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Table 1 Characteristics of prospective studies on caffeine intake in relation to low birth weight

From: Maternal caffeine intake during pregnancy is associated with risk of low birth weight: a systematic review and dose-response meta-analysis

First author, year Country Study design Number of cases Total number Age Exposure Method of exposure assessment Period of exposure assessed Outcome Adjustments
Martin, 1987 [30] United States Cohort 70 3,654 <30 y: 69% Caffeine Interviewer-administered questionnaire Early pregnancy Low birth weight Gestational age, ethnicity, parity, smoking
-30 y: 31%
Olsen, 1991 [27] Denmark Cohort 391 11,591 <30 y: 71% Coffee Self-administered questionnaire First to second trimester Low birth weight Smoking, social group, parity, alcohol intake (did not adjust maternal age for this outcome but did for birth weight)
-30 y: 29%
Mills, 1993 [23] United States Cohort 21 352 <30 y: 48% Caffeine Interview First, third trimesters and over the whole pregnancya Low birth weighta, intrauterine growth restriction Maternal age, income, education, pre-pregnancy weight, height, ethnicity, parity, smoking and alcohol intake
-30 y: 52%
Spinillo, 1994 [28] Italy Nested case-control 347 1,041 Case mean: 27.4 y Coffee NA Variable, asked at prenatal visit or at delivery Intrauterine growth restriction Smoking, maternal age, marital status, parity, pre-pregnancy weight, BMI, weight gain, previous low birth weight, fetal sex, 1st trimester hemorrhage, hypertension, education, social class, alcohol intake
Control mean: 29.3 y
Grosso, 2001 [31] United States Cohort 189 2,714 <30 y: 38% Caffeine Interviewer-administered questionnaire Before 16 weeks gestations Intrauterine growth restriction Smoking, height, antenatal weight gain, preeclampsia during index pregnancy, parity and bleeding during the third trimester.
-30 y: 62%
Bracken, 2003 [24] United States Cohort 108 2,291 <30 y: 47% Caffeine Interview First trimestera & third trimesterb Low birth weighta, intrauterine growth restriction Maternal age, parity, number of prior pregnancies, marital status, ethnicity, education, height, smoking during the third trimester and weight
-30 y: 53%
CARE study group, 2008 [6] United Kingdom Cohort 343 2,635 Mean 30.0 y Caffeine Interviewer-administered questionnaire (validated) First, second, third trimesters and over the whole pregnancya Intrauterine growth restriction Maternal age, weight, height, ethnicity, parity, neonatal gestational age at delivery and sex, smoking and alcohol intake
Bakker, 2010 [25] The Netherlands Cohort 331 7,346 Mean 29.7 y Caffeine Self-administered questionnaire (postal) Third trimester Low birth weighta, Small for gestational age Gestational age at visit, maternal age, education, ethnicity, parity, smoking, alcohol intake, height, BMI at intake, nutritional intake, folic acid supplement use, maternal pregnancy complications and fetal sex
Sengpiel, 2013 [9] Norway Cohort 4,503 59,123 <30 y: 46% Caffeine Self-administered FFQ (validated) First to second trimester Small for gestational age Maternal age, pre-pregnancy BMI, parity, history of preterm delivery, fetal sex, nausea during second trimester, smoking, passive smoking, nicotine intake from other sources, alcohol intake, energy intake, maternal education, marital status and household income
-30 y: 54%
  1. adata used for the main analysis; bdata not used because they were collected postnatally (after the occurrence of outcome). BMI, body mass index; FFQ, food frequency questionnaire; NA, not available; y, year.