The long-term study in Germany, the KiGGS study by the Robert Koch Institute (German Health Interview and Examination Survey for Children and Adolescents KiGGS Wave 2), provides representative nationwide data on young people’s health in Germany. By using a screening questionnaire (Strengths and Difficulties Questionnaire, SDQ) including sub-scales for emotional symptoms, peer relationship problems, conduct problems and hyperactivity/inattention, the nation-wide results show that 20.9% of the 3–5-year-olds (95%-confidence interval: 17.5–24.7) are affected by psychopathological problems and psychosocial impairments . The results of the KiGGS Wave 2 also show that children from families with a lower socio-economic status are more affected by mental health problems than children from families with a high or middle socioeconomic status . Other research also found out that children who grow up in poverty more frequently have delays in social and communication skills. In addition, these children more often display behavioral problems , lower social skills – especially self-regulation skills [3, 4] and reduced school-readiness .
Moreover, gender differences were found in the KIGGS Wave 2, e.g. boys show a higher risk for behavioral disorders, hyperactivity and peer-problems, whereas girls have a higher risk for emotional problems . Several studies have shown evidence for a link between gender and children’s development [3, 6, 7].
Our investigation was based on a pilot-study, which revealed for 15.4% of the children tested at preschools that there were reasonable findings with regard to their social development, while the results for another 7.7% were inconclusive . Further risk factors include linguistic and cognitive developmental delays and male gender . Language skills are associated with social-emotional competencies, the ability to comply with demands and to build up positive relationships [2, 8, 9]. Language skills are necessary for social interactions. In consequence, children with specific language impairments are more often at risk for developmental delays in their social development .
In addition, in every situation or activity linguistic, cognitive, motor and social-emotional skills were promoted in a parallel way. For example, while playing soccer the children have to follow rules, have to run and have to communicate with their team . In preschools, social behavior can be tested in and through sport activities with others. In addition, pedagogically guided and structured exercises offer enable specific situations in which taking and negotiating roles, agreeing on rules, making contact and cooperative behavior are relevant .
Previous research show that effective interventions provide the chance to reduce the school readiness gap which is associated with socioeconomic disadvantage . For example, in Preschool PATHS, a randomized clinical trial evaluating an adaptation of the Promoting Alternative Thinking Strategies curriculum (PATHS) for preschool-age children in Head Start, 287 children were followed for 1 year, with skills assessed at the beginning and end of that year. The evaluation showed that children in the intervention group had higher emotion knowledge skills and were rated by parents and teachers as more socially competent compared to control peers .
Social skills as valid predictors for school-readiness and -success
There is a strong evidence that social skills can be considered as valid predictors for school- readiness and subsequent success at school [2, 13]. In general, children with behavioral problems and less social skills have problems to control their emotions and have less efficient social problem-solving strategies [8, 14]. Social skills are associated with a cooperative and successful interaction with peers and more supporting friendships [2, 7]. Furthermore, children with lower social skills have on average less empathy and self-regulation skills .
Socially competent children are able to pay more attention to their academic tasks, are able to plan better and to benefit more from instructions by teachers [2, 7]. Children with lower social skills tend to participate less in class, are rather non-compliant with rules and less accepted by peers and teachers [2, 5, 15]. One’s school career has been shown to be dependent on learning motivation, learning behavior and learning problems . All of these factors are associated with social skills and, hence, disorders in this domain are negatively associated with one’s school career and even more so with success at school [2, 14, 16, 17]. On the other hand, social-emotional skills are important predictors of school achievement .
Children at risk of deficits in their social development have a higher risk of ruining relationships in the future and also of academic failure and violence . A recent study of the OECD confirms that social-emotional skills are the most predictive skills of success in a wide range of important life outcomes, e.g. academic achievement, job performance, occupational attainment, health, longevity or personal and societal well-being . Furthermore, a lack of these skills regularly correlated with unfavorable long-term outcomes such as an increased chance of unemployment, divorce, poor health, criminal behavior and imprisonment [19,20,21].
Day-care in Germany
In Germany, preschools (in Germany called “Kindergarten”) are institutions for early childhood education and care for young children from age three to school entry. According to § 22 SGB (Social Code) VIII, the institution preschool has the aim to
promote the development of every child into a responsible and sociable personality,
support and supplement the family care and education and
help the parents to arrange their work and parenting.
In preschools in Mecklenburg-Western Pomerania there are about 13.7 children per preschool-teacher, that is 4.5 children more than in Germany as a whole (1:9.2, ).
Due to the high utilization rate of preschools in Mecklenburg-Western Pomerania (in 2017: 0-to-3-year-olds: 56%, 3-to-6-year-olds: 95.2% ) preventive activities implemented in this setting have the chance to reach most of the children in Mecklenburg-Western Pomerania, including children with a lower socioeconomic status, without stigmatization.
The time spent in preschools is the period in which significant social skills are developed . Prior to school entry, cognitive abilities and cognitive control (attentional performance and task persistence) have a great predictive power of future achievement outcomes, while prosocial behavior positively influences the learning motivation and the self-concept. Therefore, this setting provides a chance to integrate prevention activities to promote social skills. Moreover, a preschool is attended by most children (for at least 3 years) and therefore provides a relevant setting for long-term prevention activities .
Preventive activities can reduce social disparities and improve equal opportunities for school-readiness . An appropriate promotion of competences requires a systematic and standardized observation and documentation of developmental dynamics . Therefore instruments for developmental monitoring have become more important . Sinzig & Schmidt  demand that preschool teacher should monitor the children’s development.
The federal state law for child day-care and preschools in Mecklenburg-Western Pomerania
The federal state law for children’s day-care and preschools in Mecklenburg-Western Pomerania is designed to reduce social inequalities  by focusing on preschools in social hotspots. According to a definition of social hotspots from 1979, social hotspots in Germany are areas in which factors that determine the living conditions of their residents negatively occur more frequently. Especially, these factors influence the development opportunities of children and adolescents negatively .
The federal state law provides additional financial funds for the individual as well as group support for children with developmental delays in their motor, linguistic-cognitive or social development.
The federal state law for children’s day-care and preschools in Mecklenburg-Western Pomerania selects the preschools as follows: the youth welfare offices of each region in Mecklenburg-Western Pomerania determine the specific amount of preschool-fees that was covered by the state for each preschool. Subsequently, those in charge of preschools with an amount above the average are informed about the opportunity to receive additional funding according to the law (at least an annual amount of EUR 20,000 for preschools attended by < 50 three to 6 year olds, or at least an annual amount of EUR 40,000 for preschools attended by ≥50 three to six year olds, respectively) – the participation is voluntary for the preschools .
Mandatory criteria for claiming these benefits and funds from the State of Mecklenburg-Western-Pomerania is an annual application of a valid, standardized, objective, and reliable developmental screening instrument to monitor the development and to detect developmental delays (“Dortmund Developmental Screening for Preschools DESK 3-6”) [30, 31]. Another mandatory criterion for claiming additional funds is the participation in a scientific evaluation within the framework of the legislation for a standardized, objective, and valid assessment of developmental delays. Based on the result of the screening instrument, the targeted and individualized interventions of children at risk take place in the preschool .
Purpose of the study
For the initiation of early individual intervention strategies, it is important to monitor the development and to detect developmental delays early on. For the planning and implementation of early prevention both valid prevalence rates and possible risk factors are essential . The present paper reports the age-specific prevalence rates of developmental delays with regard to the social development of socially disadvantaged children aged from 3 to 6 years old in a total of 90 preschools in Mecklenburg-Western Pomerania. Further, we analyze the relationship between potential risk factors and the social development using a large sample size. The results help define and plan evidence-based intervention strategies in Mecklenburg-Western Pomerania.