This is my unique experience. Yours will probably be totally different. Please get inspired by what you find here, however, listen to your body and do what feels right for you.
At first a little explanation:
I never practice during my period, I follow Nancy Gilgoff's advice and honour that time of month and take rest, do some restorative asanas, usually a yin yoga-type practice without the use of bandhas like Matthew Sweeney's Chandra Krama or Simha Krama (Moon and Lion Sequences).
In November 2014, I was heading to Petri Raisanen's 2nd series workshop to which I was very much looking forward. To my dismay I found out that my period was due exactly during his workshop. I decided to practice at least lightly because I didn't want to miss it. The workshop was intensive of course and I got a light period for a day only thinking it was the result of me practicing during my ladies' holidays.
We weren't exactly planning or trying super hard to conceive, we decided beginning of September that we might give it a go but because I lived in Brussels at that time and my partner in Bratislava, the first time we actually were together and the timing was right was on the 31st of October, which is ironically my birthday. I concieved on the first (albeit unintentional) attempt.
1st Trimester (1-14 weeks)
My doctor confirmed that I was pregnant during my yearly regular check-up when I was already in the 9th week of pregnancy. Before that I led a normal life, getting up in the morning to do my practice, then going to work or teaching, travelling, meeting friends for coffee or a drink etc. Thus, it didn't occur to me at all that I might be pregnant when for about two weeks I woke up extremely tired without any mood to practice asana. I did some pranayama and meditation and then barely made it to the bathroom and took a hot bath. When I managed to practice, I simply could not do Mayurasana, so I just skipped it and went on. I stopped craving coffee (that's when I started panicking!!!) and I had enough of wine after only one small glass at dinner.
So, I was taken aback when my doctor advised me to stop exercizing, flying and eating many many things. I decided to change my doctor because her orders seemed exaggerated and unfounded to me.
I decided to continue as before and do what feels right like skipping Mayurasana.
I travelled to my month-long yoga retreat with Petri Raisanen in Thailand, where I got up every morning at 4:30am, did my practice and then stayed in the shala for another 2 hours to assist Petri. When I had morning sickness, I did a special pranayama, which always worked within minutes. And luckily, I started craving coffee again, so life was good :)
Before conceiving, I practiced the whole primary and the whole intermediate series, alternating one day primary and the next intermediate, moreover I practiced Matthew Sweeney's Chandra Krama (Moon Sequence) and Simha Krama (Lion Sequence) during my period or moon days or on days when I did not manage ashtanga in the morning and had time in the evening. The reason being that I found ashtanga in the evenings to be too stimulating so I preferred a calming, grounding and soft practice for the evenings.
I got various advice from different teachers and from books, so I made my own combo. I felt good so I kept doing the entire primary series during the 1st trimester with all the twists but done loosely, jumps (when I had the energy) and the closing sequence with inversions and assisted dropbacks. I only cut down the length of headstand from my current 65 breaths to basic 15 breaths.
The main difference was my breathing which I always tried to keep calm in order not to overheat because by conceiving the body is already lightly overheated, so naturally my practice became softer but also longer. That was OK because there was nowhere to rush.
Apart from the breathing I focused on moving lightly and with ease into and out of each pose, I avoided all pushing and pulling, did things that felt good, stable and comfortable. My aim was to finish the asana practice feeling energized and not tired.
Naturally, intermediare series wasn't as straightforward. Peter Sanson advises women to stick to primary only, so I hesitated what to do and decided in the end to give it a go. Intermediate series was and still is more challenging than Primary so it was more tricky to keep my breath and energy level in check. I felt OK doing pashasana but because my feet weren't on the floor the pose was not stable enough so I rather started doing pashasana with feet apart binding around one leg only. As mentioned above, I avoided Mayurasana early on, but did everything up till Pincha Mayurasana. I skipped Karandavasana, Nakrasana, Vatayanasana (because this pose should be held with Uddiyana Bandha only) and Supta Urdhva Pada Vajrasana. I enjoyed doing Gomukhasana and Parighasana and the headstands but against the wall and with kicking up legs or bent legs up.
Oh, yes, I was happy to have an excuse and stop doing kapotasana :))
I stopped rechaka kumbaka (after exhalation), kapalabhati and bhastrika. Like asana, pranayama became much softer.
I kept doing nadi shodhana (alternate nostril breathing), viloma and analoma and the cooling sithali (I love the one with humming) is a must for every pregnant lady.
to be continued...