Table 1 Characteristics of posttraumatic stress (PTS) included studies

Anchan 2021, [22] USA

Prospective cohort,1 centre, June 2018-October 2019, NICU level 3, length of stay > 7 days

To determine the incidence of mental health symptoms in military families after NICU admission

Mothers and self-identified partners, > 18 yrs, English-speaking Department of Defense (DoD) Beneficiaries, infant remained admitted to NICU ≥ 7 days

Parents who were unable to maintain follow-up within military healthcare system beyond 7 days

N = 106 parents ( 66 mothers + 40 fathers) at 2 wks post birth (T1), N = 77 parents ( 53 mothers + 24 fathers) at 4–6 wks post NICU discharge (T2) Age – parents ≥ 35 yrs = 80 (75%) < 35 yrs = 26 (25%) SES—house income > $50.000 = 88 (83%) Ethnicity could select ≥ 1 White = 73 (69%), Other = 46 (31%) Education—college/trade school and higher = 74 (70%) LWP & parity = NR

N & BW = NR, GA = 35–38 and > 38 wks

Brunson 2021, [23] France

Prospective cohort, 3 centres, January 2008 and January 2011, NICU, length of stay = NR

To estimate the prevalence and predictive factors of mothers affected by posttraumatic symptoms after preterm birth

Mothers who delivered prematurely < 32 wks

Mothers with acute or chronic psychological illness, drug or alcohol abuse, underage, not speaking French For newborns life-threatening conditions, malformation and/or genetic abnormalities, and/or vulnerability of the baby evaluated by Perinatal Risk Inventory ≥ 10

N = 50 mothers

Age = mean 30.9 ± SD 5.4 yrs

Parity—nullips = 21 (42%)

Education = graduated from high school = 40 (80%)

SES, LWP & ethnicity = NR

N = 50, GA = mean 209.8 ± SD 10.9 days, BW = mean 1331 ± SD 350 g

Chang 2016, [24] Taiwan

Cross-sectional, 1 centre, January 2010-June 2011, length of stay < 60.00 ± 53.78 days, NICU level = NR

To estimate the prevalence of symptoms of distress in mothers of preterm NICU infants and factors complications of delivery for these symptoms

Mothers to babies < 37 wks gestation, admission to the NICU, and infant survival at the time of the interview

Mothers who did not understanding Chinese, refused to consent, babies with congenital chromosomal abnormalities/congenital defects, significant heart disease after birth, or died during the hospital stay or after leaving the NICU Mothers with major illnesses, cancer, or psychiatric disorders

N = 102 mothers

Age = mean 34.28 ± SD, 4.45

Parity—nullips = 37 (36.27%)

Education > 12 yrs = 95 (94.14%)

SES—household income ≤ 600,000 NTD (about 19,679 USD) = 52 (50.98%)

LWP & ethnicity = NR

N = 102, GA = 31.53 SD ± 2.97 wks, BW = 1661.86 ± SD 563.82 g

Clark 2021, [25] USA

Cross-sectional, 1 centre, July 2009-July 2014, NICU level IV, length of stay = NR

To study the associations between parents perceptions of infant symptoms and suffering and parent adjustment following the baby death

Parents of infants who died within the previous five yrs in level IV NICU

Age < 18 yrs, infants died within the past 3 months, not speaking English

N = 40 mothers,

N = 27 fathers (27 mother-father dyads, 13 only mothers)

Age – mothers = mean 33.33 ± 6 yrs

Age – fathers = mean 36.74 ± 9.49 yrs

LWP – mothers = 32 (80%)

LWP – fathers = 24 (60%)

Ethnicity – mothers = white 35 (88%)

Ethnicity – fathers = white 16 (58%)

Education – secondary—mothers = 34 (85%)

Education—secondary – fathers = 18 (67%)

SES—family income = range $50–75,000 for all Parity = NR

N = 40, BW & GA = NR

Eutrope 2014, [26] France

Prospective cohort, 3 centres, January 2008-January 2010, NICU, length of stay = NR

To clarify the relationship between the mother’s post-traumatic reaction and premature birth and the mother-infant interactions

Mothers to infants < 32 wks

For mothers: Psychiatric illness, drug or alcohol abuse, aged < 18 yrs, language barriers; For newborns: Unfavourable vital prognosis evaluated Perinatal Risk Inventory score ≥ 10 infants risk of significant developmental disabilities and malformation and/or genetic anomaly diagnosed

N = 100 mothers during 15 days after birth, N = 93 before NICU discharge

Age = mean 329.8 ± 6 yrs Parity—nullips = 48 (48%) LWP = 92 (92%) Education – higher = 79 (79.29%) SES – employed = 69 (69%) Ethnicity = NR

N = 100, BW = mean 1320g, GA < 32 wks

Garfield 2015 ^a [27], USA

Cross-sectional, 2 centres, length of stays = 31—211 days, mean = 93.1 ± SD 48.49 days, NICU level & period = NR

To identify risk factors among urban, low-income mothers, to enable NICU healthcare providers more effectively screening and referral

Mothers of VLBW < 1500 g and preterm < 37 wks, English peaking, no current mental health diagnosis, infants clinically stable and did not have a congenital neurological problems or symptoms of substance abuse

Mothers’ age < 18 yrs old, ongoing critical illness (HIV, seizure), major depression, psychosis, bipolar disease; mothers to infants receiving mechanical ventilation

N = 113 mothers

Age = mean 24.7 ± SD 5.17 yrs

LWP = 59 (52.3%)

SES—received public aid = 44 (39%)

SES – uninsured = 45 (40%)

Ethnicity—African American = 92 (81%)

Education—high school graduates = 49 (43%)

Parity = NR

N = NR, GA < 37 wks, BW = mean 1,073 ± SD 342 g

Greene 2015 & 2019 ^a [28], USA

Prospective cohort, 1 urban centre, 2011–2012, NICU level IV, length of stay = mean 91 ± SD 37 days

To analyse change of depression, anxiety and perinatal-specific PTS across VLBW infants’ first year of life and to identify predictors of these changes over time

English-speaking mothers, > 18 yrs, babies likely to survive and VLBW < 1500 g

NR

N = 69 at birth, N = 64 before NICU discharge

Age = mean 27 ± SD 6 yrs Parity—nullips = 23 (34%)

LWP = 32 (51%)

Ethnicity—Black = 38 (54%), Non-Hispanic white = 18 (26%), Hispanic = 12 (17%), Asian = 1 (1%)

Education – yrs of higher grade = 13.4 ± SD, 2.4

SES = NR

N = 69, GA = mean 27.5 ± SD 2 wks, range 23.2 to 32.3 wks, BW = mean 957 ± SD, 243 g

Hawthorne 2016, [30] USA

Prospective cohort, 8 centres, period = NR, 4 NICU level III, 4 PICU, length of stay = NR

To test the relationships between spiritual/religious coping strategies and grief, mental health and personal growth for parents to babies died in intensive care unit

Parents were eligible for the study if their deceased newborn was from a singleton pregnancy and lived for more than 2 h in the NICU or their deceased infant/child was 18 yrs or younger and a patient in the PICU for at least 2 h

Parents who did not speak English or Spanish, multiple gestation pregnancy if the deceased was a newborn, being in a foster home before hospitalization, injuries suspected to be due to child abuse, death of a parent due to illness/injury event

N = 165 both parents (114 mothers + 51 fathers)

Age = mean mothers 31.1 ± SD 7.73 yrs, fathers = 36.8 ± SD 9.32 yrs

LWP = mothers 84 (74%) LWP = fathers 43 (84%)

SES – mothers employed = 63 (55%)

SES- fathers employed = 32 (78%)

Ethnicity – mothers white non -Hispanic = 22 (19%), black non-Hispanic = 50 (44%), Hispanic = 42 (37%)

Ethnicity – fathers white non – Hispanic = 14 (28%)

 = black non-Hispanic = 16 (31%), Hispanic = 21 (41%),

Education – mothers college degree = 35 (30%)

Education – fathers college degree = 19 (37%)

Parity = NR

N = 124

(69 NICU and 55 PICU), GA & BW = NR

Holditch-Davis 2009 ^a [31], USA

Prospective cohort, 2 centres, NICU level & study period = NR

To examine inter-relationships among stress due to infant appearance and behaviour in the NICU exhibited by African American mothers of preterm infants

African American biological mothers of preterm infants < 1500 gm at birth or requiring mechanical ventilation. Mothers were recruited when their infants were no longer critically ill

Infants with congenital, symptomatic from substance exposure, hospitalized > 2 months post-term, or triplets or part of a higher order multiples set; mothers with no custody, follow-up for 2 yrs unlikely, HIV + , < 15 yrs, critically ill, not speak English, mental health problems

N = 177 mothers

Age = mean 25.9 ± SD 6.5 yrs

LWP = 46 (26.1%)

SES—Public assistance = 92 (52.8%)

Education = mean 12.6 ± SD 1.8 yrs

Ethnicity = all African American

Parity = NR

N = 190, mean GA = 28.3 SD ± 2.9 wks, mean BW = 1107 ± SD,394 g

Jubinville 2012, [32] Canada

Prospective cohort, 1 centre, February-May, 2008, NICU, level III, Length of stay = NR

To determine whether significant symptoms of (ASD) are present in mothers of premature NICU infants

Mothers of infants’ < 33 wks GA admitted to NICU

Infant with foetal anomaly, severe illness requires compassionate care and/ maternal illness precluded NICU visit and assessing women at 7–10 days after birth

N = 40 mothers

Age = mean 29.2 ± SD 5.8 yrs

LWP = 37 (93%)

SES—income $60, 000 per year = 23 (58%)

Ethnicity = majority white

Education—above high school = 24 (60%)

Parity = NR

N = 52, 10 twins, & one triplets, BW = mean 1374.5 ± SD 466.1 g range = 640–2220 g, GA = mean 29.0 ± SD 2.6 wks, range = 24.0–32.0 wks

Kim 2015, [33] South Korea

Prospective cohort, 1 centre, April to October 2009, NICU, level & length of stay = NR

To understand the progress and predictor factors of PTSD in mothers of high-risk infants

Mothers age of 18 to 45 yrs and who did not have a significant medical/surgical history that affected their performance on the self-report questionnaires

Mothers who did not speak Korean or problem executing the self-report questionnaires

N = 120 mothers (90 without PTSD + 30 0 with PTSD)

Age—no PTSD = mean 31.87 ± SD 3.50 yrs,

Age – PTSD = mean 31.83 ± 3.23 yrs

LWP – no PTSD = 89 (98.9%)

LWP – PTSD = 30 (100%)

SES—employed—no PTSD = 34 (39.5%)

SES – employed—PTSD = 14 (50.0%)

Education—level ≤ 14 yrs no PTSD = 32 (36.0%)

Education—level ≤ 14 yrs PTSD = 10 (33.3%)

Ethnicity & parity = NR

N = NR, GA—no PTSD = mean 33.89 ± 3.76 wks

GA – PTSD = mean 33.27 ± SD 3.91) wks, BW—no PTSD = mean 2.03 ± SD 0.78, BW—PTSD = mean 2.01 ± SD 0.72 kg

Lefkowitz 2010, [34] USA

Prospective cohort, 1 centre over a 9 months period, length of stay = median 14 days, NICU level = NR

To assess the prevalence and correlates of ASD and PTSD in mothers and fathers

Mothers and fathers of infants on NICU who were anticipated to stay on NICU > 5 days

Inability to read English, parent age < 18 yrs, or if the child’s death appeared imminent

N = 130 parents ( 89 mothers + 41 fathers)

Age—mothers = mean 29 yrs

Age—fathers = mean 33 yrs

Ethnicity—mothers Caucasian = 61 (71%), Ethnicity—fathers Caucasian = 33 (81%)

Education—mothers college degree = 21 (24.4%)

Education—fathers college degree = 9 (21.4%)

Parity, LWP & SES = NR

GA < 30 wks N & BW = NR

Lotterman 2018 ^a [45], USA

Prospective cohort, 1 centre, NICU level III & IV, period & length of stay = NR

To investigate whether rates of psychopathology are elevated in mothers of moderate- to late preterm infants during/following infant hospitalization in the NICU, and associated protective and risk factors

Mothers of moderate- to late preterm infants GA 32 to < 37 wks

Mothers to babies born < 32 wks or later than 36 wks, or if they had been in the NICU for > 6 months

N = 91 mothers at NICU admission, N = 76 at 6 months

Age = mean 32.45 SD ± 6.78 yrs

Ethnicity = Caucasian 37 (40.7%),

African American 15 (17.4%)

Asian 9 (10.5%), American Indian/Alaskan Native 2 (2.3%), 27 (29.1%) other

Education—mean yrs 14.29 ± SD 4.30

Parity, LWP & SES = NR

N = 91, GA = range 32–37 wks, GA = mean 33.53 ± SD, 1.33 wks, BW = NR

Malin’s study, USA

Malin 2020 [46]

Cohort study, 1 centre, NICU – level IV, length of stay ≥ 14 days, period = NR

To determine if PTSD among parents after an NICU discharge can be predicted by objective measures or perceptions of infant illness severity

Parent of infants who were in NICU ≥ 14 days

Parents who did not speak English, infants discharged home with their non-biological parent, infant was previously discharged home or transferred to/from the cardiac ICU for surgery, infants who died in NICU

N = 164 parents

LWP = 154 (94%)

SES—government insurance = 82 (50%)

Parity, ethnicity & education = NR

N = 164, GA = 23–28 wks (n = 36), 29–33 wks (n = 60), 34–36 wks (n = 29), > 37 wks (n = 39), BW < 1000 g (n = 28), BW > 1000 g (n = 136)

Malin 2022 [46]

Cohort study, 1 centre, September 2018-March 2020, NICU level IV, length of stay = mean 68.1 ± 65.6 days

To explore parents’ uncertainty during and after NICU discharge and the relationship between uncertainty and PTS

Parent of infants who were in NICU ≥ 14 days and had not previously been discharged from hospital

Parents not fluent in English, parents of infants whose death appeared imminent or who would be transferred to cardiac ICU before discharge;

parents who would not be caring for infant post-discharge, parents of infants who died after enrolment, only one parent of each infant could participate

N = 319 parents during NICU, N = 245 parents at 3 months

Age = mean 29.9 ± SD 5.59 yrs

SES—unemployed = 52 (21%)

Ethnicity = white 214 (67.3%), Black of African American 76 (24.0%), Asian 8 (2.5%), American Indian or Alaska Native 3 (0.1%), Other 17 (5.3%)

Education—graduate 39 (12.2%)

Parity & LWP = NR

N = 243, GA = 22–25 wks = 34 (10.7%), 26–28 wks = 37(11.6%), 29-31wks = 60 (18.8%), 32–36 wks = 119 (37.3%), ≥ 37wks = 69 (21.6%) range 22- ≥ 37 wks, BW = NR

Misund 2013 & 2014 ^a Norway [36, 37],

Cohort study, 1 centre June 2005-July 2008, NICU level & length of stay = NR

To explore psychological distress, anxiety, and trauma related stress reactions in mothers experienced preterm birth and the predictors of maternal mental health problems

Mothers to preterm babies < 33 wks admitted to NICU

Mothers of severely ill babies that the medical staff estimated to have poor chance of survival, and non-Norwegian speakers

N = 29 mothers at 2 wks post birth, N = 27 at 2 wks after NICU admission, N = 26 at 6 & 18 months post term, Age = mean age 33.7yrs ± SD 4.3 yrs

Parity—nullips = 18 (62.1%)

LWP = all

SES – unemployed = 4 (13.8%)

Education > 12 yrs = 26 (89.7%)

Ethnicity = NR

N = 35, GA = median 29, range 24–32) wks median BW = 1.2 kg (range 0.6–2.0), 40% twins

Moreyra 2021 ^a USA [47],

Cross-sectional, October 2017-July 2019, length of stay at least 14 days, number of centres, period & NICU level = NR

To describe the impact of depression, anxiety, and trauma screening protocol and the referral pf positively screened NICU parents

Parents of NICU babies admitted at least for 2 wks

None excluded

N = 150 parents (120 mothers + 30 fathers)

Age = 31.06 ± 6.26 yrs

Parity—Para = mean 1.95 ± SD 1.2

LWP = 91 (61%)

Ethnicity = white 39 26%, Other = 111 (74%)

Education & SES = NR

N = NR, mean GA = 32.3 ± 4.8 wks, BW = mean 1935.2 ± SD 1052.1 g

Naeem 2019, Iran [38]

Cohort, 2 hospitals, 2016, NICU level & length of stay = NR

To compare the prevalence of PTS and its related risk factors in parents of hospitalized preterm and term neonates

Parents of NICU preterm (GA 24—36 wks) and parents to hospitalized terms (GA > 38 wks), inafnts’ age 2–5 days

History of psychological or psychotic problems with the experience of hospitalization, medication or psychiatric consultation, underlying diseases, and drug abuse

N = 160 parents (80 mothers + 80 fathers)

Age – mothers = mean 33.78 ± SD 1.03 yrs

Age – fathers = mean 37.14 ± SD 1.17 yrs

LWP = all

SES – employed = mothers 12 (15.25%)

SES – employed = fathers 92.4%

Education – mothers > high school = 72.2%,

Education – fathers > high school = 52 (64.6%)

Parity = NR

N = 80, GA = 24–36

wks, BW = NR

Pace 2020, Australia [39]

Prospective cohort, 1 centre, 2011–2013, NICU level & length of stay = NR

To report the proportion of parents of VPT infants with PTS symptoms at different time points

Families with very preterm infants, GA < 30 wks admitted to NICU

Parents who did not speak English, infants with congenital abnormalities, unlikely to survive

N = 105 parents (92 mothers and or 75 fathers)

Age – mothers = mean 33 ± SD 5.3 yrs

Age – fathers = 35 ± SD 6.2 yrs

SES- high risk parents = 45 (43%)

Education—mothers > 12 yrs = 62 (67%)

Education – fathers > 12 yrs = 45 (60%)

Parity, LWP & ethnicity = NR

N = 131, GA < 30 wks, GA = mean 27.8 ± SD 1.5 wks, BW = mean 1,038 ± 261 g

Pisoni 2020 ^a Italy [49],

Prospective cohort, 1 centre, August 2013-April 2014, length of stay = mean 29, range 13–138 days, NICU level = NR

To examine maternal psychological, parental, perinatal infant variables and neurodevelopment

Preterm infants gestational age < 34 wks and their mothers age > 18 yrs old, speaking Italian

Congenital anomalies, infections, no psychiatric illness and/or drug abuse

N = 29 mothers

Age = mean 32.79 ± 6.74 yrs

Parity—nullips = 19 (65.52%)

SES—employed = 25 (86.21%)

Education = mean 14.31 ± 2.78 yrs LWP & ethnicity = NR

N = 29, GA = mean 30.23 ± SD 3.16, range 23–33 wks, BW = mean 528.9 5 ± SD 41.15 g, range 574–2327 g

Rodriguez 2020, Argentina [40]

Cohort, 1 centre, March 2014-November 2016, NICU level & length of stay = NR

To detect PTS frequency and symptoms among mothers of VLBW preterm < 32 wks

Mothers with singleton pregnancies to VLBW < 1,500g preterm babies < 32 wks

Mothers with psychiatric disorders before and/or during gestation, babies with chronic conditions & congenital malformations

N = 146 mothers

Age = range ≤ 21 to ≥ 42 yrs

Parity, LWP, SE, ethnicity & education = NR

N = 146, GA < 32 wks,

BW < 1,500 g

Salomè 2022, Italy [48]

Prospective cohort, 1 centre, September 2018-September 2019, tertiary-level NICU, length of stay = NR

To determine the impact of parental psychological distress and psychophysical wellbeing on developing PTS at 1st yr post NICU discharge and any differences between mothers and fathers

Any couples to infants admitted to NICU during the study duration

NR

N = 40 parents (20 couples, 20 mothers + 20 fathers)

Age – mothers = mean 34 ± SD 6.6 yrs range 27 to 49 yrs

LWP = all

Education—university degree = 5 (25%)

Parity, SES & ethnicity = NR

N = 23, BW = mean 1,375 ± SD 458.57 g, range = 760–2500 g, GA = mean 31 ± SD 2.99 wks range = 25 to 36 wks

Sharp 2021, USA [41]

Cross-sectional – media survey, November 2015-

July 2016, length of stay = 29.57 (26.79) days, number of centres and NICU level = NR

To report on maternal perceived stress to infants’ NICU admission and the relationship between traumatic childbirth and PTSD

Biological mothers ≥ 18 yrs old, USA residents, complete the survey in English, alive infants age 1–4 months

Completing < 75% of the survey, infants age > 1–4 months

N = 77 mothers

Age = mean 39.6 ± 5.8 yrs

Parity—nullips = 32 (41.6%)

SES—unemployed = 26 (47%)

Ethnicity = White 68 (88.3%), Hispanic 7 (9.1%) Education (Bachelor’s degree or above) = 35 (45%)

N = NR, BW < 2,500g = 47 (61.0%)

, GA < 37 wks = 43 (55.8%)

Shaw 2009, USA [42]

Prospective cohort, 1 centre, NICU, length of stay = mean 12 ± 8 days, study period = NR

To describe the early-onset symptoms of ASD in parents and factors related to PTSD, identifying high-risk parents who may benefit from early intervention

English-speaking parents of NICU infants

NR

N = 40 parents (25 mothers + 15 fathers)

Age – mothers = 34.55 ± SD, 4.41 yrs

LWP = all

SES – employed = mothers 18 (72%)

SES – employed = fathers all

Ethnicity – mothers = white 15 (60%)

Ethnicity—fathers = white 12 (92.3%)

Education—university and above = mothers 17 (52%)

Education – university and above = fathers 12 (92%)

Parity = NR

N = NR

GA = 30.89 SD ± 4.11 wks, range = 27 to 41 wk, BW = mean 1,664.39 ± SD, 908.21 g range = 1052 to 4004 g

Vinall 2018, Canada [43]

Cohorts, 1 centre, July 2012 and March 2016, length of stay = mean 57.89 ± SD 35.87 days, NICU level = NR

To examine whether the number of invasive procedures together with mother’s memory for these procedures were associated with PTSS at discharge from the NICU

Mothers of infants < 37 wks GA

Infants were excluded if they had major congenital anomalies, were receiving opioids, or underwent surgery

N = 36 mothers

Age = median 31, IQR 27–36 yrs

Education = median 5 IQR, 4–5 yrs,

Parity, LWP, SES & parity = NR

N = 36, GA median (IQR) 32 (30–34) wks, BW = NR

Williams 2021, USA [44]

Cross sectional, 1 centre, over 6 months, date = NR, level IV NICU, length of stay = 44.82 ± 51.37 days

To evaluate acute stress disorder (ASD) symptoms and their predictors in NICU mothers

English speaking biological mothers

Mothers with infants with brief lengths of stay

N = 119 mothers

SES—Medicaid insurance = 85 (71.8%)

Ethnicity = African American 58 (48.7%), Caucasian 47 (39.5%), Hispanic/Latinos 10 (7.6%), Asians 3 (2.5%)

Education – college degree or higher = 41 (33.6%)

Age, parity & LWP = NR

N = 115, GA = 33.2 ± 4.66 < 28 wks to > 37 wks, BW = 2278.43 ± 1037 g