A comprehensive search, through the following databases: Ebscohost (Academic search complete, Africa-Wide information, PsychArticles, SocIndex, Cinahl), JStor, Sciencedirect, Springerlink, Pubmed and Sage, was conducted for the period between 2003-2014. After a brief review of available literature which included: knowledge of child development and parenting styles, parent knowledge of child development and parenting styles, maternal knowledge of child development and parenting styles, paternal knowledge of child development and parenting styles, child development knowledge and parenting styles, early childhood development and parenting styles, search terms were constructed and agreed upon by both reviewers. The titles and abstracts were retrieved independently by one researcher (SJS) and then screened by another researcher (NVR) using the same inclusion criteria as below in order to determine eligibility of the studies for inclusion to the review.

The criteria for inclusion into the study were: (i) publication in English language; (ii) publication dates between 2003 and 2014; (iii) target population being parents with children; (iv) association between knowledge of child development and parenting or parenting styles. This systematic review included only quantitative and intervention studies to review the instruments used in these studies and to examine the association between knowledge of child development and parenting.

The initial search was conducted by one researcher (SJS) and the titles and abstracts screened by another reviewer (NVR). The initial search on titles yielded a total 1591 - full text articles and abstract - across all the search terms based on the inclusion criteria agreed upon by the researchers. At this point the methodological approach of the studies was not considered as yet. In other words this total comprises of the total number of hits based on the search terms used. Thereafter the articles were screened for eligibility and a sample of 23 records was attained based on the inclusion criteria. At this point the articles were roughly screened based on whether the study was related to the topic of interest. All duplications (N=3) were then removed from the data and a final sample of 20 studies was retrieved. The citations for the 20 articles were read to establish inclusion into the systematic review. After reviewing the 20 retrieved articles 12 were excluded based on the methodology used in the study as only quantitative and intervention studies formed part of the inclusion criteria. The final inclusion sample consisted of eight articles which were based on the methodological quality of the study.

The data extraction sheet was designed to identify information pertaining to the author, date of publication, country, population (sample size, age, gender), study design, measuring tool used for data collection, definition of knowledge of child development, definition of parenting/parenting styles and results (Table 4).

Of the initial 23 studies only eight studies were included in the review. The reviewers decided that studies scoring 50% and above will be included in the review. Of the eight studies three [21-23] scored below average (50%) for the methodological appraisal. Of the nine questions on the critical appraisal tool which was applied to each study to appraise the quality; these studies only answered four questions hence the below average score. Though the studies fell below the average of 50% it still fell within the category of satisfactory to good. Furthermore these studies were included in the review as they contained valid content information pertaining to the research question.

The studies, in the final sample, were one from Turkey [24], three from Canada [22, 25, 26], one from the United Kingdom [21] and three from the United States of America [23, 27, 28]. Data was collected by means of questionnaires in all of the studies. The sample sizes ranged from 41 participants to 8605 participants. The participants in the studies were parents of children of varying ages with the youngest being under 12 months and the oldest 10 years old. Two of the studies were cross-sectional [21, 25], two were longitudinal studies Hess, Teti & Hussey-Gardner, 2004) and three were intervention studies [24, 26, 28]. The final study was a population study [22].

Four of the eight studies provide a definition relating to either parenting or parenting styles. The study of Oncu and Uluer [24] defines parenting as consisting of a complex of duties and responsibilities in which mother and/or father has to decide how to organize and guide their son/daughter. Two of the studies provide a definition which relates to parenting confidence which is defined as the parents’ perception that they can effectively manage tasks relating to parenting [25, 27]. The study conducted by Arnott and Brown [21] cites Baumrind [29] in defining parenting styles as traditionally conceptualizing parenting behaviours as individual differences along two dimensions: warmth/nurturance and control. Combinations of these elements categorize parenting style typologies. Neither of the studies included in this review provide a clear definition for knowledge of child development but the content explores the issue of parental knowledge or cognitions of which one of the aspects is knowledge of child development [23, 25-27].

Of the eight studies, four studies discuss and explore knowledge of child development [23, 25-27]. In the Hess, Teti and Hussey-Gardner [27] study, participants scored an average of 82.87%, which was considered relatively high. Mothers with higher education and income and who were married had increased knowledge when compared to mothers who had lower education, lower income and were unmarried. Furthermore, mothers who had increased knowledge of child development were more sensitive to their children. The study also found that Caucasian mothers had more knowledge of child development than African American mothers. The Bornstein and Putnick [23] study highlighted that the degree of knowledge varied according to age and found that older mothers were more knowledgeable than younger mothers. However, the difference was not significant. Morawska and Sanders [25] add that having knowledge of factors, which correlate to toddler behaviour may facilitate improved understanding of the factors that are important to develop interventions and programmes. While Morawska and Sanders [25] do not specifically focus on parental knowledge they do investigate confidence, which has been found to be dependent on parental knowledge. The study results show that parents often did not know what to do when children threw tantrums; that their parenting style affects child behaviour and they also did not know about setting limits. A later study conducted by Winter, Morawska and Sanders [26] reports that pre-intervention parents in the higher socio-economic status group were found to have greater knowledge of child development. However, post parenting intervention parental knowledge and confidence was increased in both low and high socio-economic groups. The study further suggests that parents in high socio-economic groups would benefit from opportunities to practice their skills and receive feedback whereas the focus for low socio-economic status parents should be on teaching new skills and strategies to improve knowledge and confidence.

The results of this review found that mothers with higher education, higher income and married were more responsive to their children than less educated, lower income and unmarried mothers. Furthermore, parent confidence was high but naively confident mothers may be at risk for parenting difficulties as their children grow into toddlers [27]. In trying to understand the parenting approaches used in the phase of early childhood development, the studies in this review show that nurturance and control strongly emerged in this phase of development. For example mothers high in nurturance would cuddle their child instead of leaving the child to settle, mothers high on the discipline believed that they had to modify their child’s behaviour and were not particularly swayed by their infants for example believing that crying was used to manipulate them, while mothers high in routine would adhere to sticking to a strict routine for their baby [21]. When these factors are converted into Baumrind’s typology of parenting styles they found that mothers high in routine, discipline and low in nurturance could be considered authoritarian, whereas mothers high in nurturance with intermediate levels of routine and discipline may be viewed as authoritative [21].

Furthermore mothers with high anxiety were more likely to seek advice and guidance from others whereas their counterparts were more likely to progress their child and compared the child to others of the same age. Lastly, parenting style was also associated to maternal age and education [21].

Yet another study [25] concluded that maternal confidence and dysfunctional parenting were interrelated and were also predicted best by parenting variables, in contrast to socio-demographic and child variables. Maternal confidence also mediated the relationships between family income and toddler behaviour. Parenting style and confidence are important modifiable factors to target in parenting interventions.

The last study [22] reported that parental depression and hostile parenting were not found to have significant effects contrary to previous findings. Furthermore, parental depression suggests an impediment to optimal parenting practices but the models included direct measures of parenting and in their presence the effect of depression became non-significant. Therefore, the effects of depression appear to operate through resultant parenting practices. Similarly, hostile parenting has been shown to have a deleterious effect on development and the measure used in these analyses had a significant negative effect but was non-significant in the presence of a measure of positive parenting.

The study by Oncu and Unluer [24] reported that mothers were found to restrict father involvement. Subsequently, both mothers and fathers were found to score high in protective and discipline dimensions with fathers scoring higher in these dimensions and being more protective. Similarly, Winsler, Madigan and Aquilano [28] reported that fathers perceived their spouses to be more authoritative followed by permissive whereas mothers perceived their spouses as more authoritative. It was further found that parents who share similar parenting styles were able to report accurately on their spouses parenting styles. The study concluded that corresponding parenting styles in the same home were important.

The study of Winsler, Madigan and Auilano [28] investigated the differences between maternal and paternal parenting style and found that there was a variance in parenting styles and little agreement between two parents in the same house with a pre-school aged child. The fathers reported that they perceived their spouses to be more authoritative or permissive whereas they perceived themselves to be more authoritarian. Furthermore the study states that it may be that parents perceived that there were greater differences between each others’ styles than indicated by self-reported parenting style due to (a) parents’ beliefs that traditional parenting stereotypes reflect effective parenting practices and (b) that self-reported parenting style in turn reflects those beliefs. This might suggest that parents’ perceptions of others’ parenting style is a more accurate indicator of true parenting behaviours compared to self-reported parenting style, and is thus an important question for future researchers. This study however did not explore knowledge of child development in relation to parenting but it explored differences between paternal and maternal parenting styles.

Another study, Oncu & Unleur [24], investigated whether parental attitudes changed after parental education. The results of the study found that parenting education, which increases knowledge, had a positive effect on positive parenting, pressure and discipline dimensions and found that fathers scored higher in protective parenting than the mothers. However this study was conducted with 26 parents and the limitation included that topics discussed on healthy child development were limited, the change effect was small and father participation was not consistent or equal. Three of the studies reviewed [25, 26] found that maternal confidence and dysfunctional parenting were interrelated and that knowledge of child development was a moderating factor. Winter, Morawska and Sanders [26] found that the effect for confidence was larger than that for knowledge of child development. Two of the studies included in the review [21] [23] concluded that maternal age and education were a pervasive factor in cognition and parenting. However the correlation between parenting and maternal age and cognition was higher for younger mothers as opposed to older mothers [23]. The study of Pevalin, Wade & Brannigan [22] did not directly investigate knowledge of child development but concludes that dysfunctional and hostile parenting has a negative effect on early child development. The findings suggest that maternal education, positive parenting and social support may counter the negative effect on the child’s development process.

All the studies reported on the measuring instruments that were used include what the instrument is designed to measure. Two studies used the Knowledge of Infant Development inventory (KIDI) to assess mothers’ knowledge of child development, parental practices, health and safety and norms [23, 27]. However Hess, Teti and Hussey-Gardner [27] used only a portion of the KIDI namely the parenting subscale to measure knowledge against parenting. Of the eight studies conducted [21-28] several parenting questionnaires were used to measure parental competence, behaviour and style of which three studies used the Parenting Style Dimension Questionnaire (PSDQ) to determine the participant’s parenting style category [21, 23, 28]. Another two studies use the Eyberg Child Behavior Inventory (ECBI), which measures parental perception of children’s problematic behaviour. Four studies [21, 22, 24, 28] used a single instrument while the remaining four used more than one instrument [23, 25-27]. However regardless of which instrument was used the measures reported to have adequate to high internal consistency.