Is HBOT safe during pregnancy?

It depends on the reason. Elective or off-label HBOT during pregnancy is generally avoided — pregnant women are typically excluded from non-emergency protocols, and there's no established safety data in the first trimester. For CO poisoning or decompression sickness during pregnancy, HBOT may be the recommended treatment because the conditions themselves pose higher risk to the fetus than the treatment does.

Is HBOT recommended for CO poisoning during pregnancy?

Yes. The Undersea and Hyperbaric Medical Society recommends HBOT for CO poisoning in pregnancy at lower COHb thresholds than for non-pregnant adults. Carbon monoxide crosses the placenta, and fetal hemoglobin binds CO more tightly than adult hemoglobin. The risk to the fetus from CO exposure is typically greater than the risk from HBOT treatment.

Can I do HBOT for anti-aging or wellness during pregnancy?

No. Elective, off-label, or wellness HBOT is a relative contraindication in pregnancy. There's no evidence of safety in developing fetuses, particularly in the first trimester. Standard obstetric practice is to avoid any non-medically-necessary intervention. Discuss any complementary treatments with your OB.

Why is HBOT a contraindication for elective use during pregnancy?

High concentrations of oxygen carry a theoretical risk of toxicity to developing fetal tissue. Oxygen toxicity in developing systems is a real phenomenon — retrolental fibroplasia in premature infants illustrates the principle, though the fetal risk pathway differs. Because the risk-benefit ratio favors avoidance for non-necessary treatment, pregnant women are excluded from elective protocols.

Hyperbaric Oxygen Therapy During Pregnancy: When It’s Used and When It Isn’t

Pregnancy and HBOT is a situation where context is everything. Two pregnant women could walk into a hyperbaric center and get completely opposite answers — one told HBOT is indicated, the other told to avoid it entirely. Both answers can be correct.

The difference is the underlying condition.

Elective HBOT During Pregnancy: The Short Answer Is No

If you’re pregnant and considering HBOT for an off-label or wellness reason — anti-aging, athletic recovery, Long COVID, or anything not medically necessary — standard obstetric practice is to avoid it.

Pregnant women are routinely excluded from clinical trials and non-emergency hyperbaric protocols. That’s not arbitrary caution. There’s no established safety data for HBOT in human pregnancy during the first trimester, when fetal organogenesis is most active. High oxygen concentrations carry a theoretical risk of toxicity to developing fetal tissue.

The risk isn’t quantified precisely, which is exactly why the standard of care is to avoid exposure. When the potential benefit is optional and the risk is unknown, you skip the treatment.

This applies equally to mild-chamber wellness sessions. The pressure is lower, but the principle is the same — there’s no evidence of safety, and no urgent clinical need to justify the risk.

CO Poisoning During Pregnancy: The Opposite Logic

Carbon monoxide poisoning in pregnancy is one of the clearest indications for HBOT in the hyperbaric medicine literature — and one where the recommendation is stronger than for non-pregnant adults, not weaker.

Here’s why. Carbon monoxide crosses the placenta readily. Fetal hemoglobin has a higher binding affinity for CO than adult hemoglobin does, which means CO accumulates in fetal blood even when maternal levels are relatively lower. It also takes longer to clear.

The UHMS (Undersea and Hyperbaric Medical Society) recommends HBOT for pregnant women with CO poisoning at lower carboxyhemoglobin (COHb) thresholds than for non-pregnant adults. A COHb level that might be managed conservatively in an adult becomes a stronger HBOT indication in pregnancy because of the elevated fetal risk.

In this situation, the risk from HBOT is lower than the risk of not treating. Your OB and the hyperbaric physician will make this decision together based on your specific COHb level, gestational age, and fetal status.

Decompression Sickness During Pregnancy

The same logic applies to DCS in a pregnant diver. Decompression sickness itself poses serious risks to the fetus — particularly embolism and nitrogen bubble formation in fetal circulation. HBOT is the treatment for DCS regardless of pregnancy. Withholding treatment to protect the fetus from HBOT would likely cause greater harm than treating.

Any pregnant woman who has been scuba diving and develops DCS symptoms should be treated as a hyperbaric emergency. Tell emergency responders about the pregnancy immediately so the hyperbaric team can coordinate with obstetrics.

What Makes High Oxygen a Risk in Pregnancy

Oxygen toxicity is a real phenomenon in developing systems. Retrolental fibroplasia — a condition where excess oxygen causes abnormal blood vessel growth in the retinas of premature infants — illustrates how oxygen concentration affects developing tissue. The fetal risk pathway is different from neonatal retinal risk, but the underlying principle holds.

Because HBOT substantially increases tissue oxygen levels, the theoretical risk to fetal development is a legitimate reason to avoid non-necessary exposure. The key word is theoretical — no human study has definitively quantified fetal harm from HBOT during pregnancy. But “not proven harmful” isn’t the same as “proven safe,” and obstetric practice reflects that distinction.

The Decision Is Made Together

If you’re pregnant and facing a situation where HBOT is being discussed, that decision requires both your OB and a hyperbaric physician. Not one or the other. The hyperbaric physician understands the physiological effects of pressurized oxygen. Your OB understands fetal risk at your specific gestational stage.

For emergencies like CO poisoning, this consultation happens fast and the recommendation is usually clear. For any elective consideration, the answer is equally clear — wait until after delivery.

FAQ

Can HBOT cause a miscarriage? There’s no documented causal link between HBOT and miscarriage in humans. But the absence of evidence of harm is not the same as evidence of safety. Elective HBOT isn’t recommended during pregnancy for this and other reasons.

Is it safe to continue HBOT if I find out I’m pregnant mid-protocol? Stop and consult your OB and hyperbaric physician immediately. If you’re being treated for an FDA-approved medical condition, the decision to pause or continue involves weighing the risks of the underlying condition against the pregnancy considerations. Don’t make this decision alone or based on internet research.

What about the pressure itself — is that harmful to a fetus? The pressure changes in HBOT are not the primary concern. The oxygen concentration is. Pressure changes are gradual and controlled. The fetus is in an amniotic fluid environment and doesn’t directly experience the chamber pressure change the way your sinuses and ears do.

Medical Disclaimer: This page provides general information about HBOT and pregnancy. It is not medical advice. Decisions about HBOT during pregnancy require direct consultation with your OB and a qualified hyperbaric medicine physician. For CO poisoning, DCS, or any emergency, call 911 immediately.