Hyperbaric oxygen therapy (HBOT), the administration of 100% oxygen at pressures greater than atmospheric levels, is an established treatment for various acute and chronic conditions. However, its use during pregnancy remains controversial due to potential risks to fetal development, including oxidative stress, teratogenicity, and altered placental hemodynamics. This chapter explores the physiological implications of HBOT during pregnancy, as well as the peripregnancy period, examining both its therapeutic potential and safety concerns. While generally contraindicated during the first trimester, HBOT may be cautiously considered in life-threatening scenarios such as carbon monoxide poisoning, gas gangrene, and decompression sickness, where maternal and fetal survival is at stake. Emerging research suggests additional areas of interest, including HBOT’s possible benefits in reproductive health and fertility, though these findings remain preliminary. The chapter also highlights the need for individualized risk–benefit assessments, strict monitoring protocols, and interdisciplinary management when HBOT is administered during pregnancy.