Table 1.
Characteristics of the Study Population.
| Infants (N = 75) | ||
|---|---|---|
| Gestational Age at Birth (weeks) | 38.77 ± 1.48 | |
| Age at MRI Scan (days) | 26.91 ± 12.52 | |
| Age at Behavioral Assessment (months) | 6.09 ± 1.43 | |
| Total Hippocampal Volume (mm3)1 | 2983.89 ± 170.71 | |
| Enrichment2 | 14.47 ± 2.8 | |
| Cognitive Development3 | 103.6 ± 9.36 | |
| Female Infant Sex | 32 (42,7) | |
| Mothers (N = 75) | Age (Years) | |
| Age (Years) | 28.4 ± 6.16 | |
| SES4 | 3.16 ± 0.9 | |
| Highest Maternal Educational Level | ||
| Less than High School | 2 (2.7) | |
| High School | 12 (16) | |
| Vocational Training or Some College without Degree | 35 (46.7) | |
| Associates or Bachelor’s Degree | 19 (25.3) | |
| Advanced Degree (Master’s / Doctorate) | 7 (9.3) | |
| Household Income Last Year (in $) | ||
| Below 15 000 | 7 (9,3) | |
| 15 000–29 999 | 13 (17,3) | |
| 30 000–49 999 | 18 (24) | |
| 50 000–100 000 | 27 (36) | |
| Over 100 000 | 6 (8) | |
| Race/Ethnicity | ||
| Non-Hispanic White | 30 (40) | |
| Non-Hispanic Other | 10 (13.3) | |
| Non-Hispanic Asian | 6 (8) | |
| Hispanic White | 24 (32) | |
| Hispanic Other | 5 (6.6) | |
| Maternal Intellectual Ability5 | 95.35 ± 11.87 | |
| Maternal Sensitivity6 | 10.29 ± 2.9 | |
Values are mean ± SD or n (%).
Adjusted for intracranial volume, gestational age at birth and age at MRI scan.
Combination of access to variety in daily stimulation, provision of appropriate play material and involvement in activities that afford learning assessed by Infant-Toddler Home Observation for Measurement of the Environment (IT-HOME).
Cognitive Scale composite score from the Bayley Scales of Infant and Toddler Development, Third Edition (Bayley-III; Bayley, 2006).
Maternal socioeconomic status (SES) was defined as a combination of maternal educational level (originally assessed in categories from less than high school to advanced degree and then recoded into values from 1 to 5) and household income (originally assessed in categories from $15,000 to $100,000 and then recoded into values from 1 to 5; n = 4 missing values replaced by mean substitution).
Perceptual reasoning subtests of the Wechsler Adult Intelligence Scale-Revised (WAIS; Wechsler, 1955).
Sum score of sensitivity to non-distress, positive regard and intrusiveness based on coders rating of a semi-structured play situation (Jaeger, 1999).