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Table 2 Frequencies and adjusted odds ratios for small-for-gestational-age birth by antenatal model of care and psychosocial risk characteristics, British Columbia, April 1, 2008-December 31, 2012

From: Improving birth outcomes for women who are substance using or have mental illness: a Canadian cohort study comparing antenatal midwifery and physician models of care for women of low socioeconomic position

Small-for-gestational-age birth by model of care
  MW n = 3391 GP n = 25,733 OB n = 4742 MW vs. GP MW vs. OB GP vs. OB
n(%) n(%) n(%) aOR (95% CI) aOR (95% CI) aOR (95% CI)
Mental illnessa
 Yes 42/1011 (4.15) 340/4912 (6.92) 45/545 (8.26) 0.64 (0.46–0.89) 0.49 (0.32–0.77) 0.77 (0.55–1.08)
 No 129/2380 (5.42) 1461/20,821 (7.02) 361/4197 (8.60) 0.76 (0.63–0.92) 0.63 (0.51–0.78) 0.83 (0.73–0.94)
Substance useb
 Yes 6/152 (3.95) 222/2275 (9.76) 23/182 (12.64) 0.41 (0.18–0.93) 0.31 (0.12–0.78) 0.75 (0.46–1.21)
 No 165/3239 (5.09) 1579/23,458 (6.73) 383/4560 (8.40) 0.75 (0.63–0.89) 0.62 (0.51–0.75) 0.83 (0.73–0.94)
Teen mother
 Yes (14–19 yrs.) 8/117 (6.84) 181/2582 (7.01) 21/205 (10.24) 0.94 (0.45–1.98) 0.56 (0.24–1.34) 0.60 (0.36–0.99)
 No (25–29 yrs.) 55/1159 (4.75) 537/7697 (6.98) 126/1370 (9.20) 0.71 (0.53–0.94) 0.55 (0.39–0.76) 0.78 (0.63–0.96)
Mental illness, substance use
 Both 5 or less /95c 90/927 (9.71) 10/76 (13.16) 0.33 (0.10–1.07) 0.22 (0.06–0.87) 0.68 (0.32–1.43)
 Neither 126/2322 (5.43) 1324/19,424 (6.82) 348/4086 (8.52) 0.78 (0.64–0.94) 0.64 (0.51–0.79) 0.82 (0.72–0.94)
  1. Abbreviations: MW midwife, GP general practitioner, OB obstetrician, OR odds ratio, CI confidence interval
  2. aMental illness included any of the following diagnoses prior to, or during the current pregnancy: anxiety disorder, depression, postpartum depression, bipolar disorder, other/unknown (including schizophrenic, mood, and psychotic disorders). Aside from mild anxiety or depression, a physician would diagnose mental illness
  3. bSubstance use included any indication in the medical record of heroin/opioids, cocaine, methadone, solvents, marijuana or other/unknown drugs used by the mother at any time during pregnancy, as well as prescription or other drug use identified as a risk by the provider
  4. cPercentage suppressed due to small cell size
  5. *Outcomes had statistically significant tests of interaction (p < 0.10) comparing difference of effect across strata (yes vs. no)
  6. Models adjusted for all variables listed except stratifying variables: maternal age, parity, pre-pregnancy BMI, infant sex, smoking status, substance use, mental illness/disorder, and Local Health Area (LHA) socioeconomic rank
  7. Odds ratios based on 2378 births with SGA and 33,866 total births with no missing information for this analysis