The effects of controlled hyperbarism on pregnant women and fetal development are uncertain.

In eastern Europe, scientists using relatively low pressures but repeatedly and for long periods of time have reported no particular problems with it.

One study suggests that while in a hyperbaric atmosphere, the fetus changes its’ circulatory flow in the direction of neonatal flow patterns (with narrowed or closed ductus arteriosus and foramen ovale). Upon return to normal barostatus, the flow again reverses to the normal fetal flow pattern. Whether this change poses any long-term problems for the fetus is unknown.

Based on these concerns, it is inadvisable to allow any pregnant woman to dive or enter a hyperbaric chamber unless strongly indicated for medical reasons. If an accident occurs in which it would be desirable to place the pregnant woman in a hyperbaric chamber, the risks to the fetus (mainly theoretical) must be balanced against the risks to the mother of not undergoing hyperbaric treatment.