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Study Title and Description

Effect of caffeine exposure during pregnancy on birth weight and gestational age.



Key Questions Addressed
1 For [population], is caffeine intake above [exposure dose], compared to intakes [exposure dose] or less, associated with adverse effects on reproductive and developmental outcomes?
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Primary Publication Information
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TitleData
Title Effect of caffeine exposure during pregnancy on birth weight and gestational age.
Author B Clausson,F Granath,A Ekbom,S Lundgren,A Nordmark,LB Signorello,S Cnattingius,
Country
Year 2002
Numbers

Secondary Publication Information
There are currently no secondary publications defined for this study.


Extraction Form: Reproductive Toxicity - Design Details
Arms
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Design Details
Question... Follow Up Answer Follow-up Answer
Refid 11867354
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What outcome is being evaluated in this paper? Reproductive and Development
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What is the objective of the study (as reported by the authors)? We conducted a population-based, prospective study of the effect of caffeine on birth weight, gestational age, and birth weight standarized for gestational age (birth weight ratio), in which caffeine consumption was selfreported during in-person interviews twice during pregnancy. We also collected detailed information on potentially confounding factors, including smoking (as measured by plasma cotinine levels) and pregnancy symptoms.
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Provide a general description of the methods as reported by the authors. Information should be extracted based on relevance to the SR (i.e., caffeine related methods) Prospective, population-based cohort study of 873 singleton pregnancies. Caffeine exposures were ascertained from in-person interviews by midwives at 6–12 and 32–34 completed gestational weeks. Caffeine sources included coffee (brewed, boiled, instant, and decaffeinated), tea (loose, tea bags, and herbal), cocoa, chocolate, soft drinks, and caffeine-ontaining medications. Respondents were offered four cup sizes (1 dl, 1.5 dl, 2 dl, 3 dl) from which to choose. Weekly soft drink intake in centiliters was estimated by the participants. Caffeine intake was estimated using the following conversion factors: 150 ml of coffee: brewed = 115 mg, boiled= 90 mg, and instant coffee = 60 mg; 150 ml of loose tea or tea bags = 39 mg (herbal tea = 0 mg); 150 ml of soft cola drinks= 15 mg; 150 ml of cocoa = 4 mg; 1 g of a chocolate bar = 0.3 mg; and a few drugs contained 50–100 mg of caffeine per tablet. Outcomes were birth weight (in grams), gestational age (in completed days of gestation according to the second trimester ultrasound scan), and birth weight ratio (defined as a deviation from the expected gestation and sex-standardized birth weight, according to Swedish fetal growth standards). The birth weight ratio was calculated by standardizing the birth weight by subtracting the gestational age- and sex- specific expected weight and dividing by the standard deviation and, thereafter, applying a logarithmic transformation. Univariate associations between birth weight, gestational age, and the birth weight ratio and the potential risk factors were studied by one-way analysis of variance and are presented as the means and standard errors. In multivariate analyses, the models included the average caffeine intake during pregnancy, the cotinine levels in the third trimester, and all the variables presented in table 2. A post hoc power analysis showed that the study had 80 percent statistical power (at a 5 percent two-sided significance level) to detect the following differences between intake groups 0–99 mg per day and >300 mg per day: 169 g in birth weight, 3.6 days in gestational age, and 3.6 percent difference in birth weight ratio
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How many outcome-specific endpoints are evaluated? 1
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What is the (or one of the) endpoint(s) evaluated? (Each endpoint listed separately) Birth weight, birth weight ratio
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List additional health endpoints (separately).
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List additional health endpoints (separately)
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Notes Gestational age
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Clinical Clinical
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Physiological
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Other
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What is the study design? Cohort
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Randomized or Non-Randomized?
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What were the diagnostics or methods used to measure the outcome? Objective
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Optional: Name of Method or short description Outcomes were birth weight (in grams), gestational age (in completed days of gestation according to the second trimester ultrasound scan), and birth weight ratio (defined as a deviation from the expected gestation and sex-standardized birth weight, according to Swedish fetal growth standards).
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Caffeine (general) Caffeine (general)
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Coffee Coffee
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Chocolate Chocolate
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Energy drinks
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Gum
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Medicine/Supplement Medicine/Supplement
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Soda Soda
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Tea Tea
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Measured
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Self-report Self-report
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Children
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Adolescents
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Adults
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Pregnant Women Pregnant Women
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What was the reference, comparison, or control group(s)? (e.g. high vs low consumption, number of cups, etc.) Caffeine intake in mg/day: 0-99, 100-299, 300-499, >/=500
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What were the listed confounders or modifying factors as stated by the authors? (e.g. multi-variable components of models.  Copy from methods) Adjustments were made for all variables included in table 2 (age, height, body mass index, country of birth, parity, previous low birth weight infant (<2,500 g), education, work, nausea, vomiting, fatigue, diabetes, hypertensive disorders).
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Provide a general description of results (as reported by the authors). In univariate analysis, Caffeine exposure expressed as categories of mean daily consumption during the entire pregnancy or by trimester was not associated with any of the outcome variables. In multivariate analyses, caffeine intake was not associated with birth weight, gestational age, or birth weight ratio.
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Did the authors perform a dose-response analysis (or trend/related analysis)? No
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What were the authors's observations re: trend analysis?
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What were the author's conclusions? Our study finds no support for an association between moderate caffeine consumption during pregnancy and restricted fetal growth. These results do not support an association between moderate caffeine consumption and reduced birth weight, gestational age, or fetal growth.
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What were the sources of funding? Financial support was provided by the International Epidemiology Institute through a grant from the National Soft Drink Association.
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What conflicts of interest were reported? None reported
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Does the exposure (dose) need to be standardized to the SR? No
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Provide calculations/conversions for the exposure based on the decision tree in the guide (for all endpoints/exposure levels of interest).
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List all the endpoint(s) followed by the dose (mg) which will be used in comparison to Nawrot.  Characterize value as LOAEL/NOAEL, etc. if possible.  NOAEL = >/= 500 mg/day for birth weight (p=0.98), gestational age (p=0.880, and birth weight ratio (p=0.70).
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Notes regarding selection/listing of endpoints and exposures/doses to be compared to Nawrot. No differences in birth outcomes in relation to the mean daily caffeine consumption in separate trimesters were observed, so the mean daily caffeine consumption during pregnancy (i.e., from conception to 32–34 weeks of gestation) was used as the exposure variable in the multivariate models.
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What is the importance of the study with respect to the adverseness of the outcome? Critcal
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Baseline Characteristics
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Results & Comparisons

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