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Study Title and Description

Maternal caffeine intake, blood pressure, and the risk of hypertensive complications during pregnancy. The Generation R 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 Maternal caffeine intake, blood pressure, and the risk of hypertensive complications during pregnancy. The Generation R Study.
Author R Bakker,EA Steegers,H Raat,A Hofman,VW Jaddoe,
Country
Year 2011
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 21164492
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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 associations of habitual caffeine intake in different periods of pregnancy with repeatedly measured blood pressure levels and the risks of pregnancy-induced hypertension and pre-eclampsia in a population-based prospective cohort study among 7,890 pregnant women.
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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) This study was embedded in the Generation R Study. Enrollment was aimed in early pregnancy (gestational age <18.0 weeks) at the routine fetal ultrasound examination but was allowed until birth of the child. In total, 6,691 women were enrolled before a gestational age of 18 weeks. In each trimester caffeine intake and systolic and diastolic blood pressure (Omron 907 automated digital oscillometric sphygmanometer (OMRON Healthcare Europe, Hoofddorp, the Netherlands),) were assessed by questionnaires and physical examinations, respectively. Information about maternal caffeine intake was obtained by postal questionnaires in each trimester of pregnancy. Response rates for these questionnaires were 91, 80, and 77%, respectively. Women who reported any coffee or tea drinking were asked to categorize their average number of cups of coffee or tea per day, and what type of coffee or tea they consumed (caffeinated, caffeinated and decaffeinated, or decaffeinated). According to standard values for caffeine content, a regular coffee serving (125 ml) in the Netherlands contains about 90 mg of caffeine, decaffeinated coffee contains about 3 mg, and tea contains about 45 mg.16 To calculate total caffeine intake in each trimester, we weighted the type of coffee or tea (caffeinated coffee = 1; caffeinated and decaffeinated coffee = 0.5; decaffeinated coffee = 0; caffeinated tea = 0.5; caffeinated and decaffeinated tea = 0.25; decaffeinated tea = 0; herbal tea = 0; green tea = 0.5). Thus, in our analyses each unit of caffeine intake reflects caffeine exposure based on one cup of caffeinated coffee (90 mg caffeine). Information about hypertensive complications was obtained from medical records. The following criteria were used to identify women with pregnancy-induced hypertension: development of systolic blood pressure ≥140 mm Hg and/or diastolic blood pressure ≥90 mm Hg after 20 weeks of gestation in previously normotensive women. These criteria plus the presence of proteinuria (defined as two or more dipstick readings of 2+ or greater, one catheter sample reading of 1+ or greater, or a 24-h urine collection containing at least 300 mg of protein) were used to identify women with pre-eclampsia. First, the associations of caffeine intake during pregnancy with repeatedly measured systolic and diastolic blood pressure were analyzed using unbalanced repeated measurement regression analyses. Second, the cross-sectional associations of maternal caffeine intake with blood pressure in first, second, and third trimester were assessed using multiple linear regression models. Third, the associations of maternal caffeine intake with hypertensive pregnancy complications were assessed using multiple logistic regression models
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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) Pregnancy-induced hypertension; pre-eclampsia
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List additional health endpoints (separately).
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List additional health endpoints (separately)
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Notes The following criteria were used to identify women with pregnancy-induced hypertension: development of systolic blood pressure ≥140 mm Hg and/or diastolic blood pressure ≥90 mm Hg after 20 weeks of gestation in previously normotensive women. These criteria plus the presence of proteinuria (defined as two or more dipstick readings of 2+ or greater, one catheter sample reading of 1+ or greater, or a 24-h urine collection containing at least 300 mg of protein) were used to identify women with pre-eclampsia.
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Clinical Clinical
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Physiological 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 Information on pregnancy complications was obtained from medical records. Women suspected of pregnancy complications based on these records were crosschecked with the original hospital charts.
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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.) Units caffeine/day: <2, 2-3.9, 4-5.9, >/=6 (note: 1 unit = 90 mg)
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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 body mass index at enrolment, height, maternal age at enrolment, ethnicity, educational level, parity, alcohol consumption, smoking habits, folic acid supplement use, total daily energy intake, and stress in pregnancy.
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Provide a general description of results (as reported by the authors). As compared to women using <2 units/day, we observed no differences in systolic and diastolic blood pressure levels for both the time-independent (intercept) and time-dependent (change in blood pressure with advancing gestational age) estimates for women who had more caffeine consumptions per day. In the cross-sectional analyses, higher caffeine intake tended to be associated with elevated systolic blood pressure levels in first and third trimester (P for trend <0.05), but not in second trimester. We found an increase in systolic blood pressure among the women who consumed between 4 and 5.9 units/day (1.17 mm Hg (95% confidence interval: 0.62, 2.81)) in third trimester, compared to women consumed <2 units of caffeine per day. Furthermore, no associations or trends were found in the cross-sectional analyses focused on the associations of caffeine intake with diastolic blood pressure. We observed no associations of higher caffeine levels with the risk of pregnancy-induced hypertension. As compared to women with caffeine intake of <2 units/ day, those daily consuming 2–3.9 units of caffeine had a lower risk of pre-eclampsia (odds ratio of 0.63 (95% confidence interval: 0.40, 0.96)), but no associations were observed for higher caffeine levels.
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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? In the cross-sectional analyses, higher caffeine intake tended to be associated with elevated systolic blood pressure levels in first and third trimester (P for trend <0.05), but not in second trimester. We found an increase in systolic blood pressure among the women who consumed between 4 and 5.9 units/day (1.17 mm Hg (95% confidence interval: 0.62, 2.81)) in third trimester, compared to women consumed <2 units of caffeine per day. Furthermore, no associations or trends were found in the cross-sectional analyses focused on the associations of caffeine intake with diastolic blood pressure. We observed no associations of higher caffeine levels with the risk of pregnancy-induced hypertension (p for trend = 0.593). As compared to women with caffeine intake of <2 units/ day, those daily consuming 2–3.9 units of caffeine had a lower risk of pre-eclampsia (odds ratio of 0.63 (95% confidence interval: 0.40, 0.96)), but no associations were observed for higher caffeine levels (p for trend = 0.382).
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What were the author's conclusions? In conclusion, our results suggest that caffeine intake during pregnancy seems to be associated with higher systolic blood pressure levels in first and third trimester, but not with diastolic blood pressure levels. We did not find evidence of significant adverse associations of caffeine intake on maternal cardiovascular adaptations during pregnancy. The unexpected finding of a possible protective association with moderate caffeine intake deserves further investigation.
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What were the sources of funding? The general design of Generation R Study is made possible by financial support from the Erasmus Medical Center, Rotterdam, the Erasmus University Rotterdam, the Netherlands Organization for Health Research and Development (ZonMw), the Netherlands Organization for Scientific Research (NWO), the Ministry of Health, Welfare and Sport and the Ministry of Youth and Families. V.W.V.J. received additional grants from the Netherlands Organization for Health Research and Development (ZonMw 90700303, 916.10159).
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What conflicts of interest were reported? The authors declared no conflict 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.  Pregnancy-induced hypertension and/or pre-eclampsia NOAEL = >/=540 mg/day
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Notes regarding selection/listing of endpoints and exposures/doses to be compared to Nawrot. Pregnancy-induced hypertension: OR = 0.95 (0.79-1.15) Pre-eclampsia: OR = 0.88 (0.67-1.17) Pregnancy-induced hypertensions + pre-eclampsia: OR = 0.93 (0.80-1.09) 1 unit = 90 mg/day caffeine
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What is the importance of the study with respect to the adverseness of the outcome? Critcal
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