Table 3. Associations Between Preterm Birth and Mean Difference in Percentile Rank Change for Individuals Born in Canada, 1990-1996.
| Category | Unmatched cohortsa | Matched cohortsb | ||
|---|---|---|---|---|
| Mean percentile rank change (95% CI) | Mean difference in percentile rank change (95% CI) | Mean percentile rank change (95% CI) | Mean difference in percentile rank change (95% CI) | |
| Preterm (<37 wk) | −0.07 (−0.30 to 0.17) | 1.07 (0.83 to 1.31) | −0.96 (−1.22 to −0.70) | −1.24 (−1.54 to −0.94) |
| Early and full term (37-41 wk) | −1.14 (−1.20 to −1.07) | [Reference] | 0.28 (0.20 to 0.36) | [Reference] |
| Gestational age category, wk | ||||
| 34-36 | 0.41 (0.13 to 0.69) | 1.55 (1.27 to 1.83) | −0.53 (−0.82 to −0.23) | −0.71 (−1.04 to −0.38) |
| 32-33 | −0.73 (−1.42 to −0.04) | 0.40 (−0.29 to 1.10) | −1.67 (−2.48 to −0.87) | −1.98 (−2.87 to −1.09) |
| 28-31 | −1.91 (−2.74 to −1.08) | −0.77 (−1.61 to 0.06) | −3.17 (−4.14 to −2.20) | −3.83 (−4.92 to −2.74) |
| 24-27 | −7.24 (−8.66 to −5.82) | −6.1 (−7.52 to −4.68) | −6.80 (−8.45 to −5.15) | −8.65 (−10.46 to −6.83) |
a
For 1 614 150 individuals.
b
For 968 550 individuals with gestational age less than 37 weeks category; for 897 970 individuals with gestational age 34 to 36 weeks; for 315 050 individuals with gestational age 32 to 33 weeks; for 229 770 individuals with gestational age 28 to 31 weeks; and for 103 160 individuals with gestational age 24 to 27 weeks.