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Study Title and Description

Caffeine consumption during pregnancy and risk of preterm birth: a meta-analysis.



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 Caffeine consumption during pregnancy and risk of preterm birth: a meta-analysis.
Author E Maslova,S Bhattacharya,SW Lin,KB Michels,
Country
Year 2010
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 20844077
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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)? Here, we systematically reviewed all available epidemiologic evidence and conducted a meta-analysis on the association between maternal caffeine consumption during pregnancy and the risk of preterm birth.
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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) We followed the MOOSE consensus statement for conducting a meta-analysis of observational studies. We searched MEDLINE and EMBASE articles published between 1966 and July 2010, cross-referenced reference lists of the retrieved articles, and identified 15 cohort and 7 case-control studies that met inclusion criteria for this meta-analysis. We included case-control and cohort studies with coffee, tea, cocoa/chocolate, and cola or soda drinks as the sources of caffeine exposure. The outcome was defined as birth before 37 wk of gestation. Literature reviews, case reports, animal studies, or studies examining only low birth weight or specific obstetric complications were excluded. Also excluded were studies with inadequate information on amount or source of caffeine intake, no control subjects, or no measures of association that could be extracted or derived. We conducted separate meta-analyses comparing different levels of consumption with the lowest level/ no caffeine intake and by trimester. We classified exposure according to 5 categories based on the provided or converted consumption levels. For example, the lowest category (reference category) contained the lowest intake reported by the studies, ranging from 0 to <400 mg/d, and the highest category included the highest intake reported, ranging from any caffeine consumption to >/=1330 mg/d. Because we used the categories reported by the studies, these categories were not mutually exclusive. Given a high variability across categories of caffeine intake, we conducted sensitivity analyses, limiting the highest category of caffeine consumption to >/=300 mg/d. Quality assessment included examination of publication bias and sources of heterogeneity.
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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) Preterm birth
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List additional health endpoints (separately).
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List additional health endpoints (separately)
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Notes defined as birth before 37 wk of gestation.
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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? Meta-analysis
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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
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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
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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 mg/day: 0-<400, >/= 300
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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) Not addressed in meta-analysis
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Provide a general description of results (as reported by the authors). We included case-control and cohort studies with coffee, tea, cocoa/chocolate, and cola or soda drinks as the sources of caffeine exposure. The outcome was defined as birth before 37 wk of gestation. The overall effect estimates from a comparison of the highest caffeine consumption category with the lowest category in the first, second, and third trimesters in cohort studies were 1.11 (95% CI: 0.96, 1.28; P = 0.15), 1.10 (95% CI: 1.01, 1.19; P = 0.02), and 1.08 (95% CI: 0.93, 1.27; P = 0.32), respectively. The combined effect estimates in case-control studies during the first, second, and third trimesters were 1.04 (95% CI: 0.84, 1.37; P = 0.60), 1.17 (95% CI: 0.94, 1.45; P = 0.17), and 0.94 (95% CI: 0.79, 1.12; P = 0.46), respectively. Analyses that limited the highest intake to >/=300 mg/d (8, 9, 29, 31, 33, 35–39) resulted in combined effect estimates for the cohort studies that were similar to those observed in the original analysis. For case-control studies, limiting the highest intake to >/=300 mg/d (26, 44–46) shifted the association in the inverse direction for all trimesters: first (0.70; 95% CI: 0.47, 1.04), second (0.57; 95% CI: 0.35, 0.91), and third (0.53; 95% CI: 0.32, 0.87).
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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? In this meta-analysis of 15 cohort and 7 case-control studies, we found no important association between maternal caffeine consumption during pregnancy and the risk of preterm birth.
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What were the sources of funding? There were no funding sources for this work. S-WL was funded by the Cancer Prevention Fellowship Program, National Institutes of Health, Bethesda, MD. SB was funded by a postdoctoral fellowship at the Institute of Molecular Medicine at the University of Texas Health Science Center, Houston, TX.
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What conflicts of interest were reported? None of the authors had any personal or financial conflicts of interest
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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.  Preterm birth: NOAEL = >/=300 mg/day
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Notes regarding selection/listing of endpoints and exposures/doses to be compared to Nawrot. The effect level was derived from the analysis that limited high intake to >/=300 mg/day, rather than the larger analysis that included any to >/=1330 mg/day. The ORs for cohort studies will be used from the larger analysis; ORs for the limited analysis were provided for case-control studies.
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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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Adverse Events
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