. >> reporter: on this day in early august, she was visiting jessica marshall, then 7 1/2 monthing pregnant her home in brooklyn. they discuss issues like prenatal health and a birth plan. >> if you can relax and go into this, you're not so afraid, you're not so tense. if you're tight and tense and worried, it slows it down. >> reporter: she isn't a doctor or midwife. she's what's known as a doula. that's ancient greek for a woman who serves. doulas support pregnant women before, during, and after childbirth. >> being a first-time mother, i really wanted to take advantage of all the information that i could. i know the doulas typically are very supportive of mothers' birth plans. i wanted a doula that was supportive of me having a natural birth. >> the doula serves the woman. we don't work for the hospital. we don't work for the birthing center. we don't work for the midwife. we work for the woman. >> reporter: the service is provided for free backed by the new york city's department of health. it's called the by my side birth support program. it's aimed at women living in low-income, large