conditions. IBM SPSS Statistics 22 version was used for all analyses.

Outlined results of the 2001 and 2010 surveys are summarized in Table1. The target of investigation for the 2001 cohort was 53,575 surveys and 43,767for the 2010 cohort. Response rates were 87.7% (47,010) in 2001 and 88.1% (38,554) in 2010. The average age of mothers and fathers, respectively, was 29.4 and 31.6 (2001) and 30.9 and 32.8 (2010). The percentages of mothers in their 20s was 45.9% (2001) and 34.2% (2010), 51.2% (2001) and 60.0% (2010) for mothers in their 30s, and 1.9% (2001) and 4.5% (2010) for mothers in their 40s or older. Nonworking mothers represented the majority in both years (73.5% in 2001 and 63.7% in 2010). There was not much difference in the distribution of parent’s total annual income between 2001 and 2010. In 2001, 53.2% and 63.0% (2010) of parents had awareness about keeping a daily life rhythm for their baby. Regarding the fathers’ involvement in childrearing, 40.1% (2001) and 41.8% (2010) were actively involved; fathers’ involvement in housework was 9.8% (2001) and 17.0% (2010).

Table 2 shows ORs and 95% CIs for parental awareness about maintaining a daily rhythm for their infants, using a logistic regression model. In both 2001 and 2010, working mothers under childcare leave were more attentive to their baby’s daily rhythm as compared with nonworking mothers (OR 1.22, 95% CI 1.15–1.30, p < 0.001; OR 1.16, 95% CI 1.10–1.22, p < 0.001, in respective years). In families with older sibling(s), parents were less likely to maintain a daily rhythm for the infant (OR 0.80, 95% CI 0.77–0.83, p < 0.001; OR 0.49, 95% CI 0.47–0.51, p < 0.001, in respective years).

The involvement of fathers in childrearing and housework was not significantly associated with maintaining infants’ daily rhythm in both survey years. Higher annual family income (over 6 million yen) was associated with greater parental awareness about infants’ daily rhythm (OR 1.43, 1.58; 95% CI 1.29–1.58, 1.38–1.80; p<0.001, in respective years).

First, the results of this study suggest that total annual income is associated with parental awareness about maintaining a daily life rhythm for their baby. It has been reported that the level of family income influences child health and child behavior [11]. Our results suggest an association between family income and parental awareness of child-rearing activities that may lead to outcomes of child health and child behavior.

Second, in this study, working mothers were more likely than nonworking mothers to be aware of the importance of maintaining their baby’s daily rhythm. Empirically, it is considered that working mothers try to keep their babies on a regular schedule. In addition, when working mothers are under childcare leave, it is possible that they use their time to take care of their baby instead of doing other work. This study did not find a distinction between working mothers with full time/regular employment and those with part time/non regular employment. However, a previous study showed that working mothers with full time/regular employment were more likely to report job pressures and inflexible work schedules and to experience more strain related to work and family, whereas those with part time/non regular employment were more likely to face financial difficulties [12]. It has also been reported that mothers employed part time perceived less work–family conflict than mothers employed fulltime [13]. Further analysis with more details about maternal working conditions, which were not included in this study, is needed.

Interestingly, against our hypothesis, the current study showed that in families in which the infant had older sibling(s), parents were less likely to maintain a daily rhythm for the infant. This result might reflect the parents’ try to establish a daily rhythm for the siblings rather than for the infant.

In addition, the involvement of fathers in child rearing and housework was not associated with parental awareness about infant daily life rhythm in this study. Previous studies using the Longitudinal Survey of Newborns in the 21st Century (2001– 2002) have indicated that infants who experienced a high degree of paternal childcare involvement at 6 months were less likely to suffer from all unintentional injuries at 18 months than those who received a low degree of paternal childcare involvement [14]. However, the findings of our study, which analyzed cross-sectional data of infants at 6 months of age, suggest that the degree of attention paid to the infant’s daily life might rely on the parents’ lifestyle before having a baby.

This study had some limitations. First, we used public data; therefore, advanced analyses were not conducted. Second, as mentioned above, differences between full-time and part-time working mothers were not considered because working conditions (time spent at work per day or per week) were not included in the analyses. Further study and analysis is required to examine the factors influencing the maintenance of infants’ daily life rhythm.

Table 1: Outlined results of the Longitudinal Survey of Newborns in the 21st Century, in 2001 and 2010.

Table 2: OR and 95% CI for parental awareness of infant’s daily life rhythm, using logistic regression model.

In this study, we found common factors with respect to parental awareness about maintaining a healthy daily rhythm for their infant. In both survey years, higher total annual parental income and maternal employment status corresponded with more attention paid to infant daily rhythm. The involvement of fathers was not confirmed to be related to this awareness.

This study was funded by Health and Labour Sciences Research Grants (H25-004 Research on global health issues, 2014–2015).

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