Table 5 Relative contribution of changes in the gestational age distribution and in gestational age-specific small-for-gestational age (SGA) rates to temporal changes in sga rates among singleton live births to smokers in the United States (1990–1992 vs. 2002–2004; 2002–2004 vs. 2008–2010)
Period | Gestational Age (weeks) | Modified Kitagawa decomposition (per 10,000 fetuses-at-risk) | ||||
|---|---|---|---|---|---|---|
Contribution of changes in | Total change | Relative contribution of changes in | ||||
Gestational age | Gestational age-specific SGA | Â | Gestational age (%) | Gestational age-specific SGA (%) | ||
1990–1992 vs. 2002–2004 | 24–33 weeks | 0.00 | 5.71 | 5.71 | −0.1 | 100.1 |
34–36 weeks | −0.90 | 22.55 | 21.66 | −4.1 | 104.1 | |
37–38 weeks | −20.04 | 126.93 | 106.89 | −18.8 | 118.8 | |
39–40 weeks | −300.73 | 65.70 | −235.02 | 128.0 | −28.0 | |
41 weeks | −61.97 | −0.14 | −62.11 | 99.8 | 0.2 | |
≥42 weeks | −31.95 | −0.20 | −32.15 | 99.4 | 0.6 | |
Total | −415.59 | 220.57 | −195.02 | 213.1 | −113.1 | |
2002–2004 vs. 2008–2010 | 24–33 weeks | 0.02 | 1.22 | 1.24 | 1.6 | 98.4 |
34–36 weeks | 0.22 | −1.07 | −0.86 | −25.3 | 125.3 | |
37–38 weeks | 0.25 | 41.99 | 42.25 | 0.6 | 99.4 | |
39–40 weeks | −77.13 | 77.82 | 0.68 | −11290.7 | 11390.7 | |
41 weeks | −20.00 | 1.46 | −18.54 | 107.9 | −7.9 | |
≥42 weeks | −4.01 | 0.12 | −3.89 | 103.2 | −3.2 | |
Total | −100.67 | 121.54 | 20.88 | −482.2 | 582.2 | |