1 Appendix 1. Sensitivity analysis restricted to low-risk women. Associations between
individual and organizational characteristics and labor analgesia methods: multinomial multilevel multivariable analysis of complete cases
NPA alone NA+NPA combined
n= 402 n= 1 844
aOR 95% CI aOR 95% CI
Maternal characteristics
Maternal age, years
< 30 Ref — Ref —
≥ 30 0.97 (0.70 - 1.34) 0.84 (0.73 - 0.96)
Parity and antenatal class attendance
Nulliparous without AC Ref — Ref —
Nulliparous with AC 1.10 (0.57 - 2.11) 1.39 (1.11 - 1.76) Multiparous without AC 1.33 (0.69 - 2.56) 0.54 (0.42 - 0.69) Multiparous with AC 2.50 (1.27 - 4.93) 1.06 (0.81 - 1.40)
Nationality
French Ref — Ref —
Other 0.37 (0.21 - 0.65) 0.83 (0.67 - 1.04)
2
Educational level
≤ Middle school 0.88 (0.39 - 1.99) 0.73 (0.52 - 1.03)
High school Ref — Ref —
1 to 4 years post-graduation 1.42 (0.99 - 2.05) 1.21 (1.03 - 1.42) ≥ 5 years post-graduation 2.06 (1.33 - 3.20) 1.37 (1.12 - 1.67)
Low socio-economic status
Yes 0.93 (0.60 - 1.42) 0.78 (0.64 - 0.95)
No Ref — Ref —
Antenatal preference for pain relief
Antenatal preference for NA
Absolutely yes Ref — Ref —
Maybe yes 4.01 (2.73 - 5.88) 1.50 (1.29 - 1.75)
Not preferred 58.58 (39.80 - 86.21) 1.66 (1.33 - 2.07)
Obstetric characteristics
Inadequate antenatal care
Yes 0.78 (0.37 - 1.65) 0.62 (0.43 - 0.89)
No Ref — Ref —
Labor management
Spontaneous labor ≤ 5 cm without oxytocin Ref — Ref —
3 Spontaneous labor > 5 cm without oxytocin 6.15 (4.25 - 8.91) 0.82 (0.59 - 1.15) Spontaneous labor with oxytocin 0.12 (0.08 - 0.19) 1.42 (1.23 - 1.65) Oxytocin induction 0.20 (0.10 - 0.40) 1.04 (0.80 - 1.35)
Organizational characteristics
Maternity unit status
Public 1.94 (1.31 - 2.87) 1.58 (1.26 - 1.98)
Private Ref — Ref —
Anesthesiologist availability*
Dedicated to delivery unit Ref — Ref —
Not dedicated to delivery unit 1.46 (1.05 - 2.05) 1.08 (0.88 - 1.32)
Midwife workload **
Very high 0.42 (0.22 - 0.79) 0.86 (0.59 - 1.26)
High 1.09 (0.68 - 1.73) 0.79 (0.56 - 1.09)
Intermediate Ref — Ref —
Low 0.97 (0.63 - 1.49) 1.08 (0.83 - 1.40)
Very low 1.70 (1.08 - 2.68) 0.93 (0.69 - 1.26)
Random effects
Second-level variance‡ τ00 0.23 0.55
PCV‡‡ (0-4) 70% 0%
4 Model adjusted on all the characteristics presented in appendix 1: maternal age, parity, nationality,
educational level, low socio-economic status, antenatal preference for NA, inadequate antenatal care, labor management, maternity status, anesthesiologist availability, midwife workload
aOR: adjusted odds ratio, CI: confidence interval NA, Neuraxial Analgesia
NPA, Non-Pharmacological Analgesia AC, antenatal class attendance
* Anesthesiologist availability at woman's admission in delivery unit
** Midwife workload expressed as the ratio of the number of midwives per shift per 100 annual deliveries:
very high= < 10th percentile, high= 10th to 24th percentile, intermediate= 25th to 74th percentile, low=75th to 89th percentile and very low ≥ 90th percentile
‡ Variance of the empty model: 0.77 and 0.55 respectively for NPA alone and NA+NPA
‡‡ Proportional change of variance defined as τ00(0) - τ00(n))/ τ00(0)
¥ Characteristics in the model do not explain variance (negative result) Number of observations used= 5,765/6,047
5 Appendix 2. Associations between individual and organizational characteristics and the use of NPA alone (compared to NA alone): binary multilevel multivariable logistic regression of complete cases.
NPA alone
n= 559
aOR 95% CI
Maternal characteristics
Maternal age, years
< 30 Ref —
≥ 30 1.19 (0.89 - 1.60)
Parity/antenatal class attendance
Nulliparous without AC Ref —
Nulliparous with AC 2.31 (1.23 - 4.34)
Multiparous without AC 2.41 (1.30 - 4.48)
Multiparous with AC 4.16 (2.17 - 7.95)
Nationality
French Ref —
Other 0.49 (0.30 - 0.79)
Educational level
≤ Middle school 0.91 (0.49 - 1.69)
6
High school Ref —
1 to 4 years post-graduation 0.98 (0.71 - 1.36) ≥ 5 years post-graduation 1.59 (1.07 - 2.37)
Low socio-economic status
Yes 0.90 (0.62 - 1.30)
No Ref —
Antenatal preferences
Antenatal preference for NA
Absolutely yes Ref —
Maybe yes 4.28 (3.05 - 6.02)
Not preferred 70.84 (49.38 - 101.63)
Obstetric characteristics
Individual risk level
Low risk 1.21 (0.91 - 1.60)
High risk Ref -
Inadequate antenatal care
Yes 1.14 (0.62 - 2.07)
No Ref —
7
Labor management
Spontaneous labor ≤ 5 cm without oxytocin Ref — Spontaneous labor > 5 cm without oxytocin 6.56 (4.70 - 9.17) Spontaneous labor with oxytocin 0.12 (0.08 - 0.17)
Oxytocin induction 0.15 (0.08 - 0.28)
Organizational characteristics
Maternity unit status
Public 1.85 (1.23 - 2.78)
Private Ref —
Anesthesiologist availability*
Dedicated to delivery unit Ref —
Not dedicated to delivery unit 1.79 (1.27 - 2.52)
Midwife workload**
Very high 0.51 (0.27 0.97)
High 1.54 (0.93 2.55)
Intermediate Ref —
Low 1.20 (0.77 1.86)
Very low 2.12 (1.34 3.35)
8 Model adjusted on all the characteristics presented in appendix 2.a: maternal
age, parity, nationality, educational level, low socio-economic status, antenatal preference for NA, individual risk level of pregnancy, inadequate antenatal care, labor management, maternity status, anesthesiologist availability, midwife workload
aOR: adjusted odds ratio, CI: confidence interval NA, Neuraxial Analgesia
NPA, Non-Pharmacological Analgesia AC, antenatal class attendance
* Anesthesiologist availability at woman's admission in delivery room
** Midwife workload expressed as the ratio of the number of midwives per shift per 100 annual deliveries: very high= < 10th percentile, high= 10th to 24th percentile, intermediate= 25th to 74th percentile, low=75th to 89th percentile and very low ≥ 90th percentile
Number of observations used= 6,023/6,355
9 Appendix 3. Associations between individual and organizational characteristics and the use of NA+NPA (compared to NA alone): binary multilevel multivariable logistic regression of complete cases.
NA+NPA combined
n= 2,753
aOR 95% CI
Maternal characteristics
Maternal age, years
< 30 Ref —
≥ 30 0.91 (0.82 - 1.02)
Parity/antenatal class attendance
Nulliparous without AC Ref —
Nulliparous with AC 1.47 (1.21 - 1.78)
Multiparous without AC 0.62 (0.51 - 0.76)
Multiparous with AC 1.23 (0.99 - 1.54)
Nationality
French Ref —
Other 0.85 (0.71 - 1.01)
10
Educational level
≤ Middle school 0.84 (0.65 - 1.08)
High school Ref —
1 to 4 years post-graduation 1.20 (1.06 - 1.36) ≥ 5 years post-graduation 1.40 (1.19 - 1.65)
Low socio-economic status
Yes 0.86 (0.74 - 1.00)
No Ref —
Antenatal preferences
Antenatal preference for NA
Absolutely yes Ref —
Maybe yes 1.45 (1.28 - 1.64)
Not preferred 1.85 (1.54 - 2.22)
Obstetric characteristics
Individual risk level
Low risk 1.03 (0.92 - 1.14)
High risk Ref —
Inadequate antenatal care
Yes 0.71 (0.53 - 0.95)
11
No Ref —
Labor management
Spontaneous labor ≤ 5 cm without oxytocin Ref — Spontaneous labor > 5 cm without oxytocin 0.82 (0.62 - 1.08) Spontaneous labor with oxytocin 1.48 (1.31 - 1.67)
Oxytocin induction 1.00 (0.82 - 1.21)
Organizational characteristics
Maternity unit status
Public 1.52 (1.23 - 1.88)
Private Ref —
Anesthesiologist availability*
Dedicated to delivery unit Ref —
Not dedicated to delivery unit 1.01 (0.84 - 1.22)
Midwife workload **
Very high 0.90 (0.62 - 1.30)
High 0.92 (0.67 - 1.25)
Intermediate Ref —
Low 1.13 (0.88 - 1.44)
Very low 1.16 (0.88 - 1.52)
12
Model adjusted on all the characteristics presented in appendix 2b:
maternal age, parity, nationality, educational level, low socio-economic status, antenatal preference for NA, individual risk level of pregnancy, inadequate antenatal care, labor management, maternity status,
anesthesiologist availability, midwife workload
aOR: adjusted odds ratio; CI: confidence interval NA, Neuraxial Analgesia
NPA, Non-Pharmacological Analgesia AC, antenatal class attendance
* Anesthesiologist availability at woman's admission in delivery unit
** Midwife workload expressed as the ratio of the number of midwives per shift per 100 annual deliveries: very high= < 10th percentile, high=
10th to 24th percentile, intermediate= 25th to 74th percentile, low=75th to 89th percentile and very low ≥ 90th percentile
Number of observations used=8,205/8,641