The question of scuba diving while pregnant has a simple answer: both the American College of Obstetricians and Gynecologists and the Divers Alert Network (DAN) recommend no scuba diving for the duration of the pregnancy. This article aims to explain a little bit more about the potential risks and complications, and shed some light onto why it’s thought that diving and pregnancy don’t mix. It’s worth pointing out that although it’s unwise to dive once you know you’re expecting, those women who unwittingly dive during the first few weeks of their pregnancy should not panic — the general consensus is that diving at this early stage should have no serious ramifications on the developing fetus. It’s hard to know the precise effects of diving past those first few weeks, as there is no experimentation on pregnant women for obvious reasons. The advice of medical organizations like DAN is therefore based on anecdotal evidence, surveys of women who have dived while pregnant, and studies carried out on animals. Due to the sometimes-biased nature of surveys and the differences between animal and human anatomy, there are flaws in the research on diving and pregnancy, and much unsubstantiated conjecture. However, the fact that diving might pose a risk to an unborn child is a good enough reason to stay out of the water.
Survey Results of Scuba Diving While Pregnant
Surveys asking women about their experiences scuba diving while pregnant are somewhat inconclusive. No adverse reactions were reported in many cases, while in others, miscarriages or fetal deformation occurred, but this may or may not have been caused by diving. In1980, Undersea Biomedical Research journal conducted a survey entitled “Scuba diving and fetal well-being,” which studied 208 women, including 109 who had dived during pregnancy. Of these, the women who had not dived reported no birth defects, while there was a 5.5 percent incidence of problems amongst those women who had dived. However, it’s worth noting that diving could not conclusively be said to be responsible for the issues, which could have been the result of any number of unrelated factors.
It is thought that the potential negative effects of scuba diving while pregnant mainly affect fetuses in the first and third trimester. In the first trimester, the effects of oxygen concentrated by pressure could trigger defects in the developing fetus, including reduced weight, abnormal skull development, malformed limbs and the abnormal development of the heart. And at any time, but particularly in the third trimester, decompression sickness in the mother could cause major problems for the fetus due to its inability to filter out nitrogen bubbles through the lungs, as an unborn baby’s blood bypasses the lungs and oxygenates via the placenta instead.
That the placenta plays a key role in fetal-blood circulation explains why sheep have been used in experiments attempting to ascertain the effects of decompression sickness on pregnant women. Sheep placentae are similar to human placentae, and the results of studies on pregnant sheep in hyperbaric chambers have shown that even in instances where the mother showed no signs of decompression illness, bubbles were often present in the bloodstream of the offspring. When mothers did show signs of DCI, the symptoms were even more aggravated in the fetus. Often, the effects of DCI in the offspring manifested as life-threatening heart arrhythmias, weakened limbs and spinal defects. Because the fetus cannot rely on its lungs to filter bubbles from its blood, even ‘silent bubbles’ that are harmless in adults could cause potentially fatal arterial gas embolisms for the unborn baby. In terms of the effects of oxygen concentrated by pressure on the fetus, research carried out on rodents suggests that exposure could interfere with normal development of tissues. When the exposure happens, i.e., at which stage of development, seems to dictate which defects occur as a result. In some rodent case studies, exposure did not affect development at all.
Ultimately, although we cannot know with absolute certainty the full extent of the risks involved when it comes to scuba diving while pregnant, all signs say that it’s best avoided until your baby is safely delivered. Mothers should also be prepared to wait between 4 to 8 weeks after giving birth before getting back in the water, depending on the nature of the delivery; equally, it is always advisable to seek medical advice before resuming diving.