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Study Title and Description

Caffeine and miscarriage risk.



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 and miscarriage risk.
Author DA Savitz,RL Chan,AH Herring,PP Howards,KE Hartmann,
Country
Year 2008
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 18091004
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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 examined the relationship of coffee and caffeine intake with clinically-recognized pregnancy loss prior to 20 weeks’ completed gestation, using a discrete-time continuation ratio logistic survival model.
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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) Pregnant women at < 12 weeks’ gestation were recruited, also women aged 18 to 45 who were trying to conceive for </=6 months were identified and enrolled if they became pregnant. Once pregnant, women were interviewed by telephone before 16 weeks’ gestation. An endovaginal ultrasound was performed if possible before 8 weeks’ gestation to date the pregnancy and assess fetal viability. Miscarriage was defined as loss of a clinically recognized pregnancy at or before 20 completed weeks’ gestation from last menstrual period (LMP). We relied on self-reported LMP to define gestational age. Pregnancy outcomes were identified through self-report during follow-up and were confirmed by medical records or by vital records for live births and fetal deaths after 20 weeks’ gestation. We inquired about caffeinated (brewed and instant) coffee, caffeinated (iced and hot) tea, and caffeinated soda consumption, including the number and size of cups consumed per day. We assigned cups of coffee and hot tea as small (4–10 oz), medium (12–14 oz), and large (16–24 oz). Iced tea was categorized as small (4–10 oz), medium (12–20 oz), and large (22–34 oz), and sodas as small (8–12 oz), medium (14–22 oz), and large (24–34 oz). Reported daily consumption of less than one cup or glass was set to half of a small cup. We assigned caffeine content to each caffeinated beverage (REVIEWER NOTE: paper notes reference for content but does not list actual amounts). We considered 3 time points of caffeine exposure: Prepregnancy exposure; 4 weeks after LMP (after any changes associated with planning pregnancy) and current consumption at the time of the interview (or when still pregnant, for women who experienced losses). We used a discrete-time continuation ratio logistic survival model to estimate week-specific odds ratios for the probability of having a miscarriage in a given week, conditional on a woman still being pregnant at the beginning of that week. Coffee and caffeine consumption at each of the 3 time points was divided into 3 groups: none, less than or equal to the median among consumers at that time point, and above the median. In separate models, we compared those >75th percentile among consumers with those who consumed none.
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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) Miscarriage (SA)
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List additional health endpoints (separately).
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List additional health endpoints (separately)
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Notes Miscarriage defined as loss of a clinically recognized pregnancy at or before 20 completed weeks’ gestation from last menstrual period (LMP).
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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 Pregnancy outcomes were identified through self-report during follow-up and were confirmed by medical records or by vital records for live births and fetal deaths after 20 weeks’ gestation.
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Caffeine (general) Caffeine (general)
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Coffee Coffee
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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 consumption at each of the 3 time points was divided into 3 groups: none, less than or equal to the median among consumers at that time point, and above the median. In separate models, we compared those > 75th percentile among consumers with those who consumed none. Prepregnancy mg/day: 0, >0-<243.7, >/=243.7 (and >513.2) 4 wk post-LM mg/day: 0, >0-<210.3, >/=210.3 (and >463.1) ~16 weeks gestation mg/day: 0, >0-<144.3, >/= 144.3 (and >273.2)
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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) Potential confounders included maternal age, race/ethnicity, education, marital status, income, smoking, alcohol use, body mass index, age at menarche, employment status, diabetes, miscarriage history, induced abortion history, vitamin use, and nausea and vomiting in early pregnancy.
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Provide a general description of results (as reported by the authors). Among all women, coffee and caffeine consumption at all 3 time points were unrelated to the overall risk of miscarriage , with all adjusted odds ratios between 0.7 and 1.3. Analyses of losses before the interview, for whom there is greater susceptibility to biased reporting of exposure, yielded evidence of a positive association with coffee and caffeine exposure around the time of the interview, but the results were imprecise. When analyses were restricted to losses after the interview, the results were uniformly close to the null except for a single, imprecise measure
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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? There is little indication of possible harmful effects of caffeine on miscarriage risk within the range of coffee and caffeine consumption reported, with a suggested reporting bias among women with losses before the interview. The results may reflect exposure misclassification and unmeasured heterogeneity of pregnancy losses.
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What were the sources of funding? Supported by the American Water Works Association Research Foundation under Contract 2579 and in part by the Intramural Research Program of the NIH, National Institute of Child Health and Human Development, and the National Institute of Environmental Health Sciences (training grant ES07018).
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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.  SA/miscarriage NOAEL = >273.2 mg/day
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Notes regarding selection/listing of endpoints and exposures/doses to be compared to Nawrot. Analysis for all pregnancy loss and using intake reported ~16 weeks was selected as it represents the time during pregnancy. Although not part of the survival model, the adjusted OR for >75th percentile (>273.2 mg/day) was compared to 0 intake and thus selected. OR = 1.3, 95% CI 0.9, 1.9.
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What is the importance of the study with respect to the adverseness of the outcome? Critcal
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