Table 3.

Factors Influencing Treatment Acceptability, Access and Administration, and Adherence to 17-Alpha-Hydroxyprogesterone Caproate Therapy

Theme	Subtheme	Exemplary quote
Acceptability
Personal experience (patients and providers)	Motivation for a healthy baby	Patient: “Baby always come first, sometimes, you have to make sacrifices as parents and do things to our body that we don't want to do to have a healthy baby. If my doctor was to tell me to keep doing it, I would. Do I like it? No. Is it a sacrifice? Yes.”
		Maternal–fetal medicine physician: “I think that some patients are very willing to do it because they understand the risks associated with pre-term delivery. And I think that some patients understand the risks associated but it's not something that they necessarily want to commit to because they realize that it's going to be weekly injections.”
	Prior preterm birth experience	Patient: “… She was so tiny. So I didn't like that…I was so scared. I was so scared. I don't know, I just didn't like it… it was so stressful. So I was like, “Okay, yeah, I'll take [the injections]. Let's go to full term.”
	Clinical experience and practice	Nurse practitioner: “I've been in obstetrics since 1990, when it first came on the market I've had patients who have had four or five pre-term deliveries, and their first pregnancy with [17OHPC] going post term, which is phenomenal. I've seen first hand patients who have had really bad outcomes, that have now gone to full-term and post date.”
		Maternal–fetal medicine physician: “…when I first started, it was 17OHPC is the standard. This is what we have evidence on, and this is what we recommend, but now we present more options to patients and people seem to have a bit more opinions about it and I think when offered, the option of a weekly injection versus a vaginal suppository is often less appealing to patients.”
Influence of patient–provider communication (patients)		Patient who declined treatment: “It wasn't convincing and it just didn't sit right with me... [There could have been] more about it. They didn't really to me give... I asked… do y'all have any paper or pamphlet on it? And they didn't really give me anything like that. They just said basically there wasn't no harm so. Maybe one out of three or something woman may have a preterm labor. Just wasn't enough.”
		Patient who accepted treatment: “Yea, I was very skeptical because I was like, ‘It's shots and it's medicine, I don't know what it is,’ and stuff like that, but they talked to me about everything, so I got accepting to it. And then I started getting the shots.”
Access and administration
Coordination of services (e.g., pharmacy, insurance, home health agencies) (patients and providers)	Patient support	Patient: “… Everything went smoothly. I think they told me about it, someone reached out to me within a couple days, next thing I know my insurance company was calling me. Then [the home health company] was calling me like, ‘They'll be out Saturday.’ The pharmacy, everyone was pretty much in line, so it was pretty smooth.”
	Administrative burden for providers	Nurse practitioner: “I think what happens with some of the barriers for 17OHPC with the managed care companies for the Medicaid population, it varies that some require prior authorization, some do not. It can delay the administration. There are often times when one is delayed with getting the prior authorization, then the nurse has to call. That may take a couple days… sometimes it's declined. Then they have to call back and fight for it.”
Adherence
Expectations and management of painful side effects (patients)	Feeling unprepared	Patient: “Well, when the nurse came out, she said, ‘It's going to burn a little bit. It's gonna be like a little bee sting.’ That's not what it was. That's not what it was.”
	Resilience	Patient: “It got less intense at the end. But it's a needle, you know. The location was just itchy, sore lumps... I just tried to get past all that. It was like, anything to get me a full term baby so I just did it like that. It's just the soreness and the itchiness was the headache. It never made me like, I don't want to do it anymore. But I definitely couldn't wait to stop.”
Social adversity as barrier (providers)		Maternal fetal medicine physician: “…. I think the population of patients who are on medical assistance can sometimes not have great … they might not always have the best access to a phone that's always working or their number may change a lot, or they may have housing instability, so I think that that is a challenge too for them, or some of our patients are living in shelters or have a history of drug use or something like that, and I think that all of those things best contribute to difficulty with them accessing this care for sure”