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Table 2 Characteristics of included studies

From: Nutrient intakes and nutritional biomarkers in pregnant adolescents: a systematic review of studies in developed countries

Study Information Participants Supplements Measurement Quality
Study Country Study design Study groups Number Age Inclusion criteria Exclusion criteria Supplement type and dose Number with available data Estimated compliance: N (%) Data collection method (s) Time period(s) Quality rating
Baker et.al (2009) [23] UK Cross-sectional study NA 500 14–18 Singleton pregnancy, age 14–18, gestational age < =20 weeks Inability to provide informed consent, preeclampsia, clotting disorders, HIV/AIDS, haemoglobinopathies, diabetes, renal disease, hypertension, multiple gestations, history of 3= > previous miscarriages Preconception folic acid 498 34 (6.9) 24 h recall (multiple) Third trimester +
Folic acid in early pregnancy 498 220 (44.2)
Iron in early pregnancy 498 39 (7.8)
Multivitamins in early pregnancy 498 19 (3.8)
Folic acid only in 3rd trimester 290 5 (1.7)
Iron and folic acid in 3rd trimester 290 13 (4.5)
Iron only in 3rd trimester 290 42 (14.5)
Multivitamins in 3rd trimester 290 7 (2.4)
Castillo-Duran et.al (2001) [43] Chile RCT Zinc supplemented 249 16.4 (mean) Beginning prenatal visits before 20 weeks gestation, aged <19 at estimated due date Adolescents whose background included chronic diseases, drug abuse, mental retardation, illiteracy or pregnancy due to incest or rape 20 mg Zinc sulphate daily Intervention group - 249 At least 50 % compliance 24 h recall (multiple) Second and third trimester +
Placebo 258 40 mg iron sulphate All participants - 507  
Chan et.al (2006) [24] USA RCT Control group, 2 intervention groups excluded from review* 23 15–17 Enrolled before 20 weeks gestation Hypertension, diabetes, renal or liver disease, alcohol or tobacco use, using medicines effecting Ca metabolism No additional supplements reported    Food diary (weighing not mentioned) Second and third trimester −/+
Chang et.al (2003) [37] USA Retrospective chart review NA 918 12–17 Self-reported racial group as African-American; singleton pregnancy Birth results not available due to abortion, miscarriage or transfer of care 90 mg carbonyl iron daily plus additional up to 120 mg for those classified as anaemic 918 Not reported Not reported Second and third trimester +
Dawson et.al (2000) [35] USA RCT One-A-Day without Iron 20 16–20 Aged 16–20, less than 16 weeks gestation, no iron supplementation for previous 30 days Hypertension; diabetes; other medical problems; haemoglobin <11 g/dL; haematocrit <30 % Vitamin A 5000 IU, vitamin D 400 IU, vitamin E 10 mg, vitamin C 60 mg, folic acid 0.4 mg, thiamine 1.5 mg, riboflavin 1.7 mg, niacin 20 mg, pyridoxine 2 mg, vitamin B- 6 mg, pantothenic acid 10 mg 20 Not reported Venous blood sample Second and third trimester and delivery −/+
One-A-Day with Iron 20 18 mg Iron, Vitamin A 5000 IU, vitamin D 400 IU, vitamin E 10 mg, vitamin C 60 mg, folic acid 0.4 mg, thiamine 1.5 mg, riboflavin 1.7 mg, niacin 20 mg, pyridoxine 2 mg, vitamin B- 6 mg, pantothenic acid 10 mg 20
Derbyshire (2009) [39] UK Cross-sectional study NA 20 15–19 Attending antenatal classes or community clinics Incomplete diary None reported    Food diary unweighed Third trimester +
Gadowsky et.al (1995) [42] Canada Cross-sectional study NA 58 14–19 Not reported Not reported Folic Acid Mean 479 μg/day 58 82 % Venous blood sample Third trimester +
Elemental Iron Mean 31.5 mg/day
Cyanocobalamin (B12) Mean 2.24 μg/d
Giddens et.al (2000) [27] USA RCT (subset from a larger study) NA 59 13–18 Singleton pregnancies, between 13 and 19 weeks gestation Not reported Reported that any contribution from supplements was not included in analysis    Food diary weighed Mean over pregnancy −/+
Ginde et.al (2010) [32] USA Secondary analysis of cross sectional survey NA 84 13–19 Not reported Not reported Some participants taking vitamin D supplements Not reported Not reported Venous blood sample Mean over pregnancy +
Gutierrez et.al (1999) [28] USA Cross-sectional study NA 46 13–18 Self-identified ethnicity as Mexican American, primigravida, 13–18 years of age History of miscarriage or health problems, involved in competitive athletic performances or heavy exercise, planned to move away during study period None reported    24 h recall (single) Second and third trimester +
Iannotti et.al (2005) [36] USA Cross-sectional study NA 80 13–18 Self-reported racial group as African-American; singleton pregnancy Not reported None reported    10 ml Venous blood sample Second and third trimesters +
Job et.al (1995) [41] Australia Cross-sectional study NA 35 13–19 Not reported Not reported None reported    24 h recall Mean over pregnancy +
Lee et.al (2013) [25] USA Cross-sectional study NA 156 13–18 Age 18 or under, carrying a single fetus, 12–30 weeks gestation at recruitment Not reported Reported that any contribution from supplements was not included in analysis    24 h recall (multiple) <23 weeks gestation, 23–30 weeks gestation and Mean over pregnancy +
McGuire et.al. (2010) [31] USA Cross-sectional study NA 80 Under 18 (mean 16.5) Self-reported ethnic group as African American, singleton pregnancy Not reported Routinely prescribed prenatal supplements containing 400 IU vitamin D   Data not available Venous blood sample Second and third trimester +
Meier et.al (2002) [34] USA RCT Iron supplemented 20 15–18 Not reported Iron deficiency anaemia at recruitment 60 mg elemental iron & 1 mg folic acid 20   Venous blood sample Second and third trimesters +
Placebo 17 1 mg folic acid 17
Mistry et.al (2014) [40] UK Cross-sectional study Appropriate for gestational age babies 107 14–18 Not reported Inability to provide informed consent, pre-eclampsia, clotting disorders, HIV/AIDS, Haemoglobinpathies, diabetes, renal disease, hypertension, multiple pregnancy and previous miscarriage None reported    30 ml venous blood sample Third trimester +
Small for gestational age babies 9
O’Brien et.al (2003) [33] USA Cross-sectional study NA 23 Mean 16.5 First, singleton pregnancies; no medical problems; no medications known to influence calcium metabolism; non-smokers; no history of drug or alcohol abuse Not reported Prenatal supplement including 5 mmol Ca 23 39 % Not reported Third trimester +
Pobocik et.al (2003) [38] Guam (USA Teritory) Cross-sectional study NA 434 14–20 Not reported Not reported Reported that any contribution from supplements was not included in analysis    24 h recall (single) Mean over pregnancy −/+
Rycel et.al (2009) [44] Poland Retro-spective cohort NA 102 15–18 Not reported Not reported none reported    Venous blood sample Before and after delivery −/+
Young et.al (2010) [29] USA Cross-sectional study NA 92 14–18 Healthy, singleton pregnancy HIV, diabetes, pre-eclampsia, eating disorders, malabsorption diseases, self-reported drug use Prenatal supplement including 27 mg iron 92 Not reported Venous blood sample Second trimester and delivery +
Young et.al (2012) [30] USA Cross-sectional study NA 171 Under 18 (mean 17.1) Healthy, singleton pregnancy HIV, diabetes, pre-eclampsia, eating disorders, malabsorption diseases 400 IU Vitamin D supplement given to participants found to be deficient 46 (estimated from reported percentages) 26.4 % - daily, 35.8 % at least twice per week 10 ml venous blood sample Delivery +
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BMC Pregnancy and Childbirth

ISSN: 1471-2393

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