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Study Title and Description

Risk factors for first trimester miscarriage--results from a UK-population-based case-control study.



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 Risk factors for first trimester miscarriage--results from a UK-population-based case-control study.
Author N Maconochie,P Doyle,S Prior,R Simmons,
Country
Year 2007
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 17305901
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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)? The aim of this study was to examine the association between biological, behavioural and lifestyle risk factors and risk of miscarriage.
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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) Case–control study nested within a population-based, two-stage postal survey of reproductive histories of women randomly sampled from the UK electoral register. Six hundred and three women aged 18–55 years whose most recent pregnancy had ended in first trimester miscarriage (<13 weeks of gestation; cases) and 6116 women aged 18–55 years whose most recent pregnancy had progressed beyond 12 weeks (controls). Outcome was first trimester miscarriage. Cases were all women whose most recent pregnancy resulted in a first trimester miscarriage (<13 completed weeks) or, if the most recent pregnancy did not result in miscarriage, who had had a miscarriage since 1995. Controls were all women whose most recent pregnancy (including pregnancies current at the time of survey) went beyond 13 weeks of gestation. Caffeine (tea, coffee, caffeinated drinks) data were requested in relation to two time periods, the 3 months prior to conception and the first 12 weeks of pregnancy. The association between miscarriage and each risk factor was explored using logistic regression analysis, effects on risk being estimated by odds ratios with 95% confidence intervals.
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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) SA (miscarriage)
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List additional health endpoints (separately).
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List additional health endpoints (separately)
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Notes First trimester only
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Clinical Clinical
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Physiological
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Other 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? Both
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Optional: Name of Method or short description self-reported
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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 mg/day: 0, <151, 151-300, 301-500, >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) Adjusted for year of conception, maternal age, previous miscarriage and previous live birth - also nausea
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Provide a general description of results (as reported by the authors). When adjusted for maternal age, year of conception, previous miscarriage and previous live birth, there was a strong trend of increasing odds of miscarriage with increasing daily caffeine consumption (P = 0.0003 for trend). However, the effect of caffeine was almost entirely due to the effect of nausea (women who felt sick did not tend to drink coffee, the main source of caffeine), and after adjusting for nausea, the effect of caffeine disappeared (P = 0.67). OR for >500 mg/day = 1.14 (0.79-1.66).
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Did the authors perform a dose-response analysis (or trend/related analysis)? Yes
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What were the authors's observations re: trend analysis? When adjusted for maternal age, year of conception, previous miscarriage and previous live birth, there was a strong trend of increasing odds of miscarriage with increasing daily caffeine consumption (P = 0.0003 for trend). However, the effect of caffeine was almost entirely due to the effect of nausea (women who felt sick did not tend to drink coffee, the main source of caffeine), and after adjusting for nausea, the effect of caffeine disappeared (P = 0.67).
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What were the author's conclusions? After adjustment for nausea, we did not confirm an association with caffeine consumption. The results confirm that advice to encourage a healthy diet, reduce stress and promote emotional wellbeing might help women in early pregnancy (or planning a pregnancy) reduce their risk of miscarriage. Findings of increased risk associated with previous termination, stress, change of partner and low pre-pregnancy weight are noteworthy, and we recommend further work to confirm these findings in other study populations.
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What were the sources of funding? The project was funded by the National Lottery Community Fund (through the Miscarriage Association) and by the Miscarriage 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.  SA (miscarriage): NOAEL = >500 mg/day
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Notes regarding selection/listing of endpoints and exposures/doses to be compared to Nawrot. Most refined analysis was selected, adjusted for nausea. ORs not adjusted for nausea, but for other confouders suggested the LOAEL to be 301-500 mg/day (OR = 1.51, CI 1.06-2.71).
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What is the importance of the study with respect to the adverseness of the outcome? Critcal
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