2. Materials and Methods
Using the “Preferred Reporting Items for Systematic Reviews and
Meta-Analyses” (PRISMA) 2009 guidelines, a comprehensive search
independently using two databases, namely OVID/Medline and PubMed, was
performed for the keywords: “sexual dimorphism”, “sex differences “,
“gender difference”, ”brain”, “infants”, and “neonates”.
Keywords were combined using the Boolean operators OR and AND. The
search strategy was as follows: (“sexual dimorphism” OR “sex
differences” OR “gender differences”) AND (brain) and (“infants” OR
“neonates”). All the keywords were used as exploded medical subject
headings (MeSH) for the OVID/Medline and Pubmed. This study addressed
studies published in peer-reviewed journals from 1945 p to 31 October
2022. All duplicates were excluded in addition to abstracts, case
reports, non-English articles, reviews, commentaries, and editorials.
All English studies published in any year about sexual differences in
neonates’ and infants’ brains were included. Bibliography lists from all
eligible articles were also hand-searched to identify additional papers
potentially relevant for inclusion.
No date restrictions had been set
for the articles to be retrieved from the search. A total of 568 records
were found in the literature related to brain sex differences. Of these,
208 studies did not meet our eligibility criteria and were excluded.
Finally, a total of 36 full-text studies were included in our systematic
review (Figure 1).