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Chapter 8 — 5
Oral Contraceptives
(the "Pill")
The physiological and psychological consequences of these hormonal tablets may have similar
implications to those described above, under "menstruation". In theory, the increased
coagulation effects from the pill could initiate or aggravate DCS. In practice this has not been
observed. There is no relationship between the development of DCS and the taking of oral
contraceptive tablets
per se
. It was considered prudent to cease oral contraceptives in the
female team who undertook a long saturation dive during the Tektite No. 2 project. However,
the absence of males probably made this decision an uncomplicated one.
Decompression Sickness (DCS)
Several studies have shown an increased incidence of DCS in women. Some studies of women
divers showed a more than 3 times increased incidence of DCS compared with men who were
exposed to the same dive profiles. Other studies have not shown this and perhaps the different
observations are due to different cohorts with different dive profiles. For example, females in
the space program seemed to be more susceptible to altitude DCS, and develop more serious
DCS, than men.
Studies on female divers indicated that those who did “reverse profile” dives had more DCS
symptoms than those who did their deeper dives first. In a large series of DCS cases it was
shown that the men so affected dived deeper than the women (almost 3 metres) and it is
possible that their diving exposures and ascent rates were greater.
The weight of evidence does tend to suggest that there might be an increased incidence of DCS
among women
.
There are several possible explanations for this.
Women are frequently less physically fit than men and physical fitness is negatively related to
DCS. Women usually have a higher proportion of subcutaneous body fat (+ 10%) for a given
weight than men, and the body fat has a 4-5 times higher capacity for absorbing nitrogen. Fat
tissue is slower to absorb and to eliminate the nitrogen. Logically, because of the different fat
distribution between the sexes, studies that dealt with certain dive profiles (longer dives) could
have more nitrogen absorbed and a greater incidence of DCS in females. Both reduced physical
fitness and higher fat content probably increase the incidence of DCS .
Navy decompression tables were designed for and tested on physically fit, healthy young male
divers. Strictly speaking, the tables should only apply to this population.
Because of this increased risk, it is wise for women divers to apply extra safety factors when
using the dive tables: e.g. by reducing the allowable bottom time for any depth or by
decompressing for a greater duration. Decompression computer programs should be on the
more conservative settings.
A modern decompression problem has emerged with
breast implants
. Fortunately, gas filled
implants are no longer used, as the barotrauma consequences of diving with these would be
disturbing. However, even silicone filled implants do absorb nitrogen during a dive and a 4%
expansion in the size of these implants has been recorded after dive profiles commonly used by
women sports divers. This is not likely to cause a problem with the implants. However, if these
women were involved in saturation diving there is the potential for significant volume changes
which could lead to damage or rupture of the implant during or after ascent.