Anything you do requires preparation, then why not for Labor / delivering a baby..?
Practicing yoga during your pregnancy is very important; it keeps you and your bundle of joy healthy and active. Yoga also helps to support Mom-to-be emotionally and physically strong.
Start your Prenatal yoga at the end of your Third Trimester, as initial months fetus will be still growing and the risk of miscarriages will be high.
Lots of Pranayama / Breathing exercises and Meditation will help your body, mind and soul to manage stress levels. Along with some Asanas as below will increase your stamina to bare labor contractions.
Virabhadrasana II (Warrior II Pose)
Squats with Support
Cat and Cow
Finally complete with Savasana (Corpse Pose) – Preferably Side Lying for 05 minutes for relaxation.