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Study Title and Description

Coffee and fetal death: a cohort study with prospective data.



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 Coffee and fetal death: a cohort study with prospective data.
Author BH Bech,EA Nohr,M Vaeth,TB Henriksen,J Olsen,
Country
Year 2005
Numbers

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


Extraction Form: Reproductive Toxicity - Design Details
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Design Details
Question... Follow Up Answer Follow-up Answer
Refid 16207803
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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)? Our aim in this study was to evaluate the association between coffee consumption during pregnancy and the risk of fetal death, taking into account a number of potential confounders.
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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 study was carried out in the Danish National Birth Cohort; the final study population consisted of 88,482 pregnancies with 1,102 fetal deaths. At approximately 16 weeks gestation, the participants were asked, ‘‘How many cups of coffee do you drink daily?’’ Answers were coded in number of cups per day; a mugful was coded as two cups. Women with missing information on coffee consumption were excluded from the study (n = 32). Similar questions were asked about consumption of tea, while information on cola intake was gathered as none, < 1 liter/week, or >/= 1 liter/week. Livebirths and stillbirths were identified in the Civil Registration System and the Danish Medical Birth Registry. The main outcome in the study was fetal death, defined as either spontaneous abortion (gestational age < 196 days) or stillbirth (gestational age >/= 196 days). Information about gestational age was obtained from the National Hospital Discharge Register. We estimated relative risks of fetal death due to coffee intake as hazard ratios (with 95 percent confidence intervals) in Cox regression analysis with left-truncation and right-censoring. In the analysis, coffee intake was considered as a categorical variable (0, 0.5–3, 4–7, and >/= 8 cups/day) and as a continuous variable (number of cups per day) in a test for trend. We also analyzed the data according to caffeine intake itself by using average levels of 100 mg of caffeine for a cup of coffee and 50 mg for a cup of tea. We also analyzed causes of singleton stillbirth as the primary outcome in a separate Cox analysis (0, 0.5-3, and >/=4 cups/day).
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How many outcome-specific endpoints are evaluated? 2
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What is the (or one of the) endpoint(s) evaluated? (Each endpoint listed separately) Fetal death (late SA + stillbirth); stillbirth
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List additional health endpoints (separately).
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List additional health endpoints (separately)
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Notes spontaneous abortion (gestational age < 196 days) or stillbirth (gestational age >/= 196 days
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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 Livebirths and stillbirths were identified in the Civil Registration System and the Danish Medical Birth Registry
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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
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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.) Fetal death (late SA + stillbirth): coffee (0, 0.5–3, 4–7, and >/= 8 cups/day) and also converted to caffeine though data not shown. Stillbirth: coffee only (0, 0.5-3, and >/=4 cups/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) Fetal death (late SA + stillbirth): age, parity, smoking, prepregnancy body mass index, alcohol consumption, and socio-occupational status Stillbirth: age, parity, socio-occupational status, body mass index, smoking, and alcohol consumption
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Provide a general description of results (as reported by the authors). Women who drank eight or more cups of coffee per day had twice the risk of fetal death of women who did not drink coffee. After adjustment for potential confounders, the risk was attenuated but remained high (hazard ratio = 1.59, 95 percent confidence interval: 1.19, 2.13). The risk increased with increasing coffee intake (p. 0.001 for trend), with no statistically significant departure from linearity (p = 0.26). The association was most pronounced for late fetal deaths (deaths following 20 completed weeks’ gestation). However, we found no statistically significant interaction between coffee consumption and fetal death during specific periods of gestation (test for interaction: p = 0.45). When we repeated the analysis with entry times of 2–28 days after interview, the coffee-related risk of fetal death was further attenuated in all exposure groups and was no longer statistically significant, although the estimates pointed in the same direction. Using caffeine intake from both coffee and tea gave results identical to those for coffee alone. We found no association between consumption of tea or cola and fetal death (data not shown). We found that the risk of stillbirth due to placental dysfunction was increased among consumers of four or more cups or coffee per day (hazard ratio . 2.27, 95 percent confidence interval: 1.21, 4.28); all stillbirths were not associated.
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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? Fetal death (late SA + stillbirth): The risk increased with increasing coffee intake (p¼0.001 for trend), with no statistically significant departure from linearity (p =0.26). Still birth: no trend analysis noted
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What were the author's conclusions? Consumption of coffee during pregnancy was associated with a higher risk of fetal death, especially losses occurring after 20 completed weeks of gestation.
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What were the sources of funding? The Danish National Research Foundation (Copenhagen, Denmark) established the Danish Epidemiology Science Centre, which initiated and created the Danish National Birth Cohort. The cohort study received a major grant from this foundation. Additional support for the Danish National Birth Cohort is obtained from the Pharmacy Foundation (Copenhagen), the Egmont Foundation (Copenhagen), the March of Dimes Birth Defects Foundation (New York, New York), and the Augustinus Foundation (Copenhagen).
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What conflicts of interest were reported? "None declared"
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Does the exposure (dose) need to be standardized to the SR? Multiple metrics
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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). Fetal death (late SA + stillbirth): LOAEL = 4-7 cups/day Using author conversion: 4 cups/day x 100 mg/cup = 400 mg/day 7 cups/day x 100 mg/cup = 700 mg/day Standardizing to the SR: 4 cups/day x 95 mg/cup = 380 mg/day 7 cups/day x 95 mg/cup = 665 mg/day Stillbirth: NOAEL >/=4 cups/day 4 cups/day x 95 mg/cup = 380 mg/day
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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.  Fetal death (late SA + stillbirth): LOAEL = 400-700 mg/day Stillbirth: NOAEL >/= 380 mg/day caffeine
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Notes regarding selection/listing of endpoints and exposures/doses to be compared to Nawrot. For stillbirth, the authors do not report on caffeine content. For fetal death (late SA + stillbirth), the authors converted to caffeine as follows, 100 mg of caffeine for a cup of coffee and 50 mg for a cup of tea. They conducted the analyses and reported: "Using caffeine intake from both coffee and tea gave results identical to those for coffee alone. We found no association between consumption of tea or cola and fetal death (data not shown)." However, the amount of caffeine associated with each intake level was not reported either. Therefore, we opted to calculate using the authors conversation rates. When converting to standardize to the SR, the outcome did not differ by much and would not change the outcome relative to the PECO: 4 cups/day x 100 mg/cup = 400 mg/day 7 cups/day x 100 mg/cup = 700 mg/day
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What is the importance of the study with respect to the adverseness of the outcome? Critcal
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