Table 1. Main characteristics of included studies.
| Studies* | Implementation year | Country | Case | Outcome | Control | Outcome | Method to confirm infection | ID diagnostic criterion |
|---|---|---|---|---|---|---|---|---|
| Camp et al. (1998) [27]# | 1959–1965 | USA | 5244 | 244 | 30476 | 1068 | Microbial culture | WISC |
| Mcdermoot et al. (2000) [28]# | 1995–1998 | USA | 8578 | 673 | 32237 | 2205 | ICD-9 codes | ICD-9 codes |
| Zhang et al. (2007) [29] # | 1997–2000 | China | 49 | 4 | 50 | 1 | ELISA | WISC |
| Mann et al. (2009) [17]֍ | 1996–2002 | USA | 5388 | 1366 | 129208 | 27961 | ICD-9 codes | ICD-9 codes |
| Bilder et al. (2013) [16] ֍ | 1994–2001 | USA | 146 | 3 | 16936 | 47 | ICD-9 codes | ICD-9 codes |
| Lee et al. (2015) [26] ֍ | 1984–2011 | Sweden | 2280 | 124 | 471056 | 16352 | ICD-9, and ICD-10 codes | ICD-9, and ICD-10 codes |
| McCarter et al. (2020) [30]֍ | 2004–2013 | USA | 4781 | 154 | 119266 | 2774 | ICD-9 codes | ICD-9 codes |
| Brynge et al. (2022) [15]# | 1987–2016 | Sweden | 34013 | 445 | 515954 | 5087 | ICD-8, ICD-9, and ICD-10 codes | ICD-9 codes |
* All studies had retrospective cohort design and were classified as high-quality studies based on Newcastle-Ottawa Scale.
#Infection-based studies; these studies evaluated prevalence or incidence of ID in follow-up of children with- and without- exposure to maternal infection.
֍Intellectual disability-based studies; these studies recruited children affected by ID as cases and healthy children as controls and assessed maternal infection in these subjects retrospectively.
Abbreviation; WISC, Wechsler Intelligence Scale for Children; ICD, International Classification of Diseases.