Table 3.
Association between short and long IPI and child outcomes
| Unadjusted | Minimally adjusted | Fully adjusted | |
|---|---|---|---|
|
| |||
| Birth outcomes | |||
|
| |||
| b (95% CI) | b (95% CI) | b (95% CI) | |
|
| |||
| Birth weight (grams) | |||
| Short IPI | −139.12 (−212.85,−65.39) | −140.88 (−213.51,−68.24) | −89.15 (−158,96,−19.35) |
| Long IPI | −82.85 (−147.48,−18.22) | −87.08 (−151.03,−23.14) | −38.60 (−104.26,27.07) |
| Birth weight (grams) adjusted for gestational age | |||
| Short IPI | −137.91(−210.94,−64.89) | −126.31 (−190.48,62.14) | −73.94 (−135.16,−12.71) |
| Long IPI | −84.89 (−147.49,−20.29) | −62.34 (−118.95,−5.73) | −34.09 (−92.71,24.54) |
| Gestational age (weeks) | |||
| Short IPI | −0.09 (−0.33,0.15) | −0.09 (−0.33,0.15) | −0.10 (−0.34,0.13) |
| Long IPI | −0.18 (−0.36,0.00) | −0.18 (−0.37,0.00) | −0.04(−0.23,0.16) |
|
| |||
| OR (95% CI) | OR (95% CI) | OR (95% CI) | |
|
| |||
| Preterm birth | |||
| Short IPI | 1.32 (0.91,1.90) | 1.33 (0.92,1.94) | 1.29 (0.89,1.88) |
| Long IPI | 1.21 (0.88,1.66) | 1.22 (0.88,1.68) | 1.04 (0.74,1.47) |
|
| |||
| Infant temperament (for all measures M=0 and SD =1) | |||
|
| |||
| b (95% CI) | b (95% CI) | b (95% CI) | |
|
| |||
| Infant activity level | |||
| Short IPI | −0.02 (−0.26,0.23) | −0.02 (−0.26,0.23) | −0.11 (−0.35,0.14) |
| Long IPI | −0.14 (−0.32,0.04) | −0.14 (−0.33,0.04) | −0.21 (−0.39,−0.02) |
| Infant predictability | |||
| Short IPI | 0.01 (−0.21,0.22) | 0.02 (−0.20,0.23) | 0.07 (−0.14,0.28) |
| Long IPI | −0.04 (−0.19,0.12) | −0.04(−0.19,0.12) | 0.03 (−0.13,0.20) |
| Infant fearfulness | |||
| Short IPI | 0.07 (−0.09,0.24) | 0.06 (−0.11,0.23) | −0.01 (−0.17,0.16) |
| Long IPI | −0.04 (−0.15,0.07) | −0.04 (−0.15,0.07) | −0.09 (−0.22,0.03) |
| Infant positive affect | |||
| Short IPI | −0.01 (−0.16,0.17) | 0.01 (−0.16,0.17) | 0.02 (−0.15,0.18) |
| Long IPI | 0.07 (−0.05,0.02) | 0.07 (−0.05,0.18) | 0.06 (−0.06,0.19) |
| Infant fussiness | |||
| Short IPI | 0.17 (0.01,0.32) | 0.17 (0.01,0.33) | 0.08 (−0.08,0.23) |
| Long IPI | 0.03 (−0.08,0.14) | 0.03 (−0.08,0.14) | −0.04 (−0.16,0.08) |
|
| |||
| Cognitive ability (for all measures M=0 and SD =1) | |||
|
| |||
| b (95% CI) | b (95% CI) | b (95% CI) | |
|
| |||
| Digit span | |||
| Short IPI | −0.09 (−0.23,0.04) | −0.09 (−0.22,0.04) | 0.01 (−0.12,0.14) |
| Long IPI | −0.13 (−0.24,−0.01) | −0.12 (−0.24,−0.00) | −0.04 (−0.16,0.08) |
| PPVT | |||
| Short IPI | −0.23 (−0.35,−0.11) | −0.20 (−0.32,−0.08) | −0.01 (−0.11,0.09) |
| Long IPI | −0.09 (−0.20,0.02) | −0.08 (−1.19,0.03) | 0.03 (−0.08,0.14) |
| Math | |||
| Short IPI | −0.26 (−0.40,−0.12) | −0.25 (−0.39,−0.11) | −0.04 (−0.16,0.08) |
| Long IPI | −0.15 (−0.27,−0.04) | −0.15 (−0.26,−0.04) | −0.06 (−0.17,0.05) |
| Reading recognition | |||
| Short IPI | −0.20 (−0.32,−0.07) | −0.19 (−0.32,−0.06) | −0.03 (−0.14,0.09) |
| Long IPI | −0.10 (−0.21,0.01) | −0.09 (−0.20,0.03) | 0.04 (−0.08,0.15) |
| Reading | |||
| Short IPI | −0.19 (−0.32,−0.6) | −0.17 (−0.30,−0.05) | −0.00 (−0.12,0.11) |
| Long IPI | −0.11(−0.22,−0.01) | −0.10 (−0.21,0.01) | 0.05 (−0.06,0.15) |
|
| |||
| Externalizing problems (for all measures M=0 and SD =1) | |||
|
| |||
| b (95% CI) | b (95% CI) | b (95% CI) | |
|
| |||
| Conduct | |||
| Short IPI | 0.04 (−0.07,0.16) | 0.05 (−0.07,0.16) | −0.02 (−0.13,0.09) |
| Long IPI | 0.00 (−0.11,0.11) | −0.01 (−0.11,0.10) | −0.07 (−0.18,0.05) |
| Oppositional defiant | |||
| Short IPI | 0.00 (−0.13,0.13) | 0.02 (−0.11,0.15) | −0.05 (−0.17,0.07) |
| Long IPI | −0.03 (−0.14,0.08) | −0.02 (−0.13,0.08) | −0.05 (−0.15,0.06) |
| Attention-Deficit/Hyperactivity | |||
| Short IPI | 0.01 (−0.12,0.14) | 0.03 (−0.09,0.16) | −0.08 (−0.20,0.04) |
| Long IPI | 0.05 (−0.05,0.16) | 0.05(−0.05,0.16) | 0.02 (−0.08,0.13) |
Note: IPI = interpregnancy interval. Short IPI defined as 1 year or less. Long IPI defined as more than 3 years. Reference IPI was 1 to 3 years. b=estimated beta weight. OR = odds ratio. CI=confidence interval. The unadjusted models did not control for any covariates. The minimally adjusted models controlled for child sex and birth order. The fully adjusted models controlled for child sex and birth order; maternal race/ethnicity, age at childbearing, education, IQ, depression, alcohol use and dependence symptoms, and delinquency; family income; whether families included half-siblings; and whether a miscarriage, stillbirth, or abortion occurred within the focal child’s IPI.