Compared to twenty years ago, the digital media environment has flourished (1, 2). Children are growing up with both traditional electronic media (television) and new interactive media, such as entertainment gadgets (game consoles, video/DVD/Blu-ray players, and tablets), work devices (personal computers and laptops), multi-functional devices (smartphones) and not to forget electronic book readers. Infants today may learn to use digital media before they learn to walk.

However, premature contact and overuse of digital media may disturb an infant's development in the first year of life. The American Academy of Pediatrics (3) and national guidelines (4) recommend no electronic media use in children under 18 months, other than video-chatting with family members, as children younger than 2 years of age do not benefit from 2D screen media. For children 2–5 years old, a daily amount of less than one hour is advised (3). Yet, in Europe, approximately one third of 2–10-year-old children fail to meet current recommendations (5).

Media exposure can affect child development directly (e.g., consumption of violent media content) or indirectly (e.g., displacement of time) (6). Sleep is paramount for child development (7, 8), and evidence shows that increased daily screen time is associated with shorter sleep per night (9, 10). The displacement of sleeping (9) and physical activity (11), and especially for infants, playing and interacting with their parents or other family members (12) can have multiple negative consequences (11, 13–15).

While parental media use has been proven to be a pivotal predictor for child media use (2, 16), other risk factors must be considered, including child sex, age, hyperactive and sedentary behavior, as well as parental age, BMI, and education. Availability of digital technology in the household, family size and income have also been associated with the amount of electronic media consumption (17).

In the light of this data, it is crucial to collect information on the actual digital media exposure of today's young children. Therefore, analyzing data from a birth cohort, we examined the amount of digital media use in 12-month-old German infants and we determined factors predicting individual screen time.

The purpose of this study was to report baseline data of young children's digital media use and explore potential risk factors for exposure. Contrary to AAP and national guidelines' recommendations, about half the children have already been exposed to digital media during the first year of their life. While most infants did not have regular screen time, there was a subset of 10% of the study population who had a regular exposure for up to half an h on an average weekday. The usual first contact to digital media occurred at the age of 7–9 months. In addition, the presence of a sibling, less personal living space, and increased family TV time were found to be significant predictors of child screen time.

For the examined age group in our present study, to best of our knowledge, hitherto no data exist. However, previous studies on media consumption in older children reported a higher exposure. For example, the 2017 Common Sense Media survey showed that among American children under 2 years of age, 71% had been exposed at least once to TV, 45% to DVD/video, and 46% to mobile devices (20). In Singapore, 24% of infants up to 6-months-old had TV screen time, rising to 61% of 7–24-month-old infants. When viewing the screen time of TV, computer, and mobile devices together, one third of 6-month-old infants had screen time opposed to two thirds of the older infants (21). Together with our data, this might illustrate a trend of increased child screen time with age, as already corroborated by Duch et al. in their review (22).

Not only are children using digital media devices at an earlier age (22), but they are also exposed to a multitude of new interactive media devices (3). Nearly twenty years ago, Vandewater et al. published results showing 0–3-year-olds having an average screen time of nearly 2 hours per day, including TV, videos/DVDs, computers and video games (23). In 2007, Zimmerman et al. only considered TV and DVD/video viewing time at 2 years of age for American children (24). When looking at the German population, the ULM Spatz birth cohort reported 58% of three-year-old children watching TV/DVDs as well as using smartphones up to 1h/day and 14% for more than 1h (screen time data gathered from 2014–2016) (25). Yet, these studies do not name or differentiate between the different types of electronic media available today.

In turn, the Common Sense Media survey divided digital media use by content. The report stated that 0–2-year-olds spent on average, 40 min of TV/DVD/video time (including videos watched on mobile devices), 21 min reading/being read to and 0 min playing games on mobile devices. Also, although average child digital media time remained about the same between 2011 and 2017, a shift toward new mobile devices became apparent (20). Our data, showing initiation of digital media use primarily with TV and smartphone, could be an indicator of a similar trend beginning among infants in Germany.

Adding to evidence, we show that family TV screen time, living space per person, and being second-born are significant predictors of infant screen time. In 2015, Kabali et al. noted that 97 % of children (0.5–4 years old) from low-income minority families in the US had ever used a mobile device and most watched TV daily regardless of age (1). This is consistent with findings of the Common Sense Media report, showing that children from lower income households had substantially more screen time per day (3:29 h vs. 1:50 h, age group 0–8 years). Lower education and ethnic minority (African American > Hispanic > White) were also associated with significantly more child media time. Similarly, a systematic review by Duch et al. showed positive associations between screen time and child's age, BMI, and family belonging to a minority population in children between 0 and 36 months of age (22). Tandon et al. found that children of families with low socioeconomic status had more electronic media devices in the bedroom and more screen time than families with higher socioeconomic status (26). In our multivariate analysis of influencing factors for mean screen time of the infant, we saw a tendency for the maternal subjective social status (MacArthur Scale) to be a protective factor (OR 0.853, p = 0.058). Among other factors with a clear association to socioeconomic status, we found the family's living space to have a strong association with the infant's screen time (OR 0.567, p = 0.007).

In our study, a further influencing factor with a significant association to infant's screen time was the family TV time (OR 1.631, p = 0.027). Interestingly, Jago et al. showed that maternal TV viewing was a stronger predictor of child TV viewing than paternal TV viewing for all age (<7 and >7 years) and gender subgroups (16). It should be noted that these associations are made from cross-sectional data, therefore the direction of the relationship between infant and family media ecology as well as sociodemographic characteristics remains to be investigated.

For young infants, the displacement of activities such as sleep and play by screen media may be particularly harmful toward their behavioral, physical, and cognitive development, not to mention their communication abilities (12). A study by Twenge et al. examined screen time and sleep duration in children from 0–17 years. Their findings showed that both portable and non-portable electronic devices influenced sleep duration for children under age 10 (once over the age of 10, only portable devices had an effect on sleep) (27). This supports the assumption that screen time displaces valuable childhood activities. As numerous studies show, reading or being read to by parents can be supportive in language development (both maternal and foreign language abilities) (28), socio-emotional development (29) and even obesity (30) in young children. Promoting adult-child reading time may be an important protective measure against excessive screen time and stimulate positive child development.

It is important to consider the limitations of our study. First, the study design as a birth cohort with above mentioned exclusion criteria caused a selection bias. Participants are predominantly of German nationality and must be proficient German speakers. In addition, average subjective social status as a proxy for socioeconomic status is relatively high. Second, social desirability bias might play a role when parents state the family's and child's media exposure. Radesky et al. showed that 1/3 of parents underestimated and 1/3 of parents overestimated their child's amount of media use, when comparing online questionnaire to passively measured screen time via an app (31), an observation which indicates that over- and underestimation might be in a balance. Future research will provide more reliable data by directly measuring the time spent with electronic media devices in the homes. Third, in our case of 1-year-old children, child media exposure might simply be passive or background media, if for example infants are with parents while they themselves are using digital media. Still, we did not determine content or motivation of child media use at this young age and can only speculate. Lastly, as a cross-sectional study, the causal direction of the relationship between associated factors and screen time cannot be determined.

In conclusion, our study provides support that excessive family TV time is a major predictor of infant screen time. Moreover, we found smaller living spaces and having one sibling to be significant risk factors. At the age of 12 months, a proportion of 10% of the study population was already regularly exposed to digital media up to half an hour per day. Prospective studies should investigate the effect of passive media exposure, such as background TV. In addition, because child development changes rapidly in the first years, it is crucial to examine younger children and smaller age groups. We suggest that pediatric recommendations should be re-evaluated in the light of the actual exposure to digital media already in infancy and parents should be proactively counseled regarding possible effects on child development.

The members of the KUNO Kids study group are: Andreas Ambrosch (Institute of Laboratory Medicine, Microbiology and Hygiene, Barmherzige Brüder Hospital, Regensburg, Germany); Petra Arndt (ZNL Transfercenter of Neuroscience and Learning, University of Ulm, Ulm, Germany); Andrea Baessler (Department of Internal Medicine II, Regensburg University Medical Center, Regensburg, Germany); Mark Berneburg (Department of Dermatology, University Medical Centre Regensburg, Regensburg, Germany); Stephan Böse-O'Reilly (University Children's Hospital Regensburg (KUNO), Hospital St. Hedwig of the Order of St. John, Regensburg, Germany); Romuald Brunner (Clinic of Child and Adolescent Psychiatry, Psychosomatics and Psychotherapy, Bezirksklinikum Regensburg (medbo), Regensburg, Germany); Wolfgang Buchalla (Department of Conservative Dentistry and Periodontology, University Hospital Regensburg, University of Regensburg, Regensburg, Germany); Sara Fill Malfertheiner, Sebastian Häusler (Clinic of Obstetrics and Gynecology St. Hedwig, University of Regensburg, Regensburg, Germany); André Franke (Institute of Clinical Molecular Biology, Christian-Albrechts-University of Kiel, Kiel, Germany); Iris Heid (Department of Genetic Epidemiology, University of Regensburg, Regensburg, Germany); Caroline Herr (Bavarian Health and Food Safety Authority (LGL), Munich, Germany); Wolfgang Högler (Department of Pediatrics and Adolescent Medicine, Johannes Kepler University Linz, Linz, Austria); Sebastian Kerzel (Division of Pediatric Pneumology and Allergy, University Children's Hospital Regensburg (KUNO), Hospital St. Hedwig of the Order of St. John, Regensburg, Germany); Michael Koller (Center for Clinical Studies, University Hospital Regensburg, Regensburg, Germany); Michael Leitzmann (Department of Epidemiology and Preventive Medicine, University of Regensburg, Regensburg, Germany); David Rothfuß (City of Regensburg, Coordinating Center for Early Interventions, Regensburg, Germany); Wolfgang Rösch (Department of Pediatric Urology, University Medical Center, Regensburg, Germany); Bianca Schaub (Pediatric Allergology, Department of Pediatrics, Dr. von Hauner Children's Hospital, University Hospital, LMU Munich, Munich, Germany); Bernhard H.F. Weber (Institute of Human Genetics, University of Regensburg, Regensburg, Germany); Stephan Weidinger (Department of Dermatology, Venereology and Allergy, University Hospital Schleswig-Holstein, Kiel, Germany); Sven Wellmann (Division of Neonatology, University Children's Hospital Regensburg (KUNO), Hospital St. Hedwig of the Order of St. John, Regensburg, Germany).

The raw data supporting the conclusions of this article will be made available by the authors, without undue reservation.

The studies involving human participants were reviewed and approved by Ethics Committee of the University Regensburg. Written informed consent to participate in this study was provided by the participants' legal guardian/next of kin.

KD wrote the manuscript and designed the tables. DW was responsible for the recruitment of study participants, data collection, and validation. SB performed the statistical analyses. BS-G, CA, MM, and MK contributed to the design of the study, the interpretation of the results, and the authoring of the manuscript. SK developed the study question and design, supervised the data analysis, participated in writing the manuscript, and created the figures. All authors contributed to the article and approved the submitted version.

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

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