Summary characteristics of included documents
| Study | Study design | Country | Population | Pregnancy type | Race or ethnicity included | Ascertainment racial discrimination | Outcome | Ascertainment outcome |
| Barber and Robinson68 | Cross-sectional study | USA | No of participants: 2634 Age range: 15–44 Women part of the Virginia Pregnancy Risk Assessment Monitoring System (PRAMS) recruited from 47 states, New York City, Puerto Rico and the District of Columbia | NR | Non-Hispanic black, non-Hispanic white, Hispanic, non-Hispanic other | Answer to a self-reported question on the PRAMS questionnaire | PTB (<37 weeks’ gestation) LBW (<2500 g) SGA (based on 10th percentile) | Birth certificate data |
| Brown et al 201959 | Cohort study | Australia | No of participants: 344 (165 reporting discrimination or unfair treatment) Mean age: 25 (range 15–43) Women were recruited in urban, regional and remote areas of South Australia over 2 years. Twelve Aboriginal research interviewers recruited women via public hospitals, community-based agencies, community events and their own community networks. To be eligible to take part, women needed to have given birth to an Aboriginal infant in South Australia between June 2011 and July 2013, and to be aged ≥14 years at the time of the birth | NR | Aboriginal | Adapted questions of Indigenous Racism Experience questionnaire (adapted from Paradies et al)103 | LBW (<2500 g), PTB (birth <37 weeks gestation), SGA | Did not report; Australian birth weight standards |
| Dixon et al 201255 | Cohort study | USA | No of participants: 539 mother–infant pairs (176 reporting 1–2 domains of racism, 187 ≥3) Mean age: 30 (5.8) Subjects were participants in Project Viva, a prospective cohort study of gestational factors, pregnancy outcomes and offspring health. Between 1999 and 2002 women who attended their initial prenatal visit at eight obstetric offices of a multi-specialty group practice in eastern Massachusetts were recruited | Singleton | Black, Hispanic, Asian, other | Adapted or expanded Experiences of Discrimination scale measuring lifetime racial discrimination (from Krieger et al, 1990,104 2005)105 | Birth weight for gestational age | US national reference data; length and height measurements performed by research assistants following standardised techniques |
| Dominguez et al 201067 | Cross-sectional study | USA | No of participants: 124 Mean age: 28.65 (5.14) African American, 31.43 (4.07) non-Hispanic white Approached by a research nurse in the prenatal clinic of a large urban medical centre in Los Angeles County or referred by private practitioners with admitting privileges to this medical centre. To be eligible, potential participants had to be ≥18 years, fluent in English, and at no more than 18 weeks gestation with a singleton pregnancy | Singleton | African-American, non-Hispanic white | Answer to a self-reported question on perceived racism (loosely based on items from Krieger et al)104 | Birth weight (g), gestational age at delivery, LBW, preterm delivery | Medical records |
| Janevic et al 201764 | Cross-sectional study | Serbia, Macedonia | No of participants: 410 women (top 25% on EDS were experiencing discrimination) Age: <20: 73; 20–24: 168; 25–29: 106; ≥30: 63 Romani women in Belgrade, Serbia and Skopje, North Macedonia in 2012–2013 who had given birth in the previous 2 years | NR | Romani | Everyday Discrimination Scale (developed by Williams et al)106 | LBW (<2500 g) | Self-report |
| Mustillo et al 200449 | Cohort study | USA | No of participants: 352 (171 experiencing racism) Mean age: 33.1 (3.3) black women, 34.8 (3.2) white women From original 1985 prospective cohort study CARDIA, recruited from four geographically diverse metropolitan areas. Participants who gave birth between 1992 and 1995 were eligible | Singleton | Black, white | Self-reported experiences of racial discrimination based on Krieger’s Experiences of Discrimination scale (from Krieger et al)104 | LBW (<2500 g), preterm deliveries (<37 weeks gestation) | Self-report (at year 10) |
| Thayer et al 201953 | Cohort study | New Zealand | No of participants: 1653 (ever verbal attack 427, ever physical attack 59, unfair treatment 498) Mean age: 29.5 (5.6) Sample from Growing Up in New Zealand (GUINZ) study recruiting pregnant women who had an estimated birth date between 25 April 2009 and 25 March 2010 and living within geographic area defined by Auckland, Counties-Manukau or Waikato District Health Board regions in the North Island of Aotearoea, New Zealand. | Singleton | Māori, Pacific and Asian | Questionnaire asking about lifetime and past experience of unfair treatment (Growing Up in New Zealand questionnaire)107 | LBW (<2500 g), short gestation length (37 weeks gestation) | Medical records |
| Collins et al 200062 | Case–control study | USA | No of participants: 85 (25 cases, 60 controls) Age: no overall statistic clearly reported Subjects were recruited from Children’s Memorial Hospital (neonatal intensive care unit) and Cook County Hospital (neonatal intensive unit, normal newborn nursery) in Chicago | Singleton | African-American | Questionnaire on perception and exposure to racial discrimination during pregnancy (from Krieger et al)104 | VLBW (<1500 g) | Medical records |
| Collins et al 200463 | Case–control study | USA | No of participants: 312 (104 cases, 208 controls) Age: no overall statistic clearly reported Mothers delivering at Cook County Hospital and University of Chicago Hospital in Chicago between 1 November 1997 and 31 October 2000. Cases: mothers of singleton births with VLBW infants and preterm. Controls: mothers of critically ill, singleton non-LBW term infants admitted to neonatal ICU or healthy singleton non-LBW infants admitted to newborn nursery | Singleton | African-American | Questionnaire on perception and exposure to racial discrimination during pregnancy (adapted from Krieger et al 104 and McNeilly et al)108 | VLBW (<1500 g), PTB (<37 weeks gestation) | Medical records |
| Lespinasse et al 200460 | Case–control study | USA | No of participants: 312 women (141 reporting racial discrimination) Age: <19: 82; 19–29: 156; ≥30: 64 Cases were 104 mothers of VLBW infants recruited from the admission logbooks of the NICUs of Cook County Hospital and the University of Chicago Hospital. Controls were 104 mothers of NBW; healthy infants (‘healthy controls’); and 104 mothers of NBW, sick infants who required assisted ventilation or other major life support (‘sick controls’). Healthy controls were recruited from the labour and delivery logbooks and were chosen if admitted near the same date as the cases; sick controls were identified from NICU logbook | Singleton | African-American | Questionnaire that included questions on racism | VLBW (<1500 g) | Medical records |
| Braveman et al 201736 | Cross-sectional study | USA | No of participants: 10 323 women (812 black women (36.9%) reporting chronic worry from discrimination, 446 white women (5.5%)) Age: >15 California Maternal and Infant Health Assessment (MIHA) Cross-sectional California statewide representative surveys of 2201 black and 8122 white, non-Latino, US-born postpartum women with singleton live births during 2011–2014. The MIHA sample is drawn randomly from statewide birth certificate data each year | Singleton | Black, white non-Latino | Questionnaire asking about chronic worry for race-based unfair treatment | PTB (17–36 weeks of gestation) | Birth certificate information and National Centre for Health Statistics criteria; obstetric estimate or LMP for GA |
| Daniels et al 202065 | Cross-sectional study | USA | No of participants: 173 Age range: 30–50 US-born, post-partum women from African-AmericanWomen’s Heart & Health Study (AAWHHS), which includes detailed health information on a community sample of 208 African-American women aged 30–50 residing in the San Francisco Bay Area | NR | African-American | Adapted Everyday Discrimination Scale, adapted a scale (adopted from Krieger et al)105 | Preterm labour (<37 weeks gestation) | Self-report |
| Dole et al 200356 | Cohort study | USA | No of participants: 1962 (574 reporting some or higher discrimination) Age range: 16–19: 274; 20–29: 1036; ≥30: 652 The Pregnancy, Infection, and Nutrition Study, a prospective cohort study of risk factors for PTB, recruited women from two prenatal clinics in central North Carolina who were between 24 and 29 weeks’ gestation, beginning in August 1995 | Singleton | African-American | Psychological self-reported questionnaire (adapted from Krieger,104 Krieger and Sidney)109 | PTB (<37 weeks gestation) | Medical records |
| Dole et al 200457 | Cohort study | USA | No of participants: 1898 (364 black women reporting discrimination, 271 white women) Age range: 16–19: 261; 20–29: 1002; ≥30: 635 The Pregnancy, Infection, and Nutrition (PIN) Study was conducted in central North Carolina at two prenatal care sites (>16 years of age, between 24 and 29 weeks gestation. Self-reported white or African American). | Singleton | African-American, white | Adapted Experience of Discrimination Scale (Krieger) (adapted from Krieger104 Krieger and Sidney)109 | PTB (<37 weeks gestation) | Medical records; algorithm using LMP or earliest US before 20 weeks |
| Fryer et al 202039 | Cohort study | USA | No of participants: 1732 (736 reporting medium or high discrimination) Mean age: 24.2 (5.0) non-Hispanic African American, 25.7 (5.2) Latina Community Child Health Research Network Study, a 5-year, multisite, prospective cohort study. Women were recruited from Baltimore, Chicago, North Carolina, Los Angeles and Washington DC from 2008 to 2012 and followed up over a 2-year period. 18–40 years of age | Singleton | African-American, Latina | Everyday Discrimination Scale (developed by Williams et al)106 | Spontaneous preterm delivery (<37 weeks) | Medical records |
| Giurgescu et al 201266 | Cross-sectional study | USA | No of participants: 72 (no reporting discrimination not reported) Mean age: 23.38 (5.44) full term, 23.27 (5.24) preterm African-American women ≥18 years old, at least 24 weeks gestation at birth, at least 24 hours after birth and medically stable in Chicago hospital. Excluded if had medical comorbidity, unstable or had medically indicated birth | Singleton | African-American | Adapted Experiences of Discrimination scale (adapted from Krieger et al, 1990,104 2010110 | PTB (<37 weeks gestation) | Medical records based on LMP and confirmed by US |
| Misra et al 201038 | Cohort study | USA | No of participants: 832 (425 experiencing racism) Mean age: 23.1 (5.6) African-American women residing in Baltimore, Maryland, enrolled prenatally if they received care at one of three Johns Hopkins Medical Institution (JHMI) prenatal clinics or enrolled post-partum if they delivered at JHMI with late, none or intermittent prenatal care | Singleton | Black or African-American, Hispanic | Racism and Lifetime Experiences Scale (RaLES), RaLES Daily Life Experiences Scale (DLE), Racism‐Related Experiences Scale (RRE) (from Harrell et al)111 | PTB (<37 weeks gestation), gestational age | Medical records |
| Rankin et al 201161 | Case–control study | USA | No of participants: 277 (160 cases, 117 controls) Age: <20: 60; 20–34: 186; ≥35: 31 African-American mothers delivering at Stroger Hospital of Cook County and Unversity of Chicago Hospital in Chicago, IL between July 2001 and June 2005 | Singleton | African-American | Adapted Perceived Racism Scale (adapted from McNeilly et al)108 | PTB (<37 weeks gestation) LBW (<2500 g) | Medical records |
| Rosenberg et al 200250 | Cohort study | USA | No of participants: 4966 Age range: 21–69 Follow-up study from Black Women’s Health Study (1995) recruiting US African-American women. Those completing 1997–1999 questionnaires and reported singleton birth were eligible | Singleton | African-American | Nine questions regarding their experience of racial discrimination | PTB (<37 weeks gestation) | Self-report |
| Scholaske et al 201951 | Cohort study | Germany | No of participants: 2515 (46 experiencing racism) Mean age: 31.43 (5.44) German autochthonous, 30.71 (5.68) Turkish immigrant women Sample from German Socio-Economic Panel (SOEP) study of German autochthonous and Turkish immigrant women who recently gave birth, within first year after delivery | Singleton | German autochthonous Turkish | Self-report: single item asking frequency of perceived discrimination | PTB (<37 weeks gestation) | Self-report (from newborn questionnaire) |
| Slaughter-Acey et al 201637 | Cohort study | USA | No of participants: 1232 women (DLE-B score second quartile 305, third 307, fourth 315) Age range: 21–69 Sample from the Life-course Influences of Fetal Environments (LIFE) study which recruited black or African-American women aged 18–45 years who gave birth to a singleton at a surburban hospital in metropolitan Detroit | Singleton | Black or African-American | RaLES Daily Life Experiences Scale (DLE) scale of Racism and Bother (from Harrell et al)111 | PTB (<37 weeks gestation) | Medical records; algorithm to estimate GA (based on early US, LMP, later US or clinician’s estimate) |
| Wheeler et al 201854 | Cohort study | USA | No of participants: 1606 women (1256 black, 350 white) Mean age: primiparous: 23.5 (5.8); multiparous term birth: 26.7 (6.2); multiparous PTB: 27.7 (5.6) English-speaking pregnant women enrolled in Healthy Pregnancy, Healthy Baby Study in Durham, North Carolina, USA. Participants received their care at the Duke Obstetrics Clinic of the Durham County Health Department Prenatal Care | Singleton | Non-Hispanic black, non-Hispanic white | Perceived Racism Scale (from Dole et al,57 adopted Krieger et al 104 and Krieger and Sidney)109 | PTB (spontaneous) | Medical records; enrolment interview |
| Slaughter-Acey et al 201952 | Cohort study | USA | No of participants: 778 (730 acknowledged at least one item of racism, 48 did not acknowledge any item) Mean age: 23.3 (5.7) Black or African-American women living in Baltimore City, Maryland who attended JHMI satellite prenatal clinic or delivered a live infant at JHMI | NR | Black or African-American | Adapted Racism and lifetime Experience Scale (RaLES) (from Harrell et al)111 | SGA | SGA determined using cut-off point for birth weight ratio continuous measure (observed birth weight divided by expected birth weight for infant’s GA) |
| Grobman et al 201858 | Cohort study | USA | No of participants: 9470 women (N reporting racial discrimination not reported) Age: no overall statistic clearly reported The Nulliparous Pregnancy Outcomes Study: Monitoring Mothers-To-Be is a prospective cohort study in which 10 038 nulliparous women (>13 years of age) with singleton pregnancies were enrolled from geographically diverse hospitals affiliated with eight clinical centres | Singleton | Non-Hispanic white, non-Hispanic black, Hispanic, Asian, other | Krieger Racism Scale (developed by Krieger et al)105 | Hypertensive disorder of pregnancy, SGA, PTB (<37 weeks gestation) | Medical records |
GA, gestational age; LBW, low birth weight; LMP, last menstrual period; NICU, newborn intensive care unit; NR, not reported; PTB, preterm birth; SGA, small for gestational age; US, ultrasound; VLBW, very low birth weight.