Background We systematically reviewed evidence addressing the effectiveness of nitrous oxide for the management of labor pain, the influence of nitrous oxide on women's satisfaction with their birth experience and labor pain management, and adverse effects associated with nitrous oxide for labor pain management. Methods We searched the MEDLINE, EMBASE, and Cumulative Index to Nursing and Allied Health Literature (CINAHL) databases for articles published in English. The study population included pregnant women in labor intending a vaginal birth, birth attendees or health care providers who may be exposed to nitrous oxide during labor, and the fetus/neonate. Results We identified a total of 58 publications, representing 59 distinct study populations: 2 studies were of good quality, 11 fair, and 46 poor. Inhalation of nitrous oxide provided less effective pain relief than epidural analgesia, but the quality of studies was predominately poor. The heterogeneous outcomes used to assess women's satisfaction with their birth experience and labor pain management made synthesis of studies difficult. Most maternal adverse effects reported in the literature were unpleasant side effects that affect tolerability, such as nausea, vomiting, dizziness, and drowsiness. Apgar scores in newborns whose mothers used nitrous oxide were not significantly different from those of newborns whose mothers used other labor pain management methods or no analgesia. Evidence about occupational harms and exposure was limited. Conclusions The literature addressing nitrous oxide for the management of labor pain includes few studies of good or fair quality. Further research is needed across all of the areas examined: effectiveness, satisfaction, and adverse effects.

Nitrous Oxide for the Management of Labor Pain: A Systematic Review

Umbilical cord pH, PCO2, and bicarbonate following uncomplicated term vaginal deliveries.

Fetal and neonatal biochemistry and Apgar scores.

Background. Although several investigators have attempted to define the normal values of umbilical cord blood pH and gases, there is considerable controversy about the optimal cutoff values to diagnosis intrauterine asphyxia. A possible reason for this might be that several studies have included data from fetuses born after different duration of labor.Objective To determine the effect of labor and the duration of second stage of labor on umbilical arterial acid-base status at birth in healthy term infants.Methods Umbilical artery acid-base status was determined in patients (n = 356) who met the following criteria: 1) singleton term pregnancy with no significant medical, obstetric, or neonatal complications; 2) vertex presentation if delivered vaginally; 3) neither regional nor general anesthesia applied if delivered vaginally; 4) no use of oxytocin; 5) normal fetal heart rate patterns; 6) clear amniotic fluid; 7) Apgar scores at 1 and 5 min ≥7; 8) appropriate fetal weight for gestational age. Patients wer...

The effect of labor on the normal values of umbilical blood acid-base status

Pain relief for labour is freely available in the United Kingdom, principally because of the widespread use of systemic agents, like pethidine, and self-administered inhalation analgesia. These methods have enabled midwives, who, after all, deliver the majority of babies, to provide a substantial degree of pain relief for most mothers associated with an impressive record of safety (Arthure et al., 1969). But there remains a substantial minority of mothers who are not satisfied with their pain relief. Although other procedures are available, it is by improvements in these basic methods, and their application, that there lies most hope of a rapid improvement in results. This article mainly describes advances which have appeared since previous reviews (Crawford, 1965; Crawford, 1966a; Utting and Gray, 1968; Bonica, 1969).

Recent advances in pain relief in childbirth i: inhalation and systemic analgesia

SUMMARY Sixty-four patients received methoxyflurane analgesia and/or anaesthesia for labour and delivery Analgesia with methoxyflurane-air produced satisfactory analgesia for labour and delivery in the multigravidae of Group I Foetal and maternal blood levels did not increase with increased duration of inhaler use, apparently due to the absence of pain-induced hyperventilation Patients in Group II required the addition of light methoxyflurane, nitrous oxide and oxygen anaesthesia This resulted in the highest foetal memoxyflurane levels of the three groups, and the highest rate of neonatal depression Group III patients arrived with delivery imminent, and were given light methoxyflurane, nitrous oxide and oxygen anaesthesia Despite high maternal levels of methoxyflurane, foetal levels were no higher than in Group I, presumably because of the short duration of exposure Methoxyflurane has little effect on the foetus if low concentrations are administered to the mother, or if the duration of higher concentrations is kept short

The effect of methoxyflurane on the foetus

Neonatal acid-base studies. I. Effect of normal labor and obstetric manipulation.

An evaluation of methoxyflurane analgesia and anesthesia for obstetrics.

Neonatal acid-base studies. ii. effect of a heavy medication narcotic antagonist regimen for labor and delivery

over the years, as the principles of resusCitation were elucidated. It has been obvious only in the last one or two decadea that what is really needed in resuscitation is clearing of the airway and inflation of the lungs, and not anal dilatation, severe slapping, conhast baths, or intragastric oxygen pulmonary resuscitation, in the form of inflation of the lungs in the apneic newborn,' or assisted respiration in the hypoventilating newborn, is now standard procedure and not likely to be displaced.

W.E. Brown

Papers

The effect of methoxyflurane on the foetus

Neonatal acid-base studies. I. Effect of normal labor and obstetric manipulation.

An evaluation of methoxyflurane analgesia and anesthesia for obstetrics.

Neonatal acid-base studies. ii. effect of a heavy medication narcotic antagonist regimen for labor and delivery

Experiences with chemical resuscitation of the newborn.