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Duration of mother's milk expression
Time frame: From NICU admission through to 12 months postpartum
Months of milk expression via direct breastfeeding or pumping.
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Gestational weight-for-age
Time frame: Extracted from medical records 1-2 weeks after discharge from the NICU
Change in sex-specific gestational weight-for-age z-score while admitted to the NICU.
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Gestational length-for-age z-score
Time frame: Extracted from medical records 1-2 weeks after discharge from the NICU
Change in sex-specific gestational length-for-age z-score while admitted to the NICU.
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Gestational head circumference
Time frame: Extracted from medical records 1-2 weeks after discharge from the NICU
Change in sex-specific gestational head circumference z-score while admitted to the NICU.
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Necrotizing enterocolitis (NEC)
Time frame: Extracted from medical records 1-2 weeks after discharge from the NICU
Experienced NEC during NICU stay according to Vermont Oxford Network (VON) definition; criteria: yes/no.
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Late-onset bacterial or fungal sepsis (LOS)
Time frame: Extracted from medical records 1-2 weeks after discharge from the NICU
Experienced with LOS during NICU stay according to Vermont Oxford Network (VON) definition; criteria: yes/no.
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NICU Visitation
Time frame: From NICU admission to discharge or 42 weeks corrected gestational age, whichever comes earlier (maximum of 18 weeks)
Proportion of nursing shifts where mother is present in the NICU.
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Postpartum Bonding
Time frame: Measured in the post-discharge survey within 4-8 week of infant discharge
Score of mother-infant bonding assessed inspired by the Postpartum Bonding Questionnaire, where participants rate their agreement of statements on Likert scales ranging from 0 (always) to 5 (never); scores range from 0 to 50, with higher scores indicating more bonding challenges.
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Provision of breast milk (volume)
Time frame: From NICU admission to discharge or 42 weeks corrected gestational age, whichever comes earlier (maximum of 18 weeks)
Milliliters of nursing shift-total enteral intake that is maternal breast milk fed via gavage tube or bottle.
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Breastfeeding episode
Time frame: From NICU admission to discharge or 42 weeks corrected gestational age, whichever comes earlier (maximum of 18 weeks)
Occurrence of direct breastfeeding episode during each nursing shift.
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Maternal physical health
Time frame: Measured biweekly from NICU admission to discharge or 42 weeks corrected gestational age, whichever comes earlier (maximum of 18 weeks); post-discharge (4-8 weeks); 6 months postpartum; 12 months postpartum
Score of self-reported Short Form Health Survey -1 Physical Health Item; assesses participants' perception of their current physical health. Lower score indicates worse perceived physical health.
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Maternal mental health (anxiety)
Time frame: Measured biweekly from NICU admission to discharge or 42 weeks corrected gestational age, whichever comes earlier (maximum of 18 weeks); post-discharge (4-8 weeks); 6 months postpartum; 12 months postpartum
Score of self-reported 10-item Perceived Stress Scale (PSS-10); assesses the perceived stress levels experienced in terms of overstrain, unmanageability, and unpredictability in the past month. Higher score indicates worse outcome.
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Maternal mental health (depression)
Time frame: Measured biweekly from NICU admission to discharge or 42 weeks corrected gestational age, whichever comes earlier (maximum of 18 weeks); post-discharge (4-8 weeks); 6 months postpartum; 12 months postpartum
Score of the Edinburgh Postnatal Depression Scale (EPDS), a 10-item self-report measure of postpartum depression (ranges from 0-30) with a higher score indicating worse depressive symptoms. The EPDS was developed to assist health professionals in detecting mothers suffering from postpartum depression (PPD).
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Reaction Time Attention Network Test-Revised (ANT-R).
Time frame: Measured biweekly from NICU admission to discharge or 42 weeks corrected gestational age, whichever comes earlier (maximum of 18 weeks)
Average response time across all trials to assess overall speed of responses. Lower scores indicate faster reaction times and better attentional performance.
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Accuracy Performance Attention Network Test-Revised (ANT-R).
Time frame: Measured biweekly from NICU admission to discharge or 42 weeks corrected gestational age, whichever comes earlier (maximum of 18 weeks)
Proportion of accurate responses on the ANT-R. Higher scores indicate higher accurate responses.
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Reaction Time Psychomotor Vigilance Task
Time frame: Measured biweekly from NICU admission to discharge or 42 weeks corrected gestational age, whichever comes earlier (maximum of 18 weeks)
Average reaction time across trials, assessing overall speed and vigilance. Lower scores indicate quicker reaction times and heightened vigilance.
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Accuracy Psychomotor Vigilance Task
Time frame: Measured biweekly from NICU admission to discharge or 42 weeks corrected gestational age, whichever comes earlier (maximum of 18 weeks)
Percentage of correct responses out of the total number of trials on the Psychomotor Vigilance Task (PVT). Higher scores indicate higher accurate responses.
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Happiness
Time frame: Measured biweekly from NICU admission to discharge or 42 weeks corrected gestational age, whichever comes earlier (maximum of 18 weeks); post-discharge (4-8 weeks); 6 months postpartum; 12 months postpartum
Score on Happiness Indicator from Integrated Values Surveys; assesses the overall and current perceived level of happiness experienced; with a 4-point scale from 0 (Not at all happy) to 3 (Very Happy). Higher score indicates better perceived level of happiness.
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Life satisfaction
Time frame: Measured biweekly from NICU admission to discharge or 42 weeks corrected gestational age, whichever comes earlier (maximum of 18 weeks); post-discharge (4-8 weeks); 6 months postpartum; 12 months postpartum
Score of the Life Satisfaction Scale Item; assesses participants' perception of their current overall life satisfaction; with a 4-point scale from 0 (Very Satisfied) to 3 (Not At All Satisfied), and was reverse-coded such that higher scores indicate better perceived life satisfaction.
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Sleep
Time frame: Measured biweekly from NICU admission to discharge or 42 weeks corrected gestational age, whichever comes earlier (maximum of 18 weeks); post-discharge (4-8 weeks); 6 months postpartum; 12 months postpartum
Score of Sleep Quality Score (SQS) with 7-Day Recall; evaluates the overall quality of sleep. Core components include sleep duration, ease of falling asleep, frequency of waking during the night (excluding bathroom visits), early waking, and sleep refreshment. The respondent marks an integer score from 0 to 10, according to the following five categories: 0 = terrible, 1-3 = poor, 4-6 = fair, 7-9 = good, and 10 = excellent. Higher score indicates better perceived sleep quality.
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Routine postpartum care
Time frame: Measured at post-discharge (4-8 weeks after infant discharge from NICU); 6 months postpartum; 12 months postpartum
Number of routine postpartum follow-up visits attended by mom.
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Financial distress
Time frame: Measured biweekly from NICU admission to discharge or 42 weeks corrected gestational age, whichever comes earlier (maximum of 18 weeks); post-discharge (4-8 weeks); 6 months postpartum; 12 months postpartum
Score of financial stress during the NICU stay based on two metrics: difficulty in paying bills and remaining money at the end of the week. Scoring for each question is summed to create an overall financial distress score, ranging from 0 to 8. Higher score indicates higher financial distress.
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Financial hardship
Time frame: Measured within one week of discharge form the NICU; post-discharge (4-8 weeks); 6 months postpartum; 12 months postpartum
Score of financial hardships experienced during the NICU stay, including using up all savings, taking out loans, borrowing from friends, incurring debt, being threatened by eviction, or having a shut-off of an energy utility. Scoring for each question is yes/no and is summed to create an overall score that ranges between 0 and 6.
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Food insecurity
Time frame: Measured biweekly from NICU admission to discharge or 42 weeks corrected gestational age, whichever comes earlier (maximum of 18 weeks); post-discharge (4-8 weeks); 6 months postpartum; 12 months postpartum
Score of Food Insecurity Screening Tool; assesses the risk of food insecurity (availability and affordability) in households based on questions derived from the U.S. Household Food Security Survey Module. Response options include: "Often True," "Sometimes True," "Never True". An affirmative response on either item will be considered to be positive for food insecurity.
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Housing instability
Time frame: Measured within one week of discharge form the NICU; post-discharge (4-8 weeks); 6 months postpartum; 12 months postpartum
Number of moves family has made since their child's birth.
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Housing insecurity
Time frame: Measured within one week of discharge form the NICU; post-discharge (4-8 weeks); 6 months postpartum; 12 months postpartum
Score on housing insecurity scale; assesses participants' worry that they may not have stable housing in the next 2 months. Likert scales ranging from 0 (not at all worried) to 3 (very worried). Higher scores indicate greater levels of housing insecurity.
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Transportation insecurity
Time frame: Measured biweekly from NICU admission to discharge or 42 weeks corrected gestational age, whichever comes earlier (maximum of 18 weeks); post-discharge (4-8 weeks); 6 months postpartum; 12 months postpartum
Score on transportation insecurity item; assesses participants' experience of transportation-related issues affecting their ability to visit the NICU. Likert scales ranging from 0 (never) to 3 (always). Higher scores indicate greater levels of transportation insecurity.
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Length of stay
Time frame: Measured within one week of discharge form the NICU
The total number of days from infant admission to discharge from the hospital.
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Mother readmission between 4-8 weeks post-discharge
Time frame: Measured between 4-8 weeks after discharge of infant from NICU
Any mother readmission to the hospital after her initial discharge.
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Baby readmission between 4-8 weeks post-discharge
Time frame: Measured between 4-8 weeks after discharge of infant from NICU
Any infant readmission to the hospital after initial discharge.
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Mother emergency department visit post-discharge
Time frame: Measured at post-discharge survey (4-8 weeks after infant discharge from NICU); 6 months postpartum; 12 months postpartum
The number of emergency department visits by the mother in the postpartum period.
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Baby emergency department visit weeks post-discharge
Time frame: Measured at post-discharge survey (4-8 weeks after infant discharge from NICU); 6 months postpartum; 12 months postpartum
The number of emergency department visits by the infant after discharge.
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Sleep position
Time frame: Measured between 4-8 weeks after discharge of infant from NICU
Mothers report of exclusive infant supine position to sleep in the last two weeks.
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Sleep location
Time frame: Measured between 4-8 weeks after discharge of infant from NICU
Mothers report exclusively using the room-sharing sleep method, where the infant sleeps in the same room as an adult but on a separate crib or sleep surface, without bed-sharing, in the last two weeks.
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Breastfeeding expression continuation
Time frame: Measured between 4-8 weeks after discharge of infant from NICU
Mothers report of breastfeeding continuation.
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Skin-to-skin care knowledge
Time frame: Measured within one week of discharge form the NICU
Mothers report of knowledge about Skin-to-skin (STS) care based on 4 questions. Scored as a count variable that ranges between 0 and 4.
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Breastfeeding knowledge
Time frame: Measured within one week of discharge form the NICU
Mothers report of knowledge about breastfeeding based on 7 questions. Scored as a count variable that ranges between 0 and 7.
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Perception of hospital experience
Time frame: Measured between 4-8 weeks after discharge of infant from NICU
Assesses mothers' overall perception of hospital experience and hospital services during their stay, using a scale from 0 (worst hospital possible) to 10 (best hospital possible).
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Life's Essential 8 (LE8) behavioral cardiovascular health score
Time frame: Measured at pre-discharge; post-discharge (4-8 weeks, where all components are available); 6 months postpartum; 12 months postpartum
Composite score (0-100) based on four behavioral components: diet quality, physical activity, sleep health, and nicotine exposure, scored according to American Heart Association Life's Essential 8 criteria.
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Primary care utilization in the postpartum period
Time frame: Measured at post-discharge (4-8 weeks); 6 months postpartum; 12 months postpartum
Number of visits with a primary care provider for routine or sick care.
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Adherence to recommended care for chronic conditions
Time frame: Measured at post-discharge (4-8 weeks); 6 months postpartum; 12 months postpartum
Self-reported adherence to recommended postpartum care for chronic conditions (hypertension, diabetes, and mental health), including medication adherence and engagement with healthcare providers for condition management.