A doula, also known as a birth companion and post-birth supporter, is a non-medical person who assists a woman before, during, and/or after childbirth, as well as her spouse and/or family, by providing physical assistance and emotional support.
My Experience:
A doula is basically you and your partner's sidekick throughout your child's birth. Our doula Rylie (from http://www.newspiritarrivals.ca/) met with us to discuss about what to expect during pregnancy/birth and our birth plan/options. She demonstrated how I could massage Monica and discussed about what to expect as a father. Doulas encourage the natural birth method and helps your partner alleviate her pain during birth with several tools from using the Tens Unit, to massage, acupressure, aromatherapy, etc. I would highly recommend hiring a doula if your partner plans a natural birth. The doula is the first one to arrive on site when your partner feels contractions. They would be able to tell you if your partner's cervical dilation is 4 cms by the symptoms she is exhibiting. Keep in mind, your midwife or obstetrician will send you home from the hospital if your partner cervical dilation isn't at least 4 cm. Having a doula would save you the hassle and trouble of driving your partner to the hospital if she is not ready. Once your partner is in active labor it will increase to 7 cm. Full cervical dilation is when your partner's cervix measures 10 cms.
In general, if your partner plans to have a natural birth - Get a doula! She will thank-you in the long run. They're usually between $700-$1500 depending on what services you require. There is a free doula service at the South Community Birth Program (http://scbp.ca/doula-program) It is a great program if you don't care about who will be your doula on the day of your birth. Of course, you will still get to meet all of them during your appointments.