We at Spinning Babies recommend beginning Daily Activities as you feel fit for simple activities.
We don't recommend "feeling the burn" but rather listening and respecting your changing body to feel the stretch. Moving through a pose slowly and holding it with good alignment is more important for supple flexibility.
If you like the social feeling of a video, even at home, Daily Essentials yoga routine is a real "feel good" stretch half-hour physically and in mood. Starting the daily routine of stretching with Sarah Longacre in the Daily Essentials video at about 20 weeks pregnant has been attributed to shorter births by the parents who use it everyday.
We expect to see baby's position be anterior at each appointment from 30 weeks on to birth (in general, I observe that a first time mom has spontaneous onset of labor between 41 weeks and 41 1/2 weeks).
The left occiput transverse or left occiput anterior position in the womb most usually allows baby to be curled up and aim the small, round crown of the head into the pelvis.
Unexpectedly, a baby may rarely change position quite late in pregnancy.
Long car ride? Nope. Not in this case.
Strange turning movement with a jolt (like golfing or softball or giving a chiropractic adjustment as opposed to receiving one)? No.
Could it be the umbilical cord? This is unlikely but possible. Correct for the other reasons and ask for medical (or midwifery) assessment of baby's heart rate. During birth the baby will be listened to for dips in the heart rate and if they match a particular pattern, it may be assumed to be due to a short or wrapped cord. Often when a provider doesn't know the answer they fill in the "blank" with umblical cord and only after the birth if the cord is seen to be wrapped or uniquely short can we confirm that the baby's lack of descent or rotation was due to the cord. We leave this question for that time.
Could there be a twist in the pelvic floor lower down that made baby turn as s/he dropped? This may not be known, but a Physicial Therapist, Pelvic Floor Specialist, professional bodyworker, Osteopath or Chiropractor MIGHT be able to assess this. If getting an assessment isn't practical, doing the corrective activities wouldn't be harmful if they actually weren't needed.
The answer is the same here as for most mysteries, add balance and go within.
More practical tips for parents coming!