Nitrous oxide sedation is contraindicated in which period of pregnancy?

Nitrous oxide sedation is contraindicated in which period of pregnancy?

• A. Second trimester
• B. First trimester
• C. Third trimester
• D. Postpartum period

Answer: (B)

Fetal safety during early development is the big idea here. Nitrous oxide can interfere with folate-dependent processes by inactivating vitamin B12–dependent enzymes, which disrupts DNA synthesis in rapidly dividing embryonic cells. This makes the first trimester, when organogenesis is occurring, a particularly sensitive period. Because of this, nitrous oxide sedation is contraindicated in the first trimester. In later stages of pregnancy, the fetus is less susceptible to this mechanism, so use is considered with caution and minimal exposure. The postpartum period is after delivery, so it’s not a period of pregnancy.

Fetal safety during early development is the big idea here. Nitrous oxide can interfere with folate-dependent processes by inactivating vitamin B12–dependent enzymes, which disrupts DNA synthesis in rapidly dividing embryonic cells. This makes the first trimester, when organogenesis is occurring, a particularly sensitive period. Because of this, nitrous oxide sedation is contraindicated in the first trimester. In later stages of pregnancy, the fetus is less susceptible to this mechanism, so use is considered with caution and minimal exposure. The postpartum period is after delivery, so it’s not a period of pregnancy.