There are seven basic issues a pregnant pilot should consider:
- Size of the abdomen;
- Onset of labor while airborne;
- Blood clots;
- G-force trauma, including seat belts;
- Barometric pressure; and
- Cosmic Radiation (discussed here).
The size of the abdomen is the easiest to understand (and visualize). As the abdomen grows, particularly in the last three months of pregnancy, there can be real concerns -- especially in general aviation operations -- whether full range of motion of the yoke can be obtained. This is an individual call for the GA pilot but some airlines restrict pilots to pregnancies of less than 28 weeks (about six months). The airline restriction is mostly based on the pilot's ability to egress the aircraft and to help passengers after a survival crash. Interestingly, the airlines do not restrict obese pilots from flying, and their stomachs can be more prominent than a pregnant women's at term. Egress can also be an issue for a private aircraft owner if the aircraft is not entry/exit-friendly.
...Timing Is Everything...
Obviously, near the end of a pregnancy, a pilot does not want to schedule a three-night trip overseas. Although labor can start anytime, most labors begin with mild contractions or breaking of the amionic sac (bag of water), giving a fair amount of warning before delivery. Still, to be in the middle of a 14-hour flight to New Zealand or in a foreign hotel may not be the most pleasant situation. For a GA pilot, a local flight can easily be terminated or even a cross-country one reversed. Since most women feel "supercharged" toward the end of pregnancy, energy levels are not usually a factor that will hold back a pilot.
Interestingly, most of the "on-the-aircraft" or "back-of-the-cab" deliveries are the easiest. Fast -- or in medical lingo, precipitous -- deliveries are usually very simple and problem-free. They certainly are not the preferred locations but rarely are there any problems whatsoever. If you are ever caught participating in any way in this kind of a situation, remember two things: One, keep the baby warm and dry after the delivery. Two, you do not need hot water for anything!
Blood clots in the legs and pelvis are not good things but happen to people who are stuck sitting in the same position for long periods of time. This occurs frequently with lengthy travel, whether by air or by auto. Because the enlarging uterus (womb) presses on the venous structures in the pelvis, it restricts blood flow back from the legs. Additionally, the extra estrogen in a pregnant woman's system adversely impacts the body's ability to prevent blood clots. Physical movement is the best prevention if a long flight is mandatory. Ideally, this movement includes walking through the cabin a few times if on an airliner, but even isometric contractions of leg muscles and massaging the legs will help when in a tight GA cockpit for a few hours. Obviously, bidding or planning shorter trips will reduce the risk. (I will not even mention the multiplying effect of tobacco on this problem since everybody already knows you cannot care about a pregnancy if you smoke.)
Hypoxia is not much of a problem for most airline pilots, but it can be for the GA pilot. Experts like Richard Jennings M.D., a former NASA OB/GYN, suggest that oxygen be worn whenever flying at 10,000 feet MSL or more. I tend to be a little more conservative and recommend oxygen at 8,000 feet MSL unless the pregnant pilot lives in a high-altitude location like Jackson, Wyo. Regardless, pulse oximetery is the best option for a pregnant woman to know for sure whether they need oxygen or not.
In general, the fetus will be protected from hypoxia at the expense of the mother by the physiological shunting of oxygen to the fetal circulation via the placenta. Although this may be of marginal benefit, it probably makes a difference in short hypoxic exposures (e.g. 15 minutes while flying through a pass). Since oxygen is cheap and systems can usually be borrowed fairly easily if not owned, why not use it? There is no downside.
...G Forces And Trauma
High G forces such as those done in aerobatics are not recommended. Although no definitive studies have been done in this area, the uterus will move with the body with the G-force movement. More importantly, the pressure of the uterus on the pelvic venous structures during high-positive Gs will induce Gloc (G-force-induced loss of consciousness) much sooner.
The effects of G forces and pregnancy have been studied extensively in automobiles but mainly from a forward sudden deceleration or only with a lap and shoulder harness perspective. They have not looked at five-point restraints as far as I could find. Wearing a simple lap belt is certainly considered safer than not wearing one at all, although many experts suggest not using a shoulder harness during the last three months of pregnancy (put the shoulder strap behind you, just like with a small child). I do not necessarily agree with not using the shoulder harness but I have to defer to the experts. The good news is that studies of pregnant women involved in trauma show amazing resistance to injuries to the fetus unless there are fatal injuries to the mother or penetrating wounds to the abdomen.
Since the fetus is in a liquid world, barometric changes associated with altitude changes are not an issue for a pregnant women or her fetus.
There are essentially no regulations from the FAA in the area of pregnancy and flying. There are general recommendations that include: "It is recommended that the airman obtain a release to fly from the physician caring for her pregnancy. It is further recommended that the airman not fly during the last trimester of pregnancy."
There are a lot of old wives' tales concerning pregnancy and even more about pregnancy and flying. Doctors are not immune, either, as I once learned. This doctor advised a sea-level patient to not to come travel to Jackson Hole, at 6,200 feet MSL, because of the possibility of hypoxic harm to the fetus.
I wonder what does he think happens to women who live here?
First, surgical correction of vision has been around for a while. In recent years, it has become much more common due a new technique called LASIK. LASIK is a procedure that reshapes the cornea from the inside after a corneal flap is cut. It is all done with a laser and computer-assisted control (i.e., the CNC machining of the eye) and has minimal recovery time.
One of the options for LASIK is to correct one eye for distance vision and correct the other for close vision, thereby creating a "monovision" pilot. This allows the pilot to see clearly in the distance with one eye and close up with the other. Although it sounds strange, many patients love having the vision dichotomy and adjust to it very easily.
The problem with monovision is depth of field. The FAA has a ban on "monovison" and bifocal contacts specifically for this reason. The difference, according to Dr. Silberman, is that surgically-created monovision is similar to monocular (single-eyed) vision when it comes to depth perception. Because the surgical change is permanent, after a six-month adjustment period, the FAA will approve a pilot with monovision correction. Prior to the six-month period, the pilot must wear differentiating glasses which covert the monovision to "straight" vision while operating an aircraft. All non-piloting time should be without the glasses so the pilot can adapt depth perception in environments that are not so critical for depth perception.
When asked specifically why monovision LASIK pilots can be approved but monovision contact lenses are not, Dr. Silberman commented that he has no control over how long someone wears monovision contacts since they can be worn at the whim of the pilot. Thus, there is no way for the FAA to ensure whether the pilot has good, stable depth perception when he or she wears the monovision lenses.
Dr. Silberman also has streamlined the process for regular LASIK approval. For pilots who are corrected for the same vision in both eyes, they can be approved for flight by their local AME. Pilots should be stable and not have side effects from the surgery. Silberman prefers a letter (over the form 8700) from the treating physician that states the corrected vision, the occurrence of side effects (or lack thereof), and that vision is stable. This letter can be presented to the AME who then makes a chart note, forwards the eye doctor's letter to the FAA, and -- viola! -- the pilot can fly. The pilot will eventually receive a letter from the FAA which formally approves the change but, according to Silberman, the pilot is legal as soon as the AME has seen the pilot and approved him for flight.
Dr. Silberman noted that he knows that many pilots do not notify the FAA of the surgery until the next scheduled AME exam which technically is a violation of 61.5.3 concerning a change in medical condition. Dr. Silberman told AVweb that, while he is not "thrilled" about it, it is probably okay. The only problem, he noted, was if the pilot was ramp checked and did not have his or her old glasses in the cockpit. Since the glasses are useless to a pilot who has had LASIK, it might be a good place to store them until the next medical certificate is issued!