Supplemental oxygen is safe during pregnancy when it’s medically needed, but it should not be used routinely or at high doses without a clear reason. Your body’s oxygen demands increase significantly during pregnancy, with a 20% rise in oxygen consumption and a 15% jump in metabolic rate. That means maintaining adequate oxygen levels matters more than ever, but giving too much oxygen carries its own risks for both you and your baby.
Why Pregnant Women Sometimes Need Oxygen
Several situations can lower your blood oxygen levels enough to warrant supplemental oxygen during pregnancy. Asthma flare-ups are one of the most common. In pregnant women with acute asthma, clinicians aim to keep oxygen saturation above 95%, and a blood oxygen level below 70 mm Hg is considered severe. Other situations include pneumonia, COVID-19, heart conditions, sleep apnea, and complications during labor and delivery.
The general target for pregnant patients is an oxygen saturation above 95% with a blood oxygen pressure above 75 mm Hg. These thresholds are slightly higher than for non-pregnant adults because oxygen has to cross the placenta to reach your baby, and that transfer is less efficient when maternal levels drop even modestly.
The Problem With Too Much Oxygen
Oxygen is essential, but excessive amounts are toxic. Animal research has shown that maternal hyperoxia (prolonged exposure to high oxygen concentrations) can cause growth problems and heart dysfunction in offspring. In mouse studies, high oxygen exposure damaged the energy-producing structures inside fetal heart cells, leading to reduced cardiac function and lower birth weight. These findings are from animal models and haven’t been replicated in large human trials, but they reinforce a principle that already guides clinical practice: oxygen should be used at the lowest dose needed to maintain healthy saturation levels.
This is why the American College of Obstetricians and Gynecologists now recommends against giving oxygen routinely during labor when the baby’s heart rate looks concerning, unless the mother herself has low oxygen levels. For years, it was common practice to put an oxygen mask on laboring women whenever fetal heart rate tracings looked abnormal. ACOG classified this as a strong recommendation backed by high-quality evidence, meaning the old “just in case” approach has been formally retired.
Oxygen for Asthma and Respiratory Conditions
If you have asthma or another respiratory condition, oxygen therapy during a flare-up is not only safe but important. Poorly controlled asthma poses a bigger threat to your pregnancy than the oxygen used to treat it. The goal during an asthma emergency is to keep your saturation above 95% while your other treatments take effect. If your breathing worsens enough that you need emergency care, expect repeated breathing tests and possibly fetal monitoring alongside your asthma treatment.
For pregnant women with sleep apnea, the concern is repeated drops in oxygen during the night. These dips have been linked to fetal heart rate changes and, in some cases, to preeclampsia and low birth weight. The standard treatment is CPAP (a pressurized air mask worn during sleep), not supplemental oxygen on its own. CPAP has been shown to reduce the blood pressure spikes associated with preeclampsia during sleep and improve nighttime cardiac output.
High Altitude and Air Travel
Traveling to high elevations reduces the oxygen available in every breath you take. The CDC advises that pregnant women avoid sleeping at altitudes above 3,050 meters (about 10,000 feet) and should only travel to high altitudes after confirming the pregnancy is low-risk. In most high-altitude towns and resorts, supplemental oxygen is available for short-term use and is effective at restoring normal oxygen levels and preventing altitude sickness.
Commercial aircraft cabins are pressurized to the equivalent of about 1,800 to 2,400 meters (6,000 to 8,000 feet), which causes a mild drop in blood oxygen for everyone on board. Most healthy pregnant women tolerate this without any issues. If you have a lung condition that already lowers your oxygen, you can bring a portable oxygen concentrator on board. You’ll need a signed statement from your doctor confirming the medical need, and you should notify the airline in advance. Most airlines require medical documentation for flying after 28 weeks of pregnancy regardless of oxygen use.
Hyperbaric Oxygen: A Special Case
Hyperbaric oxygen therapy, which delivers pure oxygen at pressures higher than normal atmosphere, is a different situation entirely. It is generally not recommended during pregnancy except for carbon monoxide poisoning, where the risk of not treating is far greater than the risk of the therapy itself. Published case reviews have found that sessions lasting 30 to 180 minutes at standard treatment pressures did not cause measurable harm to mothers or fetuses. However, complications have been reported, including uterine contractions during treatment and, in one case involving severe placental problems, an extremely premature delivery. Potential risks also include seizures from high oxygen concentrations and, for premature infants, a specific type of eye damage.
Because the safety data is limited mostly to carbon monoxide cases, hyperbaric centers typically decline to treat pregnant patients for other conditions. If you’re ever in a situation where hyperbaric oxygen is suggested during pregnancy, the decision should involve careful weighing of whether the condition being treated poses a greater immediate danger than the therapy itself.
What This Means in Practice
If you’ve been prescribed supplemental oxygen for a diagnosed condition like asthma, sleep apnea, or a heart problem, continuing or starting that therapy during pregnancy is appropriate and protective. The key principle is that oxygen should be titrated to keep your saturation in the target range (above 95%) rather than administered freely at high flow rates. Low-flow oxygen used to correct genuinely low levels is a routine and well-supported intervention in pregnancy.
What you want to avoid is using oxygen when your levels are already normal, treating it as a wellness boost, or assuming that more is better. Your body and your baby are designed to function within a specific oxygen range, and staying within that range, not above it, is the goal.