Pregnancy and
diving
Should a pregnant woman continue to dive?
Any pregnant woman who would not take any medication or may even
avoid drinking coffee in order to protect her baby (fetus) from
any unknown risk, will still ask if it is safe to dive during
pregnancy?
As a matter of fact, human research is quite defective regarding
the direct effect of diving on the fetus, being a passive
passenger at depth, but most workers investigating DCS and fetal
risk agree that the fetus is not at increased risk.
Let's first discuss the effect of diving on the pregnant mother
and then return back to the effect on the fetus.
*During pregnancy, the mother will experience a change in the
distribution of her body fluids with the increased amount of
interstitial fluids and edema (what is sometimes called the
third-space fluids).
As well, her body undergoes an increase of 5% in deposited fat
during pregnancy.
The combination between this third –space fluid and increased
fat stores will definitely alter both the inert gas intake and
elimination times suggesting an increased risk of DCS for a
pregnant woman.
*Physiological fluid retention during pregnancy also causes the
swelling of the mucous membranes including the naso-pharynx that
will render many diving pregnant women decongestants-dependant
(nasal drops and tablets) with the inherited risk of rebound
congestion (reversed blocks).
*A third problem might be the increased gastro-intestinal
symptoms (in 60% of pregnancies) like nausea, vomiting, heart
burn and reflux which will make riding a boat a night mare and
also will increase the risk of vomiting into the regulator
during diving.
*Another problem is the state of vasodilatation (opening of skin
blood vessels) which puts the pregnant diver at risk of
hypothermia in cool water, and the state of increase in the
basal metabolic rate (excessive heat production) which increases
the risk of hyperthermia in case of heavy activity in warm
water.
*Add to all this the uncomfortable fit of the diving gear as the
weight belt and the wet suit on the expanding belly, as well the
getting tighter wet suit on the already swollen hands and feet
will interfere with the exchange of gases increasing the risks
of limb DCS.
The pregnant diver, especially in the last few months, will also
have some problems in her movements carrying and balancing heavy
equipment and will always suffer the simplest entries and exits
to and from the water.
Effect of diving on the fetus:
*A lot of researchers have investigated the effect of DCS done
to pregnant animals on the offspring to pressures between 6.4 –
7.1 ata (54 – 61 meters) which is in excess of depths
encountered in sport diving. The results suggested an increase
in the rate of fetal deformity when exposure (diving) was done
in early pregnancy (first trimester) while exposure in the last
trimester denoted an increase in the number of still birth of
those animals as a result of lacking of the lung filter of the
fetal circulation which makes the bubbles pass directly to the
brain and heart. These results are still not applicable to
humans so far.
* Another challenge to the diving fetus is the exposure to a
hyperbaric oxygen environment simply as the mother goes
underwater or more dramatically if the mother will have to be
treated from a diving accident in a chamber using oxygen as a
breathing gas. Animal studies showed cardiovascular
malformations and blindness in delivered babies of pregnant
animals who were exposed to hyperbaric oxygen.
*Human data on hyperbaric oxygen and the fetus are very limited,
a case was reported to have been treated from CO toxicity while
pregnant using hyperbaric oxygen with a 5 weeks later delivery
of a normal infant, while a few cases of maternal non-diving
related air embolism cases have been treated with hyperbaric
oxygen and all fetuses died with no adequate explanation of the
definite cause of death!
*Only two surveys have been conducted questioning the outcome of
women who dived while pregnant, although no statistical analysis
was done, the results suggested higher rates of low birth
weight, birth defects, neonatal respiratory difficulties and
other problems in the group that continued to dive while
pregnant.
*One of the hazards that could harm the fetus underwater is the
accidental envenomation of the pregnant mother by a marine
animal, undefined fetal toxic effects may follow, and specific
antitoxins (if any will exist) will also hold risk.
In view of the elective nature of diving, even though diving
during pregnancy does not clearly increase maternal or fetal
incidence of DCS or air embolism, the unborn may be at severe
risk if a diving accident occurs. Summarizing that has been
cited and said,
Pregnant women should not dive.
Dr. Hossam Nasef
