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. 2017 Oct 17;2:101. [Version 1] doi: 10.12688/wellcomeopenres.12783.1

Table 1. Characteristics of the included studies, ordered by gestational age categories and age of participant testing.

Author, Year
(country)
Study design,
total n
GA (n) Control
(n)
Age
assessed
(yrs)
Exclusions Exposure
measurement
Cognitive outcomes * Adjustment
Comparison within term (37-42 weeks)
Espel et al. 2014 18
(USA)
Longitudinal
prospective
study

N = 232
37-41
(232)
- 1 Preterm birth (<37 weeks), Post
term birth (>41 weeks)
GA measured from LMP
And Ultrasound
BSID II assessed by
trained clinicians, no
blinding
Maternal ethnicity
Marital status
Fetal Sex
Obstetric complications
Maternal education
Parity
Socio-economic status
Birth weight percentile
Rose et al. 2013 19
(Chile)
Prospective
cohort from an
RCT

N = 1,562
37-42
(1562)
- 1 Infants born at >42 weeks
gestation, birth weight <3kg
GA based on LMP BSID II performed by
trained psychologists,
blinding not reported
Fetal sex
Socio-economic status
Birthweight
Gyamfi
Bannerman et al.
2014 21
(USA)
Prospective
cohort study

N = 20,093
37-42
(18,242)
4 Parents with mental retardation or
alcohol or drug use
Not reported Full-scale IQ scores from
the Stanford-Binet IQ
Maternal age
Maternal education
Socio-economic status
Smoking
Yang et al. 2009 20
(Belarus)
Prospective
cohort from an
RCT

N = 13,824
37 (469)
38 (2100)
42 (171)
43 (10)
39-41
(11, 074)
6.5 Birth weight <2500g GA from hospital
records, 94% confirmed
by ultrasound
Full-scale IQ from WASI
scores performed by
trained pediatricians
Maternal age
Marital status
Maternal education
Parity
Smoking
Maternal height
Parental occupation
Late preterm vs
term
(34 – 36+6)
Nepomnyaschy
et al. 2011 22
(USA)
Prospective
cohort study

N = 5450
34-36
(400)
37-41
(5050)
2 Mothers <15 yrs, congenital
anomalies, multiple births
GA measured by
maternal estimated LMP
General, BSID II
(converted to a
percentile) mental ability,
Language by trained
interviewer blinded to GA
Maternal ethnicity
Maternal age
Marital status
Fetal sex
Obstetric complications
Maternal Education
Parity
Socio-economic status
Smoking
Romeo et al.
2015 23
(Italy)
Prospective
cohort study

N -= 119
34-36
(71)
37-41
(48)
2 Abnormal cranial Ultrasound,
congenital malformations, SGA
Not reported MDI of BSID II at 2 yrs

Blinding and interviewer
training not reported
Fetal sex
Narberhaus et al.
2007 24
(Spain)
Case Control
study

N = 64
34-36
(11)
37-41
(53)
13-14 Mental or physical disability,
perinatal complications/hypoxic
risk
Not reported General WISC full scale
assessed by the same
psychologist
Matched by:
Maternal ethnicity
Maternal age
Fetal sex
Maternal education
Socio-economic status

*Cognitive Outcomes (details in Supplementary File 4): BSID-II = Bayley Scales of Infant Development (2 nd Edition); MDI = Mental Developmental Index, PDI = Psychomotor Developmental Index, WISC = Wechsler Intelligence Scale for Children, WASI = Wechsler Abbreviated Scale of Intelligence

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