I am just returning from yet another trip to Europe, Belgium this time!  This has been my 9^th transatlantic trip this year.  Last year I made 10 trips, and the year before that 11.  With an average of a trip every 6-8 weeks I spend a lot of time either sat in a plane or at an airport or, trying not to fall asleep in meetings whilst I try to get over the jet lag!!

Travelling like this is stressful.  I always have a connection to make in the US because I do not live near an international airport, and sometimes I have another connection in Europe as I travel to cities that do not connect directly with the USA so I can often end up with 2 transfers…it can be very stressful making these connections when flights get delayed or security lines hold me up.  For example on this particular trip to Belgium, due to a series of unfortunate and unrelated disruptions it took me 9 hours longer to reach my destination (on top of the planned 14 hours of travel).

I am simply sick and tired of it.  Yes, I get to go visit some cool cities, I am grateful for that opportunity, but it is physically disruptive to my life.  As this is my last trip of the year and I already have 7 trips planned in the first 5 months of next year :-s I am beginning to wonder whether it is such a good idea to do all this travelling.  I am not sure how many of these I will be able to commit to with my next round of IVF coming up.

This got me thinking about how little I know about the effects of flying on my fertility.  Is it even an issue?  Should I be concerned?  So I did a bit of research and here is what I have found so far:

There is currently no overwhelmingly strong evidence that flying has a direct cause of reduced fertility.  However, there are a few studies that indicate that there may be some correlation.

One study I found to be compelling used mice to investigate whether shifting the body clock has an effect on their fertility [1].  The results of this study showed that there may be serious implications for a woman’s reproductive health if her work involves shift work or time zone changes.

To understand the outcome of this study, you need to understand the body clock.  Our body clocks are called circadian rhythms, these are physical, mental and beahvioural changes that follow a roughly 24 hour cycle, responding primarily to light and darkness in the environment.  Your circadian rhythm is produced by your body, but it is also influenced by the environment.  Light is the main thing that influences circadian rhythms – it turns on or off genes that control your internal clock.  Your circadian rhythm can change your sleep-wake cycles hormone release, body temperature and other important bodily functions [2].  (I know travelling certainly screws up my body temperature because I discovered this last year when we were trying to conceive the good old way and I was actually bothering to monitor my temps.)

The researchers of this study found evidence suggesting the severity of circadian disruption may be linked to the severity of pregnancy disruption: mice subjected to advances of the light-dark circle had greater circadian clock disruption and lower reproductive success.  This group’s pregnancy success rate was only 22% compared with the control group of 90%.

WOAH. That’s quite a difference!

So what does this mean?  This means that if this affects mice, there is a good chance it affects humans too – but to what extent remains unknown, more research is needed before conclusions can be made confidently. ….but I couldn’t find anything taking this research further forward.

Now, there have also been a large survey study of flight attendants to examine fertility….there are two interesting conclusions, first that flight crew were found to be more likely to suffer from irregular periods, and also more likely to suffer a miscarriage.  But I find the study designs less compelling, so I’m not even going to write about this in much detail (but you can judge for yourself here).

So is there something that can be done to prevent suffering from the effects of flying and jet lag?  No one knows for sure, but we do know that Melatonin is an important hormone that regulates other hormones…this can be taken as a supplement, but it can also have negative effects on fertility too when taken as a supplement.  And this is what I will talk about in some more detail in Part 2 later this weekend!

[1]  Summa KC, Vitaterna MH, Turek FW (2012) Environmental Perturbation of the Circadian Clock Disrupts Pregnancy in the Mouse. PLoS ONE 7(5)

[2] Circadian rhythms fact sheet on the National Institute for General Medical Sciences website