Review Article
Pro-Con Debate: Nitrous Oxide for Labor Analgesia
Table 1
Nitrous oxide relative contraindications during pregnancy.
| Condition | | Prevalence |
| Metabolic Risk | | | | Low vitamin B12 | 29% | | Low folate | 6.4% | | Hyper Homocysteinemia | 21% |
| Genetic Risk | | | | MTHFR homozygous polymorphisms 677C>T, 1298A>C | 20% western Europe | | Non-Hispanic white CDC | 22% | | Non-Hispanic black CDC | 4.6% | | Mexican American CDC | 23.4% | | Fetal MTHFR polymorphism | Consider parental heritage |
| Cardiovascular risk | | | | Preeclampsia spectrum | 5-10% | | Hypertension 20-44 y.o.F | 10.4% | | Hypercholesterolemia 20-44 y.o. F | 9% |
| Drugs of Abuse (NMDA Antagonists) history | | | | Ethanol use pregnancy CDC | 10% | | Phencyclidine/hallucinogen | 0.5% | | Nitrous oxide general population | 4-8% | | Nitrous oxide UK | Second to cannabis |
| Medical condition | | | Closed space (nitrous causes expansion) | e.g. COPD, asthma attack, occlusion of middle ear e.g. infection | |
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