Inclusion criteria: participants were English-speaking nulliparous women with low-risk, healthy, singleton pregnancies in their third trimester who were planning a hospital birth and willing to be randomized. Exclusion criteria included high-risk pregnancy, extensive prior experience with meditation or yoga practice (brief prenatal yoga did not lead to exclusion), participation in other mind/body childbirth preparation courses (e.g., Hypnobirthing, Bradley Method), or planned Cesarean birth. In terms of race/ethnicity, the eligible, enrolled sample was 18% Latina/Hispanic (n = 5, missing = 1); 59% White (n = 17); 17% Asian (n = 5); 14% Multiracial (n = 4); 7% Black/African American (n = 2); 3% American Indian/Alaska Native (n = 1). More than half of the sample was below area median household income (n = 16, 55%); 10% reported household income < $10,000/year (n = 3). See Fig. 1 for the CONSORT flow chart of study participation.
Ethics approval and consent to participate
This study was approved by the University of California, San Francisco (UCSF) Committee for Human Research (Institutional Review Board). All participants gave signed informed consent for participation in research and provided signed Health Insurance Portability and Accountability Act of 1996 (HIPAA) authorization for complete medical record review.
First-time mothers in their third trimester of pregnancy were recruited to the study through provider referrals, as well as fliers and online parenting group recruitment advertisements with language targeting women with typical fears related to childbirth: e.g., “Are you worried about pain during labor?”. Initial eligibility screening was conducted by a brief online survey with follow-up by telephone to capture information related to each of the inclusion/exclusion criteria referenced above. We also collected information regarding intention to use epidural.
To minimize the probability of baseline group differences, randomization was stratified by pre-course intention to use epidural anesthesia and was performed with randomly varying blocks of 2 and 5 using a pre-programmed computer database. A UCSF senior biostatistician not affiliated with the study generated the randomization scheme. The study project manager (JGC) enrolled and consented study participants; group assignment and subsequent debriefing regarding intervention attendance was conducted by him opening a sealed envelope provided by the biostatistician. Data collection was completed online and through medical record review. The remaining study authors (including data analysts) were blinded to participant study condition.
As this was a small study with limited funding, we were constrained to a sample size of N = 30 that was selected a priori based on sample size recommendations for pilot trials (thus limiting our power to detect effects). Those assigned to the MIL group (n = 15) were given a space in a publicly available MIL workshop at UCSF during their third trimester. Tuition for MIL was paid for by the study. Participants assigned to the control condition (n = 15) were offered up to $200 USD tuition reimbursement for attending a study-approved, standard hospital- or community-based childbirth education course in the San Francisco Bay Area.
Self-report assessments were conducted at three time points: Time 1 (T1) = 3rd trimester baseline (immediately pre-intervention and pre-randomization) at average gestational age 29.4 weeks (standard deviation; SD = 3.64 weeks); Time 2 (T2) = in the week immediately following the intervention (post-intervention but prior to birth); and Time 3 (T3) at post-birth (postpartum) follow-up (conducted, on average, within six weeks after birth). In addition to providing childbirth education tuition, we offered incentive payments for each assessment (T1 = $40 USD; T2 = $50 USD; T3 = $60 USD), gradually increasing the amount offered to minimize study attrition. Data collection for this study was completed in 2014.
The mind in labor (MIL): working with pain in childbirth
MIL is a brief intervention for pregnant women and their partners specifically designed to target labor-related fear and pain by teaching tailored mindfulness-based coping strategies. It is a childbirth-specific, short form of the nine-week Mindfulness-Based Childbirth and Parenting program (MBCP)  adapted starting in 1998 from Mindfulness-Based Stress Reduction (MBSR) . The MIL course is delivered by professionally certified MBCP instructors and it is held over one weekend (Friday evening and all day Saturday and Sunday) for a total of 18 h of mindfulness training. Mindfulness strategies for coping with labor-related pain and fear are taught through interactive, experiential activities, with periods of didactic instruction.
In addition to standard childbirth preparation topics (i.e. birth physiology), the MIL program includes the following aims and learning objectives: 1) participants are guided to reframe childbirth pain as unpleasant physical sensations that come and go, moment by moment; 2) participants are taught how to uncouple the sensory component of pain from its cognitive and affective components, with the objective of decreasing fear and suffering related to the physical pain of childbirth; 3) participants learn how to be more aware of their own body and fearful reactivity to pain by practicing mindful coping with pain through a pain induction activity with ice; 4) pregnant women and their birth partners develop personalized strategies to best cope interpersonally and provide support to each other throughout the birth process.
To meet these objectives, instruction in formal mindfulness meditation are given during the workshop, including body scan, mindful movement/yoga, sitting and walking meditation, and mindful eating, as well as activities of daily living and pain coping strategies, such as mindfulness of breath, partner touch, body movement, and “sounding” (using low and/or loud vocal tones during periods of intense physical sensation). Additionally there is an inquiry practice between partners exploring fear in general and fear of childbirth in particular and specific mindfulness coping strategies for being with pain with an attitude of acceptance. Participants are provided with handouts and guided audio materials for optional practicing of mindfulness meditation and pain coping strategies at home. In the current study, the course developer (NB), a senior mindfulness teacher and certified nurse midwife, provided facilitation for all MIL intervention participants.
Active control condition: treatment as usual (TAU) standard childbirth education
Participants assigned to the TAU control condition were provided with a list of study-approved childbirth courses of comparable length and quality to the MIL intervention, but without any mindfulness meditation, mindful movement/yoga, or other core mind/body component (e.g., hypnosis). To form the approved list, we conducted a web search of available San Francisco Bay Area childbirth preparation courses then followed up with direct contact with providers to determine specific content regarding any topics related to mind/body health or stress reduction. If a control group participant could not find a pre-approved course convenient to their location and schedule, we offered to screen their preferred course. In this way, our list of approved courses grew as participants informed us of additional childbirth preparation programs. TAU control participants were strongly encouraged to participate in the control childbirth education with a partner or support person, just as with MIL. In the current study, n = 12 of the control participants reported that their partner or spouse attended the course with them.
Eligibility screening and all assessments were administered online via the Internet application, SurveyGizmo . The time points when they were administered to collect data for the current study is noted in parentheses.
Childbirth self-efficacy (T1, T2)
Childbirth self-efficacy was assessed with the Childbirth Self-Efficacy Inventory (CBSEI; α = .90) . The self-efficacy expectancy items rate how confident respondents feel in their ability to use the behaviors during labor and birth (1 = Not at all sure to 10 = Completely sure).
Maladaptive pain appraisal (T1, T2)
Maladaptive pain appraisal was assessed with the Pain Catastrophizing Scale (PCS; α = .92) . Respondents were asked to reflect on past experiences of physical pain and to rate the degree to which they experience particular thoughts and feelings (e.g., “It’s awful and I feel that it overwhelms me” on a scale of 0 (Not at all) to 4 (All the time).
Perceived pain in labor (T3)
The Visual Analog Scale (VAS)  was used to assess perceived labor pain. Participants were asked to retrospectively mark the level of pain they felt for each stage of labor on a 10 cm line representing a continuum of “no pain” to “worst possible pain.” The VAS is one of the most commonly used pain measures and it has been used successfully to assess labor pain . Participants rated their experiences of pain on the VAS during early labor (until 3–4 cm dilation), during active labor (from 4 cm to pushing), during pushing until birth, and from birth of the baby to delivery of the placenta.
Use of pain medication in labor
Use of pain medication in labor was ascertained from medical record review. Epidural/spinal anesthesia and opioid analgesia were coded as dichotomous variables. Use of opioid analgesia was endorsed if any systemic opioid narcotic (e.g., fentanyl, morphine) was administered at any point during labor (before birth), independent of epidural/spinal anesthesia.
A modified 24-item version of the Wijma Delivery Expectancy/Experience Questionnaire (W-DEQ; α = .94)  was used (T1 - T3) to gauge satisfaction with the birth experience (e.g., : “How happy were you in general during the labor and delivery?”) controlling for W-DEQ expectancies captured prior to labor and delivery. Items were rated on an intensity scale from 1 = Extremely to 6 = Not at all, and response options are customized for each item (e.g., 1 = Extremely happy to 6 = Not at all happy). Minor modifications to the scale were made in consultation with obstetric experts on the study team to enhance interpretability and cultural sensitivity of the terminology (e.g., we removed the item asking whether participants imagined they would feel “funny, natural, self-evident, or dangerous” at the time of delivery).
Additionally, we asked respondents to rate their satisfaction with their overall birth experience (T3), as well as with the care they received from healthcare providers during the labor and delivery (T3), on a scale of 1 – 10, with 1 = Not at all satisfied and 10 = Completely satisfied.
The 20-item Center for Epidemiologic Studies Depression Scale (CES-D; Cronbach’s α ranging from .85 to .90)  was used to measure depression symptoms (T1 - T3). The CES-D is widely used and is recognized to be reliable and valid. A score ≥ 16 is the clinical cutoff indicating risk of clinical depression.
Mindfulness and mindful body awareness
The Five Facet Mindfulness Questionnaire (FFMQ)  was used to assess levels of dispositional mindfulness (a tendency to avoid mindlessness in everyday life) at each time point (T1 - T3). The FFMQ consists of 39 items, yielding subscale scores that measure five elements of mindfulness (observing, describing, acting with awareness, nonjudging of inner experience, and non-reactivity to inner experience; Cronbach’s α ranging from .75 to .91).
The Multidimensional Assessment of Interoceptive Awareness (MAIA)  was used (T1, T2) to assess body awareness, which may be an important dimension of mindfulness  and particularly relevant for women preparing for childbirth. The MAIA consists of 32 items and measures eight dimensions of interoceptive awareness (noticing, distracting, worrying, attention regulation, emotional awareness, self-regulation, body listening, and trusting; Cronbach’s α ranging from .66 to .87).