My Experience of Running During Pregnancy: The First Trimester


Every pregnancy is different, every runner is different and there is no one size fits all.  I have many friends who have had very different experiences to me, from stopping running as soon as they found out they were pregnant, to running a half marathon in their 2nd trimester and running through to 36 weeks pregnant. During the Boston Marathon last year I ran with a woman for a few kilometres who was 17 weeks pregnant and on track for a sub 4 hour marathon! Then there are the elite runners who continue to train and compete throughout their pregnancies.  Throughout my experience I have learnt that people will be very quick to give you their opinions, the research is limited and only you truly know your body.


Running has been an important part of my life for over 20 years.  It is a passion that my husband and I share with many of our friends and our holiday planning often revolves around events.  We had discussed starting a family and decided that I was going to train for a marathon Personal Best (and Boston Qualifying time)  and then see what happened. I was very fortunate, I got my marathon PB (and BQ) and 2 months later found out I was pregnant. Unfortunately statics were not on my side and I had a miscarriage in the first trimester.

1 in 4 known pregnancies end in miscarriage and the actual miscarriage rate is higher as pregnancies will miscarry prior to a woman even realising she is pregnant.  Miscarriages occur for many reasons and it is usually something completely outside your control. It is very common, but still not widely discussed, so often women and couples are left grieving and with lots of unanswered questions.

One of my first thoughts was, did my running have anything to do with it?  Then my rational scientific brain took over and I realised that was highly unlikely.  I was aware of the Exercise in Pregnancy Guidelines set by The Royal Australian and New Zealand College of Obstetricians and Gynaecologists as it is something that I have advised my patients on, but I decided to revisit the guidelines and do some of my own research.

The guidelines state:

  • Women without contraindications should participate in regular aerobic exercise and strength training.  

  • There is no evidence that exercise during an uncomplicated pregnancy is detrimental to the woman or foetus.

The current physical activity recommendations for Australian adults (aged 18-64 years) is being active on most, preferably all days of the week, aiming to accumulate 150-300 minutes of moderate intensity activity, or 75-150 minutes of vigorous activity, or a combination of the two.  An additional 2 sessions of strength training should be undertaken.

The recommendations in pregnancy are to continue with your previous exercise routine, as per the guidelines, but to potentially reduce the intensity by monitoring heart rate and to discuss with your GP or Obstetrician. I discussed my running with my GP and Obstetrician and both were very supportive of my running and the health benefits it would have for me and a developing foetus.  They recommended I keep my runs to under an hour, avoid running in the heat and keep my running at an easy intensity.


I have now had 5 first trimester’s and have continued to run to varying levels throughout.  I backed off in the middle of summer to avoid overheating, altered my running frequency, reduced running duration and used a heart rate monitor.  By my 5th pregnancy I realised that miscarriage was out of my control, so if my body told me to run I would, and if my body told me to rest I would.  I listened to my body and ran at a comfortable pace, would walk when I needed to and just enjoy the experience.

As soon as I am pregnant running feels like harder work.  My easy running pace changes and hills become a challenge, but it is also the only time that I do not feel nauseous.  I feel great for a few hours after a run and can even stomach the idea of eating something.

My 5th pregnancy is being closely monitored with regular scans and already it looks as though Junior is going to be very active. Running helped me get through 4 miscarriages as it showed me that my body is a remarkable machine that will look after me, providing I look after it and not take it for granted.  Running gave me the opportunity to clear my head when I needed to and gave me something else to focus on.

Bring on the 2nd Trimester.