Table 3

Risks of being born in categories of birth weight in all births 1986–2012 (ONS data) and all, term and preterm births 2006–2012 (NN4B data)*

Unadjusted yearly OR (95% CI)Adjusted† yearly OR (95% CI)Unadjusted† yearly OR (95% CI) for whole study periodAdjusted† yearly OR (95% CI) for whole study period‡
ONS births 1986–2012
Female
 VLBW1.001.001.000.99
 LBW1.001.001.00 0.96
 HBW 1.01 1.01 1.12 1.10
Male
 VLBW1.001.001.00 0.98
 LBW1.001.001.00 0.96
 HBW 1.01 1.01 1.12 1.08
NN4B 2006–2012
Female, all live, singleton births
 VLBW 0.97 0.96 0.91 0.88 (0.86 to 0.91)
 LBW 0.98 0.98 0.94 0.94
 HBW 1.01 1.01 1.03 1.02
Term (≥37 weeks’ gestation), n=2 172 435
 VLBW0.97 (0.93 to 1.02)0.96 (0.92 to 1.01)0.91 (0.80 to 1.06)0.88 [0.78 to 1.03]
 LBW 0.98 0.98 0.94 0.94
 HBW1.001.011.001.03
Preterm (<37 weeks’ gestation), n=120 665
 VLBW 0.98 0.98 0.94 (0.91 to 0.97) 0.94 (0.91 to 0.97)
 LBW 0.98 0.99 0.94 0.97
 HBW1.03 (0.99 to 1.07)1.03 (0.99 to 1.06)1.09 (0.97 to 1.23)1.09 (0.97 to 1.19)
Male, all live, singleton births
 VLBW 0.97 0.97 0.91 0.91
 LBW 0.98 0.98 0.94 0.94
 HBW 1.01 1.01 1.03 1.03
Male term (≥37 weeks’ gestation) n=2 270 840
 VLBW0.97 (0.93 to 1.02)0.97 (0.92 to 1.02)0.8 (0.8 to 1.06)0.91 (0.78 to 1.06)
 LBW 0.98 0.98 0.94 0.94
 HBW 1.01 1.01 1 1.03
Male preterm (<37 weeks’ gestation), n=144 829
 VLBW 0.98 0.98 0.94 (0.91 to 0.97) 0.94
 LBW 0.98 0.99 0.94 0.97
 HBW1.00 (0.97 to 1.03)1.00 (0.98 to 1.03)1.00 (0.91 to 1.09)1.00 (0.94 to 1.09)

  • *OR CIs not presented when these were ≤0.03 g or less wide; significant results in bold.

  • †Adjusted for maternal age, marital status, area-level deprivation, area-level ethnicity (ONS) and individual ethnicity (NN4B).

  • ‡Birth weight change/OR pooled for whole study period ONS (1986–2012), NN4B (2006–2012).

  • HBW, high birth weight; LBW, low birth weight; NN4B, NHS Numbers for Babies; ONS, Office for National Statistics; VLBW, very low birth weight.