Wood S, Tang. Changes in Rates of cesarean delivery in primiparous women in labor in a Canadian population, 1992–-2018. Obstet Gynecol 2021;137.
The authors provided this information as a supplement to their article.
©2021 American College of Obstetricians and Gynecologists. Page 1 of 3
Appendix 1. Average Birth Weight and Frequency of Birth Weight ≥4000gm and ≥4500 Grams by Year of Birth Categories
Year of Birth Birth weight, mean (SD) ≥4000gm n (%) ≥4500gm n (%)
1992-1998 3374 gm (484) 8116 (9.5) 1102 (1.3)
1999-2003 3412 gm (483) 7572 (11.1) 1060 (1.5)
2004-2008 3389 gm (483) 8385 (10.0) 1152 (1.4)
2009-2013 3359 gm (474) 8206 (8.7) 1016 (1.1)
2014-2018 3325 gm (467) 6977 (7.4) 800 (0.9)
Nulliparous women in labor, singleton pregnancies, vertex presentation Alberta 1992-2018.
Wood S, Tang. Changes in Rates of cesarean delivery in primiparous women in labor in a Canadian population, 1992–-2018. Obstet Gynecol 2021;137.
The authors provided this information as a supplement to their article.
©2021 American College of Obstetricians and Gynecologists. Page 2 of 3
Appendix 2. Odds Ratios (adjusted) and 95% Confidence Intervals for Associations Between Maternal Risk Factors and Cesarean Delivery by Time Period
1992-1998 1999-2003 2004-2008 2009-2013 2014-2018 Maternal Risk
Factors Maternal
weight >91kg 2.48 (2.23,
2.76) 2.13 (2.00,
2.26) 1.87 (1.77,
1.98) 1.85 (1.76,
1.94) 1.63 (1.55, 1.71) Gestational
Diabetes 1.48 (1.24,
1.78) 1.57 (1.41,
1.75) 1.63 (1.50,
1.77) 1.45 (1.36,
1.55) 1.31 (1.24, 1.39) Smoking
during pregnancy
0.89 (0.83,
0.97) 0.86 (0.81,
0.90) 0.93 (0.89,
0.97) 0.96 (0.92,
1.00) 0.98 (0.93, 1.03) Pregnancy
Induced Hypertension
1.81 (1.60,
2.05) 1.68 (1.57,
1.80) 1.72 (1.63,
1.83) 1.61 (1.52,
1.70) 1.56 (1.48, 1.65) Antepartum
Risk Score ≥7 1.52 (1.20,
1.92) 1.24 (1.07,
1.43) 1.26 (1.22,
1.41) 1.09 (0.98,
1.21) 1.32 (1.21, 1.45) Maternal
age≥35 years 2.26 (2.10,
2.44) 2.13 (2.00,
2.27) 1.95 (1.85,
2.06) 1.87 (1.78,
1.97) 1.74 (1.67, 1.82) Pre-existing
hypertension 1.06 (0.78,
1.44) 1.37 (1.14,
1.66) 1.41 (1.19,
1.67) 1.27 (1.07,
1.48) 1.38 (1.20, 1.58) Pre-existing
diabetes 2.54 (1.61,
3.17) 2.62 (2.12,
3.25) 1.97 (1.65,
2.36) 1.95 (1.68,
2.26) 1.62 (1.43, 1.84)
Wood S, Tang. Changes in Rates of cesarean delivery in primiparous women in labor in a Canadian population, 1992–-2018. Obstet Gynecol 2021;137.
The authors provided this information as a supplement to their article.
©2021 American College of Obstetricians and Gynecologists. Page 3 of 3
Appendix 3. Observed and estimated cesarean delivery rates assuming no change from 1992 in rate of cesarean delivery in the second stage of labor. Nulliparous women in labor, singleton pregnancies, vertex presentation, Alberta, 1992–2018.
0%
5%
10%
15%
20%
25%
30%
35%
40%
45%
50%
Year of Birth
