Years ago, as an undergrad we were required to write a research paper in our ENX101 class. I chose the topic of pregnancy and diving, wondering if the statement which I heard when going through my Basic Open Water class "no diving while pregnant because there is no information or research on the topic" is true or not. When I became an instructor I heard the same thing. Before writing my paper I did a lot of reading on the issue. There have been some studies in retrospect on the topic.
Here is something I learned, the fetus can get decompression sickness while the mother may not. How does one determine if the fetus is bent or not? If the mother isn't why would she suspect her fetus is. If the mother has the malady that can determined. Here is the main concern, to treat decompression sickness the mother, along with her fetus, obviously, are placed into a chamber and treated at pressure while breathing pure oxygen during the treatment. During growth a fetus is very sensitive to high concentrations of oxygen. Too much O2 can leave the fetus blind after birth.
In the studies on goats, and the retrospect surveys with woman, showed no maladies or abnormal effects from diving on the infant after birth. One lady, who had a rapid ascent from 50' (during the second trimester, if I remember correctly), had a baby that suffered from deformities. It was determined that her birth fell into the small percentage of babies born with deformities, meaning it could not be determined whether or not the diving and/or the rapid ascent were the cause of the abnormality.
While it is true that no direct studies have been conducted on women who dive while pregnant, there is scant information that suggests the chance of injury or otherwise is minimal during the first trimester; second and third trimester are unknown. The question for each mother is whether or not it is worth the risk given very little information as to how safe or risky breathing compressed gas under pressure is for her developing fetus.
I still have the paper if you are interested.
