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Table 2 Univariate and multivariate interval regression models for the association between maternal pre-pregnancy Body Mass Index and hospital costs of childbirth (N = 7564)

From: Overweight and obese pre-pregnancy BMI is associated with higher hospital costs of childbirth in England

  Total cost of child birth
Model I Coefficient (95%CI) Model II Coefficient (95%CI) Model III Coefficient (95%CI) Model IV Coefficient (95%CI)
Pre-pregnancy BMI
 Underweight −14.84 (−48.04; 18.34) 0.78 (−32.64; 34.19) −7.85 (− 34.32; 18.61) − 4.09 (− 17.15; 8.97)
 Normal weight Ref. Ref. Ref. Ref.
 Overweight 21.88 (4.46; 39.29)** 23.62 (5.68; 41.57)** 9.79 (−5.11; 25.00) −2.92 (−10.55; 4.70)
 Obese (class I) 81.59 (48.37; 114.80)** 86.01 (53.64; 118.37)** 43.29 (14.39; 72.19)** −0.37 (−12.25; 11.51)
 Obese (class II and III) 126.41 (63.51; 189.31)** 134.13 (72.78; 195.47)** 55.22 (−2.02; 112.46)* −1.64 (− 25.03; 21.74)
Education
 None of these Ref. Ref. Ref.
 GCSE/A level 19.76 (−0.34; 39.87)* 12.94 (−4.37; 30.26) −3.36 (−12.29; 5.57)
 Higher education 41.53 (15.18; 67.89)** 25.55 (3.62; 47.49)** −0.82 (−11.02; 9.38)
Marital Status
 Single 24.89 (7.53; 42.23)** 20.81 (5.28; 36.34)** 1.49 (−6.06; 1.11)
 Couple Ref. Ref. Ref.
Maternal Age 1.32 (−0.28; 2.92) −0.72 (−2.09; 0.65) 0.52 (− 0.08; 1.11)
OECD equivalised income quintile
 1st (lowest) Ref. Ref. Ref.
 2nd 0.81 (−21.95; 23.58) −2.76 (− 23.18; 17.66) −1.71 (−10.85; 7.42)
 3rd 9.48 (−19.06; 38.030 7.90 (−17.77; 33.56) 2.70 (− 5.88; 11.28)
 4th 34.55 (9.24; 59.86)** 19.55 (−1.30; 40.40)* −6.17 (− 17.37; 5.02)
 5th (highest) 56.73 (24.26; 89.21)** 33.96 (4.45; 63.46)** 2.19 (−9.49; 13.87)
Ethnicityb
 White Ref. Ref. Ref.
 Mixed/Other 68.75 (13.33; 124.17)** 45.54 (−3.59; 94.67) 3.17 (−13.35; 19.69)
 Asian 64.51 (31.11; 97.90)** 57.11 (30.49; 83.73)** −0.25 (−18.38; 17.87)
 Black Caribbean or Black African 93.14 (41.99; 144.30)** 69.75 (30.85; 108.65)** 16.68 (1.90; 31.46)**
Government Office Regiona
 North Ref. Ref. Ref.
 Midlands & East 9.33 (−40.88; 59.54) 10.62 (−33.71; 54.96) 8.36 (−9.24; 25.96)
 London   −68.82 (−108.87; −28.77)** −52.61 (−88.24; − 16.97)** −19.16 (− 49.10; 10.79)
 South − 14.49 (− 45.19; 16.22) − 8.76 (− 37.40; 19.88) −0.92 (− 21.41; 19.67)
Premature
 No Ref. Ref.
 Yes    308.40 (268.12; 348.67)** −3.53 (−22.06; 15.01)
Type of delivery
 Spontaneous Ref. Ref.
 Forceps    129.42 (102.86; 155.98)** 5.40 (−5.33; 16.14)
 Caesarean    330.00 (309.58; 350.42)** 10.66 (−1.97; 23.30)*
 Other    156.63 (64.70; 248.57)** 34.12 (21.93; 46.31)**
Parity
 Primiparae Ref. Ref.
 Multiparae    0.01 (−42; 03; 42.04) 9.88 (−1.71; 21.48)
Length of Stay (days) 116 (112.02; 120.22)**
Constant 732.79 (716.10; 749.48) 641.21 (588.35; 694.07) 619.98 (574.80; 665.17) 407.12 (383.82; 430.39)
  1. The coefficients are also marginal effects
  2. Model I: unadjusted
  3. Model II: adjusted for maternal age, education, marital status, ethnicity, equivalised income, and government region
  4. Model III: Model II + number of previous children, number of babies delivered, pre-term birth, and type of delivery
  5. Model IV: Model III + Length of stay
  6. Abbreviations: CI Confidence interval, BMI Body mass index, OECD Organisation for economic co-operation and development
  7. ** p ≤ 0.05; * 0.1 ≥ p > 0.05
  8. aNorth includes: North East, North West, Yorkshire & the Humber, Northern Ireland, and Wales; South Includes: South East and South West; Midland and East include: East Midlands, West Midlands, and East of England
  9. bAsian includes: Indian, Pakistani, and Bangladeshi