The Effect of Infancy Childcare Center Use and Maternal Employment ...

Asian Social Work and Policy Review 10 (2016) 130–141

ORIGINAL ARTICLE

The Effect of Infancy Childcare Center Use and Maternal Employment on Toddlers’ Language Development in South Korea Jaejin Ahn1 and Joan P. Yoo2 1

Department of Social Welfare, Gachon University, Seongnam, Gyeonggi-do, South Korea; National University, Gwanak-gu, Seoul, South Korea

2

Department of Social Welfare, Seoul

Using first to fourth wave data of the Panel Study of Korean Children (PSKC), this study explores the effects of childcare center use, maternal employment, and other child and familial characteristics on the language development of toddlers in Korea. Among the 2078 families with children in the PSKC, those who completed the Receptive and Expressive Vocabulary Test at the fourth wave were selected, and a small number of disabled or prematurely born children were excluded. In addition, to clarify the effects of maternal employment, families with mothers who were either employed or unemployed for three consecutive years during the child’s infancy were selected. Regression analysis showed that neither childcare center use nor maternal employment during infancy had significant effects on toddlers’ expressive and receptive vocabulary at the fourth wave. Family characteristics, such as household poverty and maternal education level, as well as child characteristics, such as gender and birth order, had significant effects on expressed vocabulary. However, only children’s gender significantly affected the receptive vocabulary level of toddlers. Keywords infancy childcare; maternal employment; language development; the Panel Study of Korean Children doi:10.1111/aswp.12083

It is well known that infancy, which refers to the first 3 years of a child’s life, is a critical period for children’s development. Further, among the factors affecting the growth of children, primary caregivers principally responsible for caring for the child have the most important influence during these early years (Ahn & Shin, 2013). Based on this knowledge, there has been a strong preference for a mother’s care, at least during infancy. In addition, if non-maternal care is necessary, kinship care is regarded as the best alternative. According to The 2012 National Survey on the Current Status of Child Care in Korea, for children younger than 1 year, most participants responded that kinship care, such as care by grandparents (82.6%) or relatives (4.1%) are the best alternatives to parental care, and 5.6% responded that no one can substitute parental care at this stage of life (Suh et al., 2012). Only 6.3% regarded a childcare center as a desirable type of non-parental care. The strong preference for kinship care as non-parental care was consistent until children reached 2 years of age; thereafter, this preference weakened. Care by grandparents as the best alternative decreased to 30.6% for 2-year-old children and the preferences for a childcare center (38.6%) or a home childcare center (24.8%), both officially licensed types of childcare centers in Korea, dramatically increased (Suh et al., 2012). Contrary to this general belief, however, there has been a dramatic increase in childcare centers providing care for infants in Korea over the last decade. In 2014, 66% of infants (aged 0–2) were cared for in Correspondence concerning this article should be addressed to Joan P. Yoo, Department of Social Welfare, Seoul National University, 16-632, Gwanakro 1, Gwanak-gu, Seoul Korea. Email: [email protected] Acknowledgements: This research was supported by Gachon University Research Funds (GCU-2014-0140), awarded to Jaejin Ahn.

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© 2016 John Wiley & Sons Australia, Ltd

Jaejin Ahn and Joan P. Yoo

Toddlers’ Language Development in South Korea

childcare centers (Ministry of Health and Welfare, 2014). This rate is quite high considering that the employment rate of mothers with infants in Korea increased from 23.8% in 2002 to 34.2% in 2012, which is still low compared to the average employment rate of women in Korea (Suh et al., 2012). Many factors may contribute to this upward trend of infants’ presence in childcare centers, such as the increase of the female workforce in the labor market and financial support from the government for childcare center use. Although parental leave of 1 year is set by law for employees with children aged eight or younger (before 2014, aged 6 or younger), only 12% used parental leave in 2012 and the average duration of leave was only 7.9 months (Oh, Kim & Oh, 2012). According to Oh et al. (2012), the main reason for not using parental leave was the non-friendly working environment for working parents (30.0%), followed by financial reasons (22.6%), as maternity or paternity leave allowance only covers 40% of ordinary wages. Thus, working parents had to rely on childcare centers to keep their employment. However, there is a more fundamental reason that explains this trend. The Korean government encouraged the use of childcare centers for very young children with the establishment of a free childcare policy. In March 2012, the government declared a universal childcare policy for all infants and toddlers, regardless of household income, and the use of childcare centers for infant care increased to 62% from 54% the previous year. The increase in the number of infants in childcare centers was followed by criticism from the public, as well as from academia. In practical terms, parents who neither needed nor wanted to use childcare centers for their infants felt deprived of their privilege, and started to use such centers for a short time (2–3 hours) during the day, thus causing a shortage of care at childcare centers. As a result, those who were in urgent need of utilizing childcare services –mostly working mothers – could not access such services (Korea JoongAng Daily, 2012). This free childcare policy, which saw a substantial increase of infants being cared for in childcare centers, drained the government budget and was criticized as a bad example of “welfare populism.” Therefore, the following year, the Korean government introduced cash subsidies for families with infants who did not attend childcare centers, encouraging parental care for infants. However, the rate of infants in childcare centers remained high. For example, the rate of infants (0–2 years) in 2009 was 41.6%, which has increased to 66.1% in 2014 (Ministry of Health and Welfare, 2014). In the literature, evidence of the effects of childcare use during infancy is mixed. Researchers in childhood development blamed policy-makers for not considering the risks of utilizing childcare centers during early childhood (Hwang, 2013), as there is evidence that quality childcare is beneficial for children’s development, especially in low-income families (Burchinal, Roberts, Nabors & Bryant, 1996). Particularly in infancy, responsive and stimulating interactions between infants and adults have been found to enhance an infant’s cognitive, language, and social development. The interactions are often found to be more effective when provided by caregivers at home rather than in group care settings. The Organisation for Economic Co-operation and Development (OECD) also recommends parental care for infants, as infancy is a critical period for attachment formation with the caregiver. Thus, the OECD’s suggested rate of utilizing childcare centers is less than 30% for infants (Hwang, 2013). Discrepancies between the general preferences for maternal care and the substantial increase in the actual use of childcare for infants raises public concerns on the psychological well-being and developmental progress of infants in childcare centers. Further, whether employed or unemployed, mothers with infants in childcare centers may suffer from self-reproach or implicit disapproval from others. Therefore, this paper attempts to provide empirical evidence for the effects of attending childcare centers during infancy on the language development of toddlers in South Korea. The reason we focus on the language development of toddlers is that language development is one of the key domains of childhood development, which predicts the other aspects of development (Lee, 2011). In addition, because of the limitations of secondary data analysis, we could not find a better indicator for child development in the data set. © 2016 John Wiley & Sons Australia, Ltd

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Given the Korean context where childcare centers have increasingly provided care for infants, it is essential to consider whether the traditional belief that infants should be cared for at home is still valid. This study seeks to address this question using empirical research.

Literature review Language development is one of the key domains of childhood development and children’s language develops rapidly during infancy. Moreover, children’s language development is known to be closely related with other aspects of childhood development, such as intelligence, and social and motor skills, and such correlations are more significant at the early stages of language acquisition and communication development (Lee, 2011). Thus, children’s level of language ability was selected in this study as a key indicator of their development status. Newborn babies, for the most part, express their intentions through cries or gestures until about the age of one, when they begin to develop their first spoken language and verbally communicate with others. Toward the end of infancy, children can understand and express the basic grammar of their native language (Owens, 2005; Rossetti, 2001, cited in Lee, 2011). During language acquisition, both the quantity and quality of language input is important. The total amount of speech heard by an infant is highly correlated with language outcomes. Even more important is the quality of language input. A recent study examining the relationship between the quality of language input and language outcomes highlights the importance of social context, and particularly caregiver responsiveness to the infant (Golinkoff, Can, Soderstrom & Hirsh-Pasek, 2015). Previous studies on the language development of young children show that child, family, and childcare characteristics are important predictors of children’s language development (Burchinal et al., 1996). An ecological system perspective (Bronfenbrenner, 1979), widely adopted as a theoretical framework for childcare research in relation to different contexts, such as child, family, and societal characteristics, is applied to the present study as the language development of the child depends not only on the context of family, but also on the broader social and cultural circumstances, such as the national childcare policy or educational program (Sylva, Stein, Leach, Barnes & Malmberg, 2011; Sylva et al., 2007). Child characteristics The effects of gender and birth order on children’s language development have been the subjects of numerous studies. In a review article on gender differences and verbal ability, Berglund, Eriksson, and Westerlund (2005) concluded that differences between girls and boys in the early years might vary depending on age, time, and culture. When gender differences are reported, girls are found to have better verbal ability than boys (Berglund, Eriksson & Westerlund, 2005). The superior language development of girls was found in studies conducted in diverse countries. Girls scored higher on language outcomes at 18 months in Sweden, Norway, and England (Berglund et al., 2005; Schjølberg, Eadie, Zachrisson, Øyen & Prior, 2011; Sylva et al., 2011). In Korean studies, gender was also found to be closely related with the language development of infants and toddlers (Chang, 2004; Kim, 2008; Lim, 2015). The effects of children’s birth order on language development still seem to be widely debated (Lowry, 2012). Hoff-Ginsberg (1998) found that while later-born children had better conversational skills, first-born children had better developmental outcomes in relation to vocabulary and grammar. Bornstein, Leach and Haynes (2004) found that associations between birth order and receptive and expressive vocabulary competence may differ according to the type of assessment (i.e. maternal reports vs. standardized testing and direct observation). In a study by Schjølberg et al. (2011), the existence of older siblings predicted low scores on language outcomes at 18 months of age. Other studies did not report any difference in language development between first-born and later-born children (Berglund et al., 2005; Oshima-Takane, Goodz & Derevensky, 1996), despite the small differences. Language differences between first-born and second-born children are often attributed to caregivers 132




spending more one-on-one time interacting with and giving more attention to their first-born child, or to the benefits gained from younger children in overhearing conversations between caregivers and other siblings, as well as multiparty conversations (Lowry, 2012). Caregiver and family characteristics Social interactionist theory emphasizes the role of social interaction between developing children and adults who create the environments for their children’s language acquisition process. Bruner (1983) refers to parents’ Language Acquisition Support System (LASS), which contributes to the language development of children. This includes parental reactions to a baby’s babble, games that stimulate the child’s language acquisition such as peekaboo, and the use of “motherese,” or the language and tone that mothers typically use when speaking to their baby (Chung, 2013). Based on the social interactionist theory of language acquisition, we can assume that the more the caregiver interacts with the child, the better his/her development outcomes in language will be. Such a hypothesis is supported by empirical evidence. To examine the effects of maternal and infant interactions on language development, Ko and Oh (2006) compared infants reared at home with infants in institutional care. They found that infants cared for at home scored higher than infants in institutional care for both receptive and expressive language, and this result indicates the deleterious effects on the language development of infants deprived of maternal interaction (Ko & Oh, 2006). Factors, such as mothers providing more opportunities for stimulation and with a higher level of maternal sensitivity also predicted vocabulary scores among infants (Sylva et al., 2011). In the same vein, maternal employment, as well as the use of childcare centers, reflect a lack of maternal interaction with infants, as the time spent with the infant must be reduced for employed mothers. In addition, a positive association between parental socioeconomic status (SES) and the verbal abilities of children has been reported in previous research. After reviewing several studies that investigated this association, Berglund et al. (2005) concluded that there is some evidence that the parents’ SES is in fact associated with toddlers’ language abilities, and this association will remain or accelerate during childhood. At as early as 18 months, significant disparities in vocabulary and language processing efficiency were already evident between infants from families with higher and lower SES, and by 24 months there was a six month gap between the two groups in processing skills (Fernald, Marchman & Weisleder, 2013). Low maternal education also predicted low scores on language development in Norwegian infants (Schjølberg et al., 2011). In a Korean study, the SES of parents – or overall family income and parental education – was again found to be a significant predictor of the expressive and receptive language development of 3-year-old toddlers (Lim, 2015). Childcare characteristics Both quantity (time spent in childcare settings) and quality of childcare should be considered when the effects of childcare centers are examined. The results of studies on early care and education (ECE) and child development now point to the conclusion that the quality of child-adult interactions in ECE settings is the most important source of variation in child outcomes, although the amount of time spent in these settings also matters (Phillips & Lowenstein, 2011). With respect to children’s language development, the effects of childcare appear mixed (Sylva et al., 2011). The National Institute of Child Health and Human Development (NICHD), which followed children in the United States to determine how childcare experience relates to cognitive and language development from birth to age three, reported that the cumulative number of hours in non-maternal care did not predict the outcomes, and the overall quality of childcare was only modestly related to cognitive and language outcomes at the ages of 15, 24, and 36 months (National Institute of Child Health and Human Development, 2000). Further, children in exclusive maternal care did not differ systematically from children in childcare centers. Thus, the NICHD (2000) concluded that there was no evidence that early and extensive care is either deleterious or advantageous for a child’s cognitive and language abilities in both advantaged and © 2016 John Wiley & Sons Australia, Ltd

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disadvantaged groups. In an English study that examined both the quantity and quality of non-maternal care, more hours of group care, as well as the quality of non-maternal care, were significantly related to higher cognitive development at 18 months, but not language development after controlling for sociodemographic and maternal care characteristics (Sylva et al., 2011). On the other hand, positive, long-term effects of early day-care center use on children’s cognitive abilities, including language, have been reported in Swedish children (Andersson, 1989, 1992; Broberg, Wessles, Lamb, & Hwang, 1997, cited in Berglund et al., 2005). One Korean study explored the effects of childcare on the language development of 1 to 3-year-olds, and found that the infants in childcare centers were more advanced in their language development than infants reared at home (Lee, Lee & Lee, 1997). The results of these studies are in contrast to the traditional belief in our society that the optimal method of early childcare is home care by parents or relatives. Some studies indicate the more beneficial effects of high quality care for low-income families. O’Connell and Farran (1982) reported that when infants in low-income families receive high-quality childcare, their language development tends to be better than their home-reared counterparts (as cited in Burchinal et al., 1996). Further, high-quality care has been shown to be related to higher measures of language development among infants from African-American families, even after controlling for child and family characteristics (Burchinal et al., 1996, 2000). Although both quantity and quality of childcare are important predictors of child language development, service quality measures were not provided in the data set. Thus, this study focuses on the effects of childcare center use and maternal employment during infancy on the language development of toddlers after controlling for child and family characteristics. Based on the theoretical framework of the ecological system perspective, child, caregiver, family, and childcare characteristic variables were selected as predictors of children’s language development.

Method Data and sample This study uses the first through fourth wave data from the Panel Study of Korean Children (PSKC), a birth cohort panel of 2078 infants born in 2008. The PSKC is the first panel of newborns in Korea and was constructed and maintained by the Korea Institute of Child Care and Education (KICCE), the governmental research institute for early childhood education and care policies in South Korea. The PSKC used a stratified multistage sampling, where the primary sampling unit was hospitals with more than 500 births per year, and the secondary sampling unit was families who gave birth in those hospitals from April to July of 2008 (Shin, Ahn, Lee, Song & Kim, 2008). Of 2561 families recruited in these hospitals, 2078 families participated in the PSKC. The first wave data were collected when the majority of babies were four to eight months old, and the data were collected annually as the children grew. Among the 2078 families with children in the PSKC, the families whose children completed the Receptive and Expressive Vocabulary Test (REVT) at the fourth wave were selected, and a small number of children with disabilities or who were prematurely born were excluded. Although disability or preterm birth could be significant predictors for children’s language development, each group constituted less than 3% of the sample, making it impossible to include these factors as control variables (Schjølberg et al., 2011). To clarify the effects of maternal employment, families with mothers who were either employed or unemployed for three consecutive years during the child’s infancy were also selected. We did not include mothers with intermittent employment history as it made interpretation of the results more confusing.1 As a result, a total of 1216 children were included in the analysis. 1

We conducted a sensitivity test and found that the inclusion of mothers with intermittent employment history did not make any significant changes to the results. 134




Measures Children’s language development The REVT was used as an indicator of children’s language development (Kim, Hong, Kim, Chang & Lee, 2009). A trained interviewer contacted the caregiver and visited the child’s home to administer the REVT test. The receptive language test consists of 185 items with 98 nouns, 68 verbs, and 19 adjectives and adverbs. The expressive language test consists of 185 items with 106 nouns, 58 verbs, and 21 adjectives and adverbs. Originally the starting point among items is different depending on the child’s age. However, to simplify the testing process, all children in the sample received the same first question after consultation with the authors of the scale (Kim et al., 2012). When a child’s answers were incorrect for six out of eight consecutive items, the upper threshold was set and items over the threshold were considered incorrect answers. The raw score was calculated by subtracting the number of incorrect answers from the item number of the upper threshold. Maternal employment during infancy To clarify the effects of maternal employment, the employment group consisted of mothers who were consecutively employed from the first to the third wave survey, while the unemployment group consisted of mothers who were unemployed from the first to the third wave survey. Use of a childcare center during infancy The duration of childcare center use was measured using one question: whether the child was attending a childcare center at the time of the survey. If the child did not attend a childcare center for all three surveys, the duration of time spent at a childcare center was coded zero. If the child attended a childcare center during one of the three surveys, it was coded one. As such, the duration of childcare center ranged from zero (no use) to three. Family poverty To define the families in poverty, an income-to-needs ratio was calculated for each family by dividing family income by the minimum cost of living. The families with an income-to-needs ratio of less than two were defined as families in poverty. All control variables were extracted from the first wave of data. Maternal education level The education level of the mother was measured using an ordinal scale. The answers consisted of “up to high school” (1), “junior college graduate” (2), and “university graduate and above” (3). Gender and birth order of the child The gender of the child was coded as a dummy variable. Birth order was coded as the number in the birth order except for fifth and later-born children who were all coded as five. Data analysis As this study focused on whether the use of childcare centers or maternal employment during infancy affected the language development of toddlers after considering child and family contexts, regression analysis was used to analyze the data. Thus, Model 1 included two independent variables (childcare use and maternal employment during infancy) and child and family characteristics as control variables (child’s gender, birth order, family poverty, and maternal education). In Model 2, the interaction term between childcare use and family poverty was created and entered, as previous research indicates that early childcare use is beneficial, especially for disadvantaged children. Moreover, the needs and reasons for working may differ based on a family’s economic status, which could also impact the effect of a mother’s employment on a child’s language development. Thus, the interaction term between the poverty status of the family and maternal employment was included in the model. © 2016 John Wiley & Sons Australia, Ltd

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Results Sample characteristics Descriptive statistics revealed that more than half of the children (59.6%) did not attend a childcare center during their infancy, and the majority of children who did attended for 1 year of their infancy (Table 1). Only 27.2% of mothers were employed during their child’s infancy, while the majority of mothers stayed at home. In addition, 37.3% of families were below the income-to-needs ratio of two, and the rate of boys and girls appeared to be similar in the sample. More than half of the children were second and later-born children. Most mothers had some college education. Looking at the group differences between families with working and non-working mothers, most of the demographic variables, apart from the gender of the child, were significantly related to maternal employment status. Children of working mothers tended to attend childcare centers during infancy, and for longer periods. Families with working mothers were less likely to be in poverty and working mothers were more likely to have a higher educational level. Birth order reflected the number of children within a household. Working mothers tended to have fewer children than non-working mothers. The mean REVT scores are presented in Table 2. The scores for the receptive vocabulary test are more varied than those of the expressive language test. Factors associated with a toddler’s language development Tables 3 and 4 present the results of the regression model for the expressive and receptive language of toddlers in Korea. Model 1 consists of two independent variables (maternal education and duration of childcare center use during infancy) with control variables. The two interaction terms were added to Model 2. The results show that maternal employment and childcare center use during infancy did not affect the children’s language development at the time of the fourth wave survey, after controlling for child and family characteristics. Child and family variables had significant effects on the expressive language of the children. Boys scored lower on the expressive vocabulary test. Maternal education had a significant positive association with children’s expressive language, indicating that mothers with higher education are more likely to encourage the expressive language development of their children. Birth order also had significant effects on the expressive language of the children. The later-born children tended to score lower on the expressive vocabulary test. The adjusted r-square was 0.67, which means that Model 1 accounts for about 7% of the variation in children’s expressive language. Because differential effects of maternal employment and childcare use on children’s language development, based on a family’s economic conditions, could exist, we included the interaction effects of childcare use, employment, and poverty in Model 2. We found no significant interaction effects between childcare use and poverty, or employment and poverty on children’s expressive vocabulary. However, the effect of family poverty on expressive vocabulary, which was insignificant in Model 1, became significant, suggesting that there was a suppression effect in the previous model. According to these results, children in poor families whose mother is not working, accounting for the poverty and maternal employment interaction term, scored significantly lower on expressive language than their affluent counterparts. As presented in Table 4, childcare and family variables were not important predictors of the receptive language development of the children. Only a child’s gender was significantly associated with receptive vocabulary. The explanatory power of the regression model was also very low (less than 1%), indicating that other variables should be considered when trying to explain variations in the receptive language of toddlers. The findings suggest that different sets of variables need to be considered when examining factors associated with the receptive and expressive language development of children. Adding the interaction term between childcare use and family poverty, as well as employment and poverty in Model 2, did not improve

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Table 1 Descriptive statistics of study variables Total sample Variables Use of childcare center during infancy None 1 year 2 years 3 years Total Maternal employment during infancy Yes No Total Families in poverty Yes No Total Gender of the child Male Female Total Education level of mother Up to high school Junior college graduate University graduate and above Total Birth order of the child First Second Third Fourth Fifth or greater Total

Percentage in employed mothers

N

%

%

v2

712 400 70 34 1216

58.6 32.9 5.8 2.8 100.0

42.3 38.0 14.9 4.8 100.0

167.71 (3)***

331 885 1216

27.2 72.8 100.0

453 760 1213

37.3 62.7 100.0

24.3 75.7 100.0

603 613 1216

49.6 50.4 100.0

50.9 49.1 100.0

379 366 470 1215

31.2 30.1 38.7 100.0

22.8 26.6 50.7 100.0

58.058 (2)***

548 519 131 12 2 1212

45.2 42.8 10.8 1.0 0.2 100.0

49.1 42.0 8.6 0.3 0.0 100.0

11.994 (4)*

92.162 (1)***

0.060 (1)

*P < 0.05; ***P < 0.001.

the model fit. Furthermore, the interaction was not significant, and, therefore, the interaction effects were not supported in this study.

Discussion Utilizing first to fourth wave data from the PSKC, this study showed the effects of childcare center use, maternal employment, and other child and familial characteristics during infancy on the language development of toddlers in Korea. Regression analysis showed that neither childcare center use nor maternal employment during infancy had significant effects on toddlers’ expressive and receptive vocabulary at the fourth wave. This result is consistent with the National Institute of Child Health Human Development Early Child Care Research Network (2000) and Sylva et al. (2011) in that the early and extensive use of childcare centers is neither deleterious nor advantageous for a child’s cognitive and language development, © 2016 John Wiley & Sons Australia, Ltd

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Table 2 Scores of receptive and expressive vocabulary tests Vocabulary test Receptive Expressive

N

Mean

SD

Min

Max

1216 1213

33.40 29.76

15.84 13.65

0 0

95 68

SD, standard deviation.

Table 3 Results of regression model for expressive vocabulary Model 1 Variable Duration of care use Maternal employment Family in poverty Maternal education Child’s gender (boy) Birth order Care use * poverty Employment * poverty F (df) R-Square (Adj.)

B (SE) 0.107 (0.492) 0.499 (0.742) 1.347 (0.729) 2.231 (0.422)*** 3.071 (0.663)*** 3.229 (0.476)***

20.729 (6)*** 0.072 (0.068)

Model 2 Beta 0.006 0.018 0.048 0.135 0.112 0.166

B (SE) 0.063 (0.602) 0.462 (0.900) 2.578 (0.970)** 2.272 (0.422)*** 3.135 (0.663)*** 3.279 (0.476)*** 0.432 (1.024) 2.926 (1.576) 16.164 (8)*** 0.075 (0.070)

Beta 0.003 0.017 0.091 0.138 0.114 0.169 0.016 0.064

**P < 0 01; ***P < 0.001. SE, standard error.

which is inconsistent with other study results (Andersson, 1989, 1992; Broberg, et al., 1997 cited in Berglund et al., 2005; Burchinal et al., 1996, 2000; Lee et al., 1997; O’Connell & Farran, 1982). In addition, no evidence was found of the advantages of early childcare center use for children from low-income families, as the interaction effect between these two variables was not significant. This may be because of the fact that the quality of childcare was not considered in our study, as our main focus was to examine the effects of early childcare use. Moreover, there were few valid indicators for service quality in the data set. However, because of strict government regulation in Korea, the child-to-adult ratio, which is one of the most significant indicators of quality childcare, is assumed to be similar among all childcare centers. Maternal employment did not affect the language development of the toddler, even in cases where the mother was employed consistently during the entire infancy period. This result is contrary to our expectation that a lack of interaction with infants would be deleterious to their language development. Moreover, children in poverty benefited from their mother’s employment. Based on the interaction effect between maternal employment and poverty, children who lived in poverty and whose mothers were not employed scored lower on expressive vocabulary than other children. This may partially result from the various interactions that children with a non-maternal caregiver. It may be possible that comprehensive interactions between the caregiver or the teacher in the childcare center and the child explain this effect. Although there is a concern that infants in group care are less likely to experience one-on-one interaction, except for cases where there are only a few infants per adult and the teachers provide developmentally appropriate interactions with each infant in the class (Burchinal et al., 1996), the child-to-adult ratio in Korean childcare centers seems to make it possible for the teacher to compensate for the lack of infants’ interactions with their mothers. The Korean child-to-adult ratio in childcare centers meets the international standard. For children 138




Table 4 Results of regression model for receptive vocabulary Model 1 Variable Duration of care use Maternal employment Family in poverty Maternal education Child’s gender (boy) Birth order Care use * poverty Employment * poverty F (df) R-Square (Adj.)

B (SE) 0.642 (0.588) 0.145 (0.888) 0.893 (0.872) 0.894 (0.504) 2.479 (0.793)** 0.712 (0.570)

3.197 (6)** 0.012 (0.008)

Model 2 Beta 0.029 0.005 0.027 0.047 0.078 0.032

B (SE) 0.285 (0.721) 0.590 (1.080) 1.032 (1.162) 0.861 (0.505) 2.433 (0.795)** 0.698 (0.571) 1.066 (1.226) 1.401 (1.887) 2.519 (8)* 0.012 (0.008)

Beta 0.013 0.018 0.031 0.045 0.076 0.031 0.034 0.027

*P < 0.05; **P < 0 01. SE, standard error.

aged under one, the ratio is 3:1, with 5:1 for 1-year-olds, and 7;1 for 2-year-olds. In a Korean study that reported positive effects of early childcare center use on children’s language development, the teachers in childcare centers tended to show more advanced verbal interactions with infants than their mothers at home (Lee et al., 1997). Family characteristics, such as household poverty and maternal education level, as well as child characteristics, such as gender and birth order, had significant effects on expressive vocabulary. Girls scored higher than boys, and this finding is consistent with the results of previous research (Berglund et al., 2005; Chang, 2004; Kim, 2008; Lim, 2015; Schjølberg et al., 2011; Sylva et al., 2011). First-born children were more advanced in their expressive language than later-born children, and this result is consistent with Berglund et al. (2005), Hoff-Ginsberg (1998), and Schjølberg et al. (2011). This finding showed the advantages of language development for first-born children, but was inconsistent with findings of previous research that determined no difference between first-born and later-born children in terms of language development (Bornstein et al., 2004; Oshima-Takane et al., 1996). The SES of the parents, or the household income and maternal education of the family, was an important predictor of children’s expressive language development. Children from low-income families with lower maternal education tended to score lower on the expressive vocabulary test than children from families with higher income and higher levels of maternal education. These results are consistent with our expectation and the results of previous research (Berglund et al., 2005; Fernald et al., 2013; Lim, 2015; Schjølberg et al., 2011). One of the interesting findings of this study is that none of the variables were significant predictors of the receptive language development of children, except for the children’s gender. Further, the low level of explanatory power of the regression model indicates that a different mechanism was working with respect to the child’s receptive language development. Thus, the variables explaining the variations in the receptive language of the toddlers should be explored in further research. The quality of interaction between caregiver and child, or the quality of childcare, neither of which were included in our study because of limitations in the data, may play a role. The results of this study show that there is no empirical evidence to indicate that early childcare center use and maternal employment during infancy have harmful effects on children’s language development, although this result is not consistent with the general belief in Korean society that an infant should be cared for at home, preferably by the mother (Ahn & Shin, 2013; Suh et al., 2009, 2012). This result may partly result from the improvements in childcare quality over the last decade. As childcare center use has expanded, the Korean government has made an effort to ensure the quality of childcare centers by © 2016 John Wiley & Sons Australia, Ltd

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regulating the structure of childcare quality through measures regulating class size, child-to-adult ratios, and teacher qualifications, as well as the introduction of a childcare center accreditation system. Currently, most childcare centers (except for those that are newly established) have accreditation from the government. The results of this study showed that both the guilt that working mothers may experience and criticism toward non-working mothers who utilize childcare center services are not based on empirical evidence. Language development is only one of the domains of childhood development. The effects of early childcare center use and maternal employment on other areas of childhood development should be studied more extensively before reaching a conclusion.

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