Table 7Route of birth in women using nitrous oxide

Author
Year
Study Type
Intervention (N)Vaginal Birth N (%)Assisted Vaginal Birth N (%)Cesarean Birth N (%)
Leong et al.,56
2000
Prospective cohort
Entonox plus IM pethidine (68)56 (82.4)9 (13.2)3 (4.4)
Bupivacaine epidural (55)28 (50.9)22 (40.1)*5 (9.0)
Abboud et al.,40
1995
RCT
Nitrous oxide, 30-60% oxygen (40)35 (87.5)5 (12.5)0^
Desflurane 1-4.5% and oxygen (40)31 (77.5)9 (22.5)0^
Ranta et al.,58
1994
Prospective cohort
Nitrous oxide 50% (210)NR (95)NR (2)NR (3)
Water blocks (69)NR (90)NR (3)NR (7)
Pethidine (50)NR (91)NR (2)NR (7)
Paracervical block (128)NR (94)NR (3)NR (3)
Epidural anesthesia (82)NR (80)NR (11)NR (9)
Several methods (339)NR (86)NR (7)NR (7)
No analgesia (213)NR (94)NR (1)NR (5)
Harrison et al.,62
1987
Prospective cohort
Entonox (20)12 (60.0)7 (35.0)0
TENS (50)32 (64.0)14 (28.0)4 (8.0)
Pethidine plus promazine (50)32 (64.0)18 (36.0)0
Lumbar epidural (50) 13 (26.0)31 (62.0)θ3 (6.0)θ
Rosen et al.,66
1969
Nonrandomized clinical trial
Nitrous oxide 50% (265)235 (88.7)30 (11.3)0
Trichloroethylene 0.35% or 0.5% (394)345 (87.5)46 (11.7)3 (0.8)
Methoxyflurane 0.35% (598)525 (87.8)68 (11.4)5 (0.8)
Jones et al.,54
1969
Quasi-RCT
Nitrous oxide calibrated in 5% steps from 20% to 100% oxygen (24)19 (79.2)5 (20.8)0^
Methoxyflurane with 40% oxygen (24)19 (79.2)5 (20.8)0^

NR = not reported; RCT = randomized controlled trial

*

p < 0.01

^

Study only included women with vaginal births.

One woman in the Entonox group and three women in the lumbar epidural group had breech births that are not included in the table because the route of birth was not identified.

θ

The operative birth rate (which included forceps- and vacuum-assisted births, cesarean births, and breech births) was higher for women whose initial choice was epidural than any of the other analgesia methods (p < 0.001).

From: Results

Cover of Nitrous Oxide for the Management of Labor Pain
Nitrous Oxide for the Management of Labor Pain [Internet].
Comparative Effectiveness Reviews, No. 67.
Likis FE, Andrews JC, Collins MR, et al.

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