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Table 3 Gestational Age-Specific Rates of Fetal Growth Restriction Based on a Sex-Specific Standard [38] and Differences in Growth Restriction, Stillbirth and Early Neonatal Mortality Among Males and Females, Singleton Births, United States, 1997 and 1998.

From: Customized birth weight for gestational age standards: Perinatal mortality patterns are consistent with separate standards for males and females but not for blacks and whites

Gestational age Fetal growth restriction Stillbirth rate ratio(males vs females) Early neonatal mortality rate ratio(males vs females)
  Males Females Rate ratio (males vs females)   
  Number Rate † Number Rate †    
28 631 0.2 502 0.1 1.20 1.01 1.36
29 764 0.2 660 0.2 1.10 1.04 1.33
30 1,165 0.3 923 0.3 1.20 1.10 1.23
31 1,539 0.4 1,369 0.4 1.07 1.10 1.15
32 2,141 0.6 1,866 0.5 1.09 1.22 1.02
33 3,294 0.9 2,946 0.9 1.07 1.15 1.08
34 5,691 1.6 5,098 1.5 1.07 1.13 1.29
35 8,934 2.5 7,922 2.3 1.08 1.10 1.38
36 15,813 4.6 13,910 4.2 1.09 1.13 1.19
37 30,029 9.1 25,180 7.9 1.15 1.19 1.13
38 55,401 18.5 49,599 17.1 1.09 1.07 1.27
39 84,257 35.7 79,440 33.9 1.05 1.04 1.28
40 75,983 52.8 74,504 51.1 1.03 0.98 1.16
41 36,956 62.6 34,214 56.5 1.11 0.95 1.10
≥42 14,679 100.5 14,551 96.7 1.04 1.05 1.19
Total‡ 337,277 91.6 312,684 89.3 1.03 1.08 1.27
  1. † Gestational age-specific growth restriction rates (based on a sex-specific standard [38]) were calculated by dividing the number of small-for-gestational age live births (<10th percentile) at any gestational age by the number of fetuses at risk at that gestation. Stillbirth and early neonatal mortality rates were also calculated using fetuses at risk as the denominator.
  2. ‡ All gestational ages ≥22 weeks, except for growth restriction indices which were based on live births between 28 and 42 weeks.