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Study Title and Description

Risks of repeated miscarriage.



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 Risks of repeated miscarriage.
Author L George,F Granath,AL Johansson,B Olander,S Cnattingius,
Country
Year 2006
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 16466430
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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)? In the present investigation, we used information from a population-based case–control study to investigate the association between sociodemographic and anthropometric factors, obstetric history and life-style factors, with respect to the risks of two consecutive first-trimester miscarriages.
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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) The original case–control study on risk factors for miscarriage was conducted in Uppsala County, Sweden, from January 1996 to December 1998. Cases of first-trimester miscarriage (6–12 completed weeks of gestation) were identified, n = 108. Pregnancies had been confirmed by a positive human chorionic gonadotropin test. Controls for the original study were selected from pregnant women seeking prenatal care in Uppsala County, n = 583. Controls were matched to the cases by completed weeks of gestation. Three specially trained midwives conducted in-person interviews with cases and controls. Ninety per cent of the cases were interviewed within 2 weeks after their miscarriage diagnosis, and the remaining 10% were interviewed within 6 weeks. All controls were interviewed within 6 days after their last completed week of gestation used in matching. Women were also asked to report intake of various caffeine sources during each week of pregnancy, starting 4 weeks before the last menstrual period and ending in the most recently completed week of gestation. Sources of caffeine included coffee (brewed, boiled, instant and decaffeinated), tea (loose tea, tea bags and herbal tea), cocoa, chocolate, soft drinks and caffeine containing medications. Respondents were offered four cup sizes from which to choose (1.0, 1.5, 2.0 and 3.0 dL). Weekly consumption of soft drinks was estimated by the women in centiliters. The intake of caffeine was estimated using the following conversion factors; for 150 mL of coffee, 115 mg of caffeine if it was brewed, 90 mg if boiled, and 60 mg if instant; for 150 mL of tea, 39 mg if it was loose tea or tea bag and 0 mg if herbal tea; for 150 mL of soft drinks (cola), 15 mg; for 150 mL of cocoa, 4 mg; and for 1 g of chocolate (bar), 0.3 mg. data were analyzed with the use of conditional logistic regression analysis; odds ratios (OR) with 95% confidence intervals [CI] were used to estimate the relative risk.
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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) Repeated pregnancy loss
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List additional health endpoints (separately).
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List additional health endpoints (separately)
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Notes For cases, the last two pregnancies ended in miscarriages between 6 and 12 gestational weeks.
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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? Case-Control
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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 Pregnancies had been confirmed by a positive human chorionic gonadotropin test
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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.) Mean caffeine: 0-99,100-299, >/=300 mg/day
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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) Variables were included in the multivariable analyses if they were judged a priori to be associated with the risk of miscarriage, or if they were associated with the risk of repeated miscarriage in the crude analysis (P<0.05). The following variables were included: maternal age, obstetric history, induced abortions, myoma, time to conceive, marital status, smoking status, caffeine and alcohol intake during pregnancy, and plasma folate levels.
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Provide a general description of results (as reported by the authors). Caffeine intake was associated with a non-significant dose-dependent increase in risk of repeated miscarriage; caffeine ingestion increased the risk of miscarriage among non-smokers, but not among smokers.
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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? Caffeine intake was associated with a non-significant dose-dependent increase in risk of repeated miscarriage. Consistent with our previous study of a single miscarriage, we found that the caffeine-related increase in the risk of repeated miscarriage may be restricted to non-smokers. power because of small sample size.
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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, and by grants from the Swedish Council for Forestry and Agricultural Research (project 50.0292/00), and the Swedish Research Council (project K2001-27GX-14081-01).
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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 = >/=300 mg/day
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Notes regarding selection/listing of endpoints and exposures/doses to be compared to Nawrot. The intake of caffeine was estimated using the following conversion factors; for 150 mL of coffee, 115 mg of caffeine if it was brewed, 90 mg if boiled, and 60 mg if instant; for 150 mL of tea, 39 mg if it was loose tea or tea bag and 0 mg if herbal tea; for 150 mL of soft drinks (cola), 15 mg; for 150 mL of cocoa, 4 mg; and for 1 g of chocolate (bar), 0.3 mg. Mean caffeine, adjusted OR, 95% CI 0-99 1.0 Reference 100-299 1.6, 0.7, 3.3 >/=300 mg/day 1.8, 0.8, 3.9
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What is the importance of the study with respect to the adverseness of the outcome? Critcal
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