If I had a nickel for every time I heard a mom say, "I would love to have a doula, but my husband [or partner, or mom, or whoever is going to be the primary support person] is against it" - well, I would be a much richer doula! In these situations, unfortunately, their support person's opposition usually wins out over mom's desire for a doula - and more unfortunately, I sometimes hear mom saying later that she regrets letting herself be overruled.
Much of the resistance seems to be based in the idea that the doula will take over the family's role. I think they envision the doula hovering around mom - getting her everything she needs, rubbing her back, talking with her - while her family sits in the corner watching, excluded from being hands-on.
What I try to express to people who envision that is that this is almost NEVER the picture you truly see at a doula-assisted birth - instead, it's what I see happening when I first walk in the room! Mom is often lying in bed, and her family/friends are lined up on the couch watching her like a TV show, wanting to help but not sure what to do; or slightly better, standing next to her as she vocalizes through a contraction but not sure what to say or how to help.
My goal is to change that picture, but not in the way the family is envisioning. In fact, my ideal picture is for the people who love the laboring woman the most to be the ones who are massaging her lower back, who are whispering encouragement in her ear, who she leans on during a contraction; if there's anyone sitting on the couch watching, it's me!
To get to this picture, there are a few key things I do as a doula that I think are so important: first, I help the support people understand what's normal. They may be very anxious about noises mom is making, or the length of labor, or baby's heartrate. I can help them understand that things are going normally, which gives them the space and confidence to reassure the laboring woman and keep her going. It sounds simple, but I think it's absolutely one of the most important things I do. You can watch a dozen birth videos and still find the actual process and presence of labor intimidating; it takes a little while to get comfortable with its rhythms and sounds and, ahem, bodily fluids. Just having a calm, confident presence frees up so much energy that is otherwise in anxiety and helps everyone enjoy the birth experience without fear.
Second, I know the ins and outs of the labor room. I know where the volume control is on the fetal monitor (and that it's perfectly fine to turn it down), where to find the birth balls (and how to get mom onto one without disturbing the monitors and IVs if she can't get them disconnected), how long that fetal monitor really needs to run before she can take it off and start intermittent monitoring (and I'll happily be the one to push the call button and ask the nurse to come in and take mom off).
Third, I remind and reinforce what they may already know. For example, I find more and more that there's some point in labor where I sense that mom needs to get in the tub or shower. She's starting to get totally overwhelmed and I can see incipient panic in the eyes of her support team. Sure, they learned that water can be helpful in labor; it's probably on their birth plan. But in the moment, they just don't think of it. Often, mom is reluctant to try it (remember, she's totally overwhelmed and even walking one step seems impossible), but I encourage her, get the tub all set up, she decides to give it a shot, and... aaaah. She relaxes into the water and gets her second wind. The bathroom is tiny, so her partner kneels by the tub to coach her through contractions and I retreat into the L&D room to just listen in case they need anything. This is often when mom is going through transition and I love getting to facilitate those last intimate moments between the parents before she starts to push and they get ready to meet their baby.
Finally, while I'm happy to sit on the couch and hang out if that's all that's needed, I should add I don't need to be hands-on to be busy as a doula! I can be running down the hall for more ice or to heat up the rice pack or getting snacks for mom/support people; bringing fresh washcloths for mom's forehead; catching medical staff at the door so if they've just come to "check in" I can update them without them having to interrupt the laboring woman's space; searching out birth balls, rocking chairs, squat bars, etc.; plugging and unplugging portable IVs, fetal monitors, etc. if mom is moving around/headed to the bathroom; and on and on. Again, these are things that the other support people might be hesitant to do or not know their way around well enough to do confidently; I can take care of that stuff and free the family up for focusing on mom and baby.
In short, a doula does not and cannot replace a woman's own family and friends - and doesn't want to! She is there to make everyone's experience better. Once your support team understands this, they're usually much more open to having a doula at the birth.
You could also try this quote on them, from an OB-GYN who had a doula at her first birth: "I can't say if having a doula shortened my labor, but it definitely lengthened my marriage!"
Do you have family and/or friends who are planning to be at your birth, but are resistant to the idea of a doula? Here are a few things for them to read to get educated about a doula's role at a birth:
From DONA: http://www.dona.org/PDF/DadsandDoulas.pdf
From Penny Simkin, doula extraordinaire: Myths about Dads and Doulas
Written by a dad: 5 Reasons Dads Should Demand a Doula
Do Doulas Replace Dads? includes a nice chart on what kind of support each person in the birthing room provides, and where doulas do and don't overlap.
(I apologize for the heteronormativity of all these links! I have tried in this post to use language that's inclusive of different types of family structures. Hopefully regardless of what label your support people fall under, they can find this information helpful.)
In the end, remind yourself and your support people - this is YOUR birth. Just as you have the right to say that no, your mother-in-law and all your second cousins are NOT welcome in the delivery room - you have the right to say that you WOULD like a doula there. If this is truly important to you, your support people should respect that and work with you to find a doula they feel confident will empower them, and you, during the birth.