Preventing Postpartum Depression: A Dyadic Approach Adjunctive to Obstetric Care
Phase: NA
Conditions: Postpartum Depression (PPD)
Sponsor: Columbia University

 
 
 
 
 
 
Preventing Postpartum Depression: A Dyadic Approach Adjunctive to Obstetric Care 
 
 
 
NCT03283254 
November 12, 2024 
 
 
 

STUDY PROTOCOL 
 
CONSENT: 
Consent is obtained by those study staff with a Bachelor's degree or higher, who passed all 
necessary CITI training, and are IRB-approved to obtain consent. A link to the consent form is 
sent to the participant prior to the consent session. Consent forms are either signed in-person on 
paper copies or are signed electronically via REDCap by both the potential participant and the 
research staff obtaining consent. Potential participants are emailed the link to the electronic 
consent form prior to the virtual consent session, which they can access with any device that can 
connect to the internet. The Redcap consenting record is updated to contain the most recent IRB-
approved and stamped Consent and HIPAA forms. All potential participants are asked if they 
give additional, optional consent to have their participation in the study filmed for use in front of 
a professional audience. If participants give consent to be filmed, they are provided with an 
additional consent form addendum. An informed Consent Form is sent via an alert which is 
logged, time-stamped & encrypted when the "protect mode" is turned on. The risks related to a 
loss of confidentiality when using electronic devices to transmit, store, and/or access the Consent 
Form and HIPAA forms are outlined in the Consent Form and discussed during the consent 
process. Additionally, the possibility that data could be accessed by others, should the participant 
lose their electronic device, lend the device to other people, or if the device is subject to a search 
warrant or subpoena, is described to the participant during the consenting session. All 
participants who sign via REDCAp, are offered the option to receive the consent and HIPAA 
forms as hard copies via the mail if requested. 
 
SCREENING 
PHASE 1 OF SCREENING 
Phase 1 of screening is conducted via telephone by a CITI trained research assistant to determine 
if participants meet the initial inclusion and exclusion criteria listed below. The results are 
entered in REDCap, an online secure database. All information entered in Redcap is de-
identified using a screen ID. Any identifying information is entered in a password-protected 
Excel document on our server.  
 

Inclusion and Exclusion Criteria: Participants are screened at 20-29 weeks gestation 
Inclusion: 
1. Healthy pregnant women between 18-45 years old [phone screen, self report]: 
2. A healthy, singleton pregnancy [phone screen, self report] 
3. Fluent English speaker [phone screen, self report] 
4. Receiving standard prenatal care [phone screen, self report] 
5. A score of 19 or greater on the Predictive Index of Postnatal Depression (PIPD), indicating 
risk for developing postpartum depression; or score of 7 or greater on the Edinburgh Postnatal 
Depression Scale (EPDS). [phone screen, assessment administered by trained staff] 
 
Exclusion: 
1. Multi-fetal pregnancy [phone screen, self report] 
2. Illicit drug use, alcohol use during pregnancy [phone screen, self report] 
3. Acute medical illness or significant pregnancy complication [phone screen, self report] 
4. Currently in weekly, individual psychotherapy, including psychopharmacology [phone screen, 
self report] 
5. Psychotic d/o; Bipolar I; Major Depressive Disorder [phone screen, MINI assessment and 
clinical interview administered by trained clinicians] (Determined in Phase 2 of Screening) 
 
If eligible based on the initial phone screen, participants are asked to participate in a follow-up 
screening session, either by telephone or via HIPAA compliant video call to assess the final IRB 
approved exclusion Criteria (which are determined by the clinical interview and MINI 
assessment, which is administered by a licensed clinician or an unlicensed clinician under 
licensed supervision. 
 
PHASE 2 OF SCREENING 
The potential participant is first consented for this screening session. If consented, the potential 
participant undergoes a screening conducted by both the research assistant and a licensed 
clinician or an unlicensed clinician under licensed supervision. 
The potential participant then meets virtually with a licensed clinician or an unlicensed clinician 
under licensed supervision who conducts a clinical interview and a standardized assessment 

(MINI) to screen for psychosis, major depressive disorder, and bipolar disorder. Participants that 
meet criteria for any of those disorders are not enrolled in the study, but the clinician is to 
proceed by: (1) making an immediate appropriate referral, or (2) arranging for an immediate 
psychiatric evaluation. 
Information collected during the screening procedure was used to confirm eligibility based on 
the IRB approved inclusion and exclusion criteria. The screening and the screening results were 
reviewed and approved by the PI. 
 
Baseline Assessment (20-29 weeks gestation): 
A trained research worker will administer the Hamilton Anxiety Scale (HAM-A) and Hamilton 
Depression Scale (HAM-D) to the participant. 
 
Prenatal Session 1 (28-32 weeks gestation) 
At this time point, if the individual agrees to participate in this session and gives consent, the 
individual is randomly assigned to one of two groups: Intervention vs. Enhanced Treatment As 
Usual (ETAU). When the participants are 28-32 weeks pregnant, they participate in an in-person 
session (pre-COVID) or in a virtual session (during COVID), either by phone or video call, and 
are asked to complete mood assessments, a cognitive assessments and answer questionnaires 
about feelings, life events, and sleep. Participants are asked a questionnaire about the effect of 
COVID-19 on their lives. In total, these questionnaires take about 90 minutes. All questionnaire 
results are entered in Redcap, an online secure database. All information entered in REDCap is 
de-identified using a screen ID. At home, we ask participants to wear an activity monitor for 7 
full 24-hour days. We ask participants to complete a sleep diary noting sleep times and durations 
for the seven consecutive days they are wearing the activity monitor. 
 
Prenatal Session 2 (34-39 weeks) 
At 34-39 weeks gestation, participants have another session (in-person if pre-COVID or virtual if 
during COVID), and complete mood assessments, a cognitive assessment, and answer more 
questions about feelings and sleep. This session takes about 75 minutes. They are asked to wear 
the activity monitor again for 7 days and complete a sleep diary (5-10 minutes to complete). 
 

All participants are provided with psychoeducation (and an information sheet) that highlights the 
warning signs of depression and the risks of depression and contact information for research staff 
so that they can access help and referrals if they begin to experience depression. All participants 
(regardless of group assignment) are encouraged to contact the study clinician at any point 
during the study if they are interested in a referral for treatment. 
 
Newborn Session (18-36 hours post-delivery) 
Participants  are invited to have their newborn participate in an EEG sleep study that occurs 
between 18-36 hours after birth in the newborn nursery. We will examine variation in EEG 
left/right power asymmetry in relation to potential group differences in the effectiveness of the 
intervention in helping mothers function as a social "buffer" and modulate infant reactivity. The 
newborn EEG sleep protocol takes place in the newborn nursery while the baby is sleeping. This 
is a non-clinical EEG recording. A cap with EEG sensors is placed on the newborn’s head by a 
trained member of the research team. The research team then waits for the baby to enter a state 
of quiet sleep. This allows the research team time to measure brain activity while the baby 
sleeps. The participant is reassured by the research team that although the sensors  may leave a 
slight red mark for a brief time after they are removed, this procedure is completely painless and 
does not harm the newborn. 
 
The EEG session takes approximately 30 minutes. This session is video recorded to allow the 
researchers to collect information about newborn behavior during the session. In total, including 
setup of materials and video-recording, the session is approximately 1.5 hours in duration. 
 
The participant is allowed extra time to pick up, feed, comfort, or change the newborn to 
accommodate fussiness or discomfort at any time during the EEG. If the participant is 
uncomfortable with the EEG, they were free to stop the session. 
 
If the participant gives birth prior to 37 weeks, they do not complete this EEG session with their 
newborn. The participant is still be able to proceed with the rest of the study. Participants did not 
complete this session during the COVID pandemic. 
 

6-Week Postpartum Session 
At 6 weeks postpartum, participants are asked to participate in another session (in-person if pre-
COVID or virtual if during COVID), to complete mood assessments. This session is about an 
hour. During this session, participants are videotaped as they engage in a standard routine of 
infant care. This takes about 5 minutes to complete. 
 
If the session is completed in-person (not virtually), participants are invited to complete the 
infant EEG. We will examine variation in EEG left/right power asymmetry in relation to 
potential group differences in the effectiveness of the intervention in helping mothers function as 
a social "buffer" and modulate infant reactivity. The 6-week postpartum EEG sleep protocol 
takes place while the baby is sleeping. This is a non-clinical EEG recording. A cap with EEG 
sensors is placed on the newborn’s head by a trained member of the research team. The research 
team then waits for the baby to enter a state of quiet sleep. This allows the research team time to 
measure brain activity while the baby sleeps. The participant is reassured by the research team 
that although the sensors might may leave a red mark briefly after they are removed, this 
procedure is completely painless and does not harm the newborn. 
 
The EEG session takes approximately 30 minutes. This session is video recorded to allow the 
researchers to collect information about infant behavior during the session. In total, including 
setup of materials and video-recording, the 6-week EEG session is approximately 1.5 hours in 
duration. 
 
The participant is allowed extra time to pick up, feed, comfort, or change the infant to 
accommodate fussiness or discomfort at any time during the EEG. If the participant is 
uncomfortable with the EEG, they are free to stop the session. 
 
Participants wear an activity monitor again for 7 full days. While wearing the monitors, 
participants complete a sleep diary noting sleep times and durations, which takes about 5-10 
minutes.  Participants in the treatment group are asked to complete a diary entry that asks them 
the frequency and duration of their utilization of the skills learned from PREPP (i.e., 
carrying/holding baby, accentuation of day/night cues, focal feeding, use of swaddling, 

mindfulness techniques). These questions take about 10 minutes to complete. Infant sleep is 
assessed using a Smart Sleep Sensor worn by the infant. The Sensor detects day and night sleep 
activity by recording activity patterns during the time intervals in which it is worn. Infants wear 
the Sensor for four days (24- hour periods). 
12-Week Phone Session 
At 12 weeks postpartum, participants complete mood assessments over the phone. This takes 
about an hour to complete. 
16-Week Postpartum Session 
At 16 weeks postpartum, participants are asked to participate in a final session (in-person if pre-
COVID or virtual if during COVID) to complete mood assessments and other questions related 
to feelings, life events, and sleep. Participants are asked again to complete a questionnaire about 
the effect of COVID-19 on their lives (if during COVID pandemic). 
All together, these questionnaires take an hour to complete. Participants are asked to sit on the 
floor and play with their baby using a set of toys they usually use at home. They are asked to 
engage in free play for 10 minutes, and their play interaction is videorecorded and later coded 
using the Emotional Availability (EA) Scales. Mothers and infants are also asked to participate 
in a modified 'double' Still Face Protocol (SFP), an A-B-A-B-A design with alternating free-play 
(A) and still-face (B) periods. The entire SFP session is videotaped for later behavioral coding. 
The session begins with five minutes of face-to-face free play, followed by a two-minute still-
face episode. Two additional free-play periods and a second still-face episode, each lasting two 
minutes, follows. A study coordinator signals transitions by saying "Switch". If the infant cries 
for more than 30 seconds or intensely for over five seconds, the session is stopped so the mother 
can comfort the infant. The full procedure lasts about 20 minutes. Frequency of infant positive 
affect, signs of avoidance (infant head turn and back arch), and duration of infant distress/crying 
and neutral/positive vocalizations will be coded. Mothers will be coded for duration of 
vocalizations to the infant, touching the infant, and positive/negative affect. 
 
During this session, participants are also videotaped as they engage in a standard routine of 
infant care. This takes about 5 minutes to complete. 
 

For a final time, participants wear the activity monitor again for 7 days. Participants complete a 
sleep diary noting sleep times and durations, which takes them 5-10 minutes to complete. 
Participants in the treatment group complete a diary entry asking them about the frequency and 
duration of their utilization of PREPP skills. Infant sleep is assessed using a Smart Sleep Sensor 
worn by the infant. The Sensor detects day and night sleep activity by recording activity patterns 
during the time intervals in which it is worn. Infants wear the Sensor for four days (24- hour 
periods). 
Table 
Session 
Task 
Time Commitment 
Prenatal: 28-32 weeks 
Questions about mood and COVID-19, cognitive assessment 
90 minutes 
Prenatal: 34-39 weeks 
Questions about mood, cognitive assessment 
75 minutes 
Newborn: 18-36 hours 
Infant EEG 
1.5 hours 
Postpartum: 6 weeks 
Questions about mood, cognitive assessment, infant care 
routine, Infant EEG 
2.5 hours 
Postpartum: 12 weeks 
(on the phone) 
Questions about mood and cognitive assessment 
60 minutes 
Postpartum: 16 weeks 
Questions about mood and COVID-19, cognitive assessment, 
Infant care routine, Mom/Baby play 
2.5 hours 
 
Baby Day Diaries 
At 6 and 16 weeks postpartum, mothers are asked to complete four consecutive days of 24-hour 
diaries describing infant and parental behavior (the Baby Day Diary). The diaries allow for 
notation of infant cry, fuss, and awake-content, feeding and sleeping activity. Caregiving 
behavior is also noted, including; changing, bathing, dressing, holding/carrying and 
playing/talking behaviors as well as their own sleep periods. Baby diaries take about 30 minutes 
to complete. 
List of Instruments and Standardized Protocols: 
Data Collection Instrument 
Screening 
(20-29 weeks) 
Prenatal 1 
(28-32 weeks) 
Prenatal 2 
(34-39 weeks) Newborn 
6 
week 
12 
week 
16 
week 
Demographics 
 
X 
X 
 
X 
X 
X 
Newborn Delivery Data 
 
 
 
X 
 
 
 
Pregnancy Medical History 
X 
 
 
 
 
 
 

Predictive Index of Postnatal 
Depression (PIPD) 
X 
 
 
 
 
 
 
Mini International 
Neuropsychiatric Interview 
(MINI) 
X 
 
 
 
 
 
 
Columbia Suicide Severity 
Rating Scale (C-SSRS) 
X 
X 
X 
 
X 
X 
X 
Edinburgh Postnatal Depression Scale 
(EPDS) 
X 
X 
X 
 
X 
X 
X 
Hamilton Anxiety Scale (HRSA) 
X 
X 
X 
 
X 
X 
X 
Hamilton Depression Scale (HRSD) 
X 
X 
X 
 
X 
X 
X 
Personal Health Questionnaire-9 (PHQ-9) 
 
X 
X 
 
X 
X 
X 
Pittsburgh Sleep Quality Index (PSQI) 
 
X 
X 
 
X 
X 
X 
Pregnancy Physical Activity 
Questionnaire (PPAQ) 
 
X 
X 
 
 
 
 
Family History Screen (FHS) 
 
 
X 
 
 
 
 
Adverse Childhood Experiences 
Questionnaire (ACE) 
 
X 
 
 
 
 
 
Benevolent Childhood Experiences scale 
(BCEs) 
 
X 
 
 
 
 
 
The Hunger Vital Sign (HVS) 
 
X 
X 
 
X 
 
X 
Experiences in Close Relationships (ECR) 
 
X 
 
 
 
 
 
Childhood Trauma Questionnaire (CTQ) 
 
X 
 
 
 
 
 
Multidimensional Scale of Perceived 
Social Support Questionnaire (MSPSS) 
 
X 
 
 
X 
 
 
Maternal Antenatal Attachment Scale 
(MAAS) 
 
 
X 
 
 
 
 
Abbreviated Brief Infant Sleep 
Questionnaire (BISQ) 
 
 
 
 
X 
 
X 
Childcare Arrangement Scale (CAS) 
 
 
 
 
X 
 
X 
Infant Intentionality Questionnaire (IIQ) 
 
 
 
 
X 
 
X 
Infant Nutrition Questionnaire (INQ) 
 
 
 
 
X 
 
X 
Karitane Parenting Confidence Scale 
(KPCS) 
 
 
 
 
X 
 
X 
Short Acculturation Scale for Hispanics 
(SASH) 
 
 
X 
 
 
 
 
Experiences of Discrimination (EOD) 
 
 
X 
 
 
 
 

Adult Attachment Questionnaire (AAQ) 
 
X 
X 
 
 
 
 
Maternal Postnatal Attachment Scale 
(MPAS) 
 
 
 
 
X 
 
X 
Being a Mother (BaM-13) 
 
 
 
 
 
 
X 
Parental Bonding Instrument for Mothers 
(PBI-M) 
 
X 
X 
 
 
 
 
Parental Bonding Instrument for Fathers 
(PBI-F) 
 
X 
X 
 
 
 
 
Rejection Sensitivity Questionnaire (RSQ) 
 
X 
 
 
 
 
 
Difficulties in Emotion Regulation Scale 
(DERS) 
 
X 
X 
 
X 
 
 
Interpersonal Support Evaluation List 
(ISEL) 
 
X 
 
 
 
 
 
COVID-19 Questionnaire 
 
X 
 
 
 
 
X 
Utilization of PREPP Skills 
 
X 
X 
 
X 
 
X 
Infant EEG 
 
 
 
X 
X 
 
 
Adult Activity Monitor 
 
X 
X 
 
X 
 
X 
Sleep Log 
 
X 
X 
 
X 
 
X 
Infant Smart Sleep Sensor 
 
 
 
 
X 
 
X 
Baby Day Diary 
 
 
 
 
X 
 
X 
Infant Care Routine, video 
 
 
 
 
X 
 
X 
Modified 'double' Still Face Protocol, video 
(SFP) 
 
 
 
 
 
 
X 
Free Play, Video 
 
 
 
 
 
 
X 
 
 
Treatment Protocols: 
Experimental Arm: PREPP Intervention 
The intervention is carried out at 5 timepoints, Session 1 at 28-32 gestational weeks, Session 2 at 
34-39 gestational weeks, Session 3 at 6 weeks postpartum, Check-In Session 1 within 3 days of 
the birth and at Check 2 Session at 2 weeks postpartum. These sessions are scheduled to coincide 
with standard medical visits (3rd trimester ultrasounds and 6-Week Well Baby visit), which 
enable us to test the feasibility of incorporating these sessions into routine medical care. A 
licensed trained clinician or an unlicensed trained clinician under licensed supervision provide 
the intervention. The sessions of this preventive psychotherapy are comprised of three 

components: (a) mindfulness and self-reflection skills, (b) parenting skills and (c)psycho-
education. The intervention protocol encompasses the following 5 specific established behavioral 
techniques: (1) feeding the infant between 10 pm and midnight, even if s/he must be awakened 
(‘a focal feed’); (2) accentuating differences between day and night cues so that there are higher 
levels of stimulation during the former than the latter; (3) assuming adequate weight gain is 
reached by 3 weeks, lengthening the latency to feeding time in the middle of the night by 
engaging in other attentive activities such as walking with the baby and diapering; the goal is to 
lengthen the nighttime feeding intervals by extinguishing the association between night time 
waking and feeding; (4) carrying infants for a minimum of 3 hours a day, throughout the day, 
independent of responding to crying, carrying during feeding, and whether the baby is awake; 
and (5) learning to swaddle the baby as a possible soothing intervention. Mindfulness-based tools 
are provided with the aim to (1) aid them to return to sleep after waking at night, (2) help them to 
cope better when their babies are distressed or unsoothable. These mindfulness exercises are 
provided as audio files via an App. 
 
Active Comparator: Enhanced Treatment As Usual (ETAU): 
ETAU comprises Postpartum Depression psychoeducation, mood assessments, and referral for 
treatment if needed or requested by the participant. Three sessions are delivered by licensed 
trained clinician or an unlicensed trained clinician under licensed supervision. Participants 
receive "usual care" along with Postpartum Depression psychoeducation and enhanced support 
for finding perinatal mental healthcare treatment when appropriate by meeting with a study 
clinician specifically assigned to provide ETAU in this study at three times that are aligned with 
PREPP sessions that span from pregnancy to 6 weeks postpartum. At the first contact, 
participants meet with their assigned ETAU clinician and are given information about PPD, a 
brief clinical mental health assessment, and a referral for treatment if warranted or requested; the 
second session is a follow-up mental health clinical assessment with the study clinician and a 
referral for treatment if warranted or requested; at the third session, participants meet again with 
their study clinician and receive a mental health assessment, review relevant psychoeducation on 
PPD and are referred to treatment when appropriate. 
 
Statistical Analysis Plan 

Overall. Based on preliminary data, we anticipate minimal attrition (≤5%) during the first two 
assessment sessions (pre-delivery), and up to 33% attrition postpartum across both groups in the 
worst-case scenario. All participants with data available for a given study phase (pre- or 
postpartum) will be included in the primary analyses. Before conducting hypothesis tests, we 
will screen all variables at all time points for out-of-range values, outliers, and data 
inconsistencies. Means, standard deviations, interquartile range, minima, and maxima for 
continuous variables and proportions for categorical variables will be reported. 
  
Following CONSORT guidelines, the primary analyses for all aims will follow an intention-to-
treat (ITT) approach, including all randomized participants regardless of treatment adherence or 
dropout. If significant imbalances in baseline covariates (e.g., maternal age, BMI, birth order, 
infant sex) are observed despite randomization, these variables will be included as covariates in 
the models. Additional exploratory models will examine relevant biological factors, such as 
maternal BMI, fetal/infant sex, maternal age, infant gestational age at birth, and birthweight 
corrected for birth age, as potential covariates. 
  
Aim 1. Reduce women’s distress during pregnancy. We hypothesize that PREPP will be 
associated with: (A) Diminished depressive symptoms using interviewer-rated and self-report 
questionnaires; (B) Improved perception of sleep quality relative to objective changes in sleep 
duration (per self report and actigraphy).  
  
Analysis for Aim 1A: For depressive symptom outcomes (HRSD, PHQ-9, HRSA, PSQI, 
EPDS), we will fit linear mixed-effects models with fixed effects for Treatment (PREPP vs. 
ETAU), Time (2nd and 3rd assessments), and birth order, along with subject-specific random 
intercepts. For EPDS, we will adjust for the screening score and test a Treatment × Screening 
Score interaction as a secondary analysis. Additional moderators will also be tested. 
Analysis for Aim 1B: Two ActiGraph-derived measures, total sleep time (TSTact) and sleep 
efficiency (SEact), will serve as outcomes in separate mixed-effects models with fixed effects for 
time and day (within the ActiGraph epoch) and subject-specific random intercepts, assuming an 
AR(1) correlation structure. We will assess whether adjustment for weekday/weekend is 
warranted. Subject-specific means of these measures will be used as predictors of their subjective 

counterparts (TSTact, SEact) in additional mixed models testing for treatment group differences 
in the association between objective and subjective sleep measures. Moderation by trauma 
history and attachment will be explored. 
  
Aim 2. Determine the maintenance of improved maternal mood and differences in infant 
behavior. We hypothesize that PREPP will be associated with: (A) Lower rates of PPD and 
distress, including poor sleep efficiency, assessed by interviewer-rated and self-report 
questionnaires as well as sleep actigraphy. (B) Less infant fuss/cry behavior and longer nocturnal 
sleep bouts based on maternal report and actigraphy.  
  
Analysis for Aim 2A:  Separate linear mixed-effects models will be used for each maternal 
mood outcome (PHQ-9, HRSD, EPDS, HRSA, PSQI) and ActiGraph-derived sleep measures. 
Models will include Treatment, Time (6, 12, and 16 weeks postpartum), and their interaction, 
with baseline (pregnancy) values as covariates. Subject-specific random intercepts will be 
included. The primary parameter of interest is the Treatment × Time interaction; if non-
significant, the main effect of Treatment will be tested. PPD diagnosis will be modeled using 
mixed-effects logistic regression with analogous fixed effects. 
For infant outcomes (6 and 16 weeks), linear mixed-effects models will assess Treatment effects 
without Time × Treatment interaction. Sleep data will be processed as in Aim 1B. Covariates 
include time-varying factors such as weaning, solid food introduction, maternal return to work, 
and social support. Moderators (infant sex, trauma history, attachment) will also be assessed. 
Analysis for Aim 2B:  Infant sleep and cry behavior  at 6 and 16 weeks will be compared using 
mixed-effects models with Treatment, Time, and their interaction as fixed effects. Covariates and 
secondary analyses will be same as those in Aim 2A. 
  
Aim 3. Identify some of the pathways by which PREPP positively affects the dyad. We 
hypothesize that PREPP-associated: (A) Lower depression scores postpartum will be mediated 
by concurrent and/or temporally earlier maternal reports of less infant fuss/cry behavior and 
higher parenting competence; (B) Less infant fuss/cry behavior will be mediated by fewer 
concurrent and/or temporally earlier negative infant attributions and higher concurrent observed 
maternal sensitivity; (C) More positive perceptions and objective assessments of maternal 

postpartum sleep efficiency will be mediated by greater infant left frontal EEG power reflecting 
sleep spindle activity and associated longer average durations of infant nocturnal sleep per 
maternal report and actigraphy.  
  
Analysis for Aim 3: Structural equation models will be used to test multiple-mediation. The 
mediation and Lavaan R packages will be used for this modeling as it can accommodate both 
continuous and ordered categorical (including dichotomous) variables. Indirect effects (i.e. 
combined mediational pathways) will be tested using the bootstrapping with 10000 resampling. 
Specifically for Aim 3A, we will test whether the effect of PREPP on maternal depressive 
symptoms at week 16 is mediated by infant fuss/cry behavior and higher parenting competence 
assessed at 6 and 16 weeks after delivery. A model without inclusion of week 16 mediators will 
also be considered (due to the contemporaneousness of week 16 with the outcome). For Aim 3B, 
the primary outcome is infant fuss/cry behavior at week 16 and mediators are the maternal 
reports of negative infant attribution assessed at 6 and 16 weeks after delivery and maternal 
sensitivity at week 16 after delivery. Because of the concurrently observed mediators and 
outcomes, alternative mediational pathways will be evaluated and compared. For Aim 3C, a 
mediation model with EEG power at week 6 and avg. infant sleep (actigraphy) quality will be 
assessed as mediators of the treatment effect on maternal sleep at week 16, controlling for EEG 
power at birth as a covariate.  
  
Power analysis We adjusted for multiple comparisons (five primary outcomes across Aims 1 and 
2) using Bonferroni correction, resulting in a significance threshold of 0.01. For Aim 1, with N = 
214 and an assumed 5% attrition, our mixed-effects model analysis is powered to detect a 
minimum effect size of d = 0.48 (assuming within-subject correlation r = 0.2). Prior research has 
shown larger effects (e.g., d = 0.85 for EPDS in mindfulness-based therapy), indicating our 
design has ample power. For Aim 2, assuming 33% attrition and five primary outcomes, power 
calculations show that N = 107 per group is sufficient to detect interactions as small as d = 0.087 
with 80% power at a Bonferroni-adjusted α = 0.01. Our preliminary data support this 
assumption. For Aim 3, based on tabulated recommendations 184 for sample sizes needed to test 
mediation effects, with N=142 completers (assuming 33% attrition for assessments), we have 
more than 80% power to detect a significant mediation effect with moderate effect sizes (d=0.54, 

r=0.26) of both paths (i.e. the paths from treatment to the mediator(s) and the mediator(s) to 
outcomes). Since the full sample (N = 214) will be used in mediation models, the actual power 
will exceed this estimate.