TABLE 2.
Frequency and Risk of Major BDs by Infant Characteristics
| Characteristica | N | Infants With a BD, n (%) | Adjusted RR for BDs (95% CI)b | P b |
|---|---|---|---|---|
| Maternal age, y | <.001 | |||
| 40+ | 1263 | 99 (7.8) | 1.70 (1.40–2.08) | — |
| 35–39 | 4546 | 259 (5.7) | 1.25 (1.09–1.44) | — |
| 30–34 | 7887 | 326 (4.1) | 0.94 (0.82–1.07) | — |
| 25–29 | 8677 | 407 (4.7) | 1.03 (0.92–1.17) | — |
| <25 | 14 869 | 685 (4.6) | 1.0 | — |
| Multiple birth | <.001 | |||
| Yes | 9573 | 328 (3.4) | 0.66 (0.59–0.75) | — |
| No | 27 688 | 1448 (5.2) | 1.0 | — |
| BW, g | <.001 | |||
| 401–500 | 1556 | 59 (3.8) | 0.66 (0.50–0.86) | — |
| 501–750 | 7970 | 266 (3.3) | 0.61 (0.53–0.71) | — |
| 751–1000 | 8546 | 422 (4.9) | 0.91 (0.80–1.03) | — |
| 1001–1250 | 8985 | 467 (5.2) | 0.97 (0.86–1.09) | — |
| 1251–1500 | 10 205 | 562 (5.5) | 1.0 | — |
| GA, wk | <.001 | |||
| <25 | 6428 | 168 (2.6) | 0.36 (0.29–0.45) | — |
| 25–28 | 15 531 | 583 (3.8) | 0.55 (0.46–0.65) | — |
| 29–32 | 13 158 | 740 (5.6) | 0.72 (0.62–0.83) | — |
| 33+ | 2135 | 284 (13.3) | 1.0 | — |
| SGA | <.001 | |||
| Yes | 7731 | 702 (9.1) | 1.80 (1.59–2.03) | — |
| No | 29 521 | 1073 (3.6) | 1.0 | — |
| Boy | .01 | |||
| Yes | 18 934 | 842 (4.4) | 0.89 (0.81–0.97) | — |
| No | 18 324 | 932 (5.1) | 1.0 | — |
| Race/ethnicity | <.001 | |||
| Non-Hispanic black | 14 249 | 534 (3.7) | 0.68 (0.60–0.78) | — |
| Hispanic | 6317 | 367 (5.8) | 1.07 (0.92–1.23) | — |
| Other | 1630 | 77 (4.7) | 0.86 (0.67–1.09) | — |
| Non-Hispanic white | 14 962 | 787 (5.3) | 1.0 | — |
Information was missing for maternal age: 20 infants; multiple birth: 1; GA: 10; SGA: 10; gender: 4; race: 104.
RRs, CIs, and P values by the Score χ2 test from a modified Poisson regression model that included study center, maternal age (categories shown), GA (categories shown), SGA, gender, race (categories shown), multiple birth, cesarean delivery, antenatal steroids, and outborn status. GA and SGA were replaced with BW (categories shown) for estimation of RRs associated with BW. The Score test provides an overall test of association between the characteristic and risk of birth defects. For characteristics with two levels (eg, multiple birth), the P value corresponds to statistical significance for the RR shown. Dashes visually define the rows. For characteristics categorized as more than two levels, dashes are shown to indicate that P values for the pairwise comparisons represented by the relative risks are not shown. Statistically significant RRs are indicated by confidence intervals that do not include 1.0.