The associations of maternal caffeine consumption and nausea with spontaneous abortion

Relationship between maternal caffeine and coffee intake and pregnancy loss: A grading of recommendations assessment, development, and evaluation-assessed, dose-response meta-analysis of observational studies

Background

Numerous studies report an association between coffee or caffeine consumption and pregnancy loss; however, the nature and strength of this relationship have not been clearly established. Based on recent studies, our meta-analysis aimed to test whether a dose-response relationship between coffee or caffeine consumption and pregnancy loss exists.

Methods

We searched for articles in PubMed, Web of Science, and Scopus published until May 2022. Two independent reviewers extracted data and rated the quality of the evidence using the GRADE approach. We applied a random-effects, one-stage dose-response meta-analysis.

Results

A total of 34 articles (18 cohort studies and 16 case-control studies) were included in this review. Results showed a significantly higher risk of pregnancy loss for coffee consumption before (Pooled ES: 1.21; 95% CI: 1.01-1.43) and during pregnancy (Pooled ES: 1.26; 95% CI: 1.04-1.57), and for coffee consumption during pregnancy in case-control studies (Pooled ES: 1.20; 95% CI: 1.19-6.41). Findings from this meta-analysis demonstrated that caffeine intake during pregnancy was associated with a significantly higher risk of pregnancy loss in cohort (Pooled ES: 1.58; 95% CI: 1.23-2.01) and case-control studies (Pooled ES: 2.39; 95% CI: 1.69-3.37, P < 0.001), respectively. A dose-response analysis suggested that an increase of a cup of coffee per day during pregnancy was associated with 3% increased risk of pregnancy loss; 100 mg of caffeine per day during pregnancy was also associated with 14 and 26% increased risk of pregnancy loss in cohort and case-control studies, respectively. A non-linear dose-response association was observed between coffee intake and the risk of pregnancy loss.

Conclusion

This study confirms that coffee or caffeine consumption raises the risk of pregnancy loss. Researchers are encouraged to conduct more studies to explore the underlying mechanisms and active compounds in coffee and caffeine.

Systematic Review Registration

[www.crd.york.ac.uk/prospero/], identifier [CRD42021267731].

Maternal caffeine consumption and pregnancy outcomes: a narrative review with implications for advice to mothers and mothers-to-be

OBJECTIVES

Caffeine is a habit-forming substance consumed daily by the majority of pregnant women. Accordingly, it is important that women receive sound evidence-based advice about potential caffeine-related harm. This narrative review examines evidence of association between maternal caffeine consumption and negative pregnancy outcomes, and assesses whether current health advice concerning maternal caffeine consumption is soundly based.

METHODS

Database searches using terms linking caffeine and caffeinated beverages to pregnancy outcomes identified 1261 English language peer-reviewed articles. Screening yielded a total of 48 original observational studies and meta-analyses of maternal caffeine consumption published in the past two decades. The articles reported results for one or more of six major categories of negative pregnancy outcomes: miscarriage, stillbirth, low birth weight and/or small for gestational age, preterm birth, childhood acute leukaemia, and childhood overweight and obesity.

RESULTS

Of 42 separate sets of findings reported in 37 observational studies, 32 indicated significantly increased caffeine-related risk and 10 suggested no or inconclusive associations. Caffeine-related increased risk was reported with moderate to high levels of consistency for all pregnancy outcomes except preterm birth. Of 11 studies reporting 17 meta-analyses, there was unanimity among 14 analyses in finding maternal caffeine consumption to be associated with increased risk for the four outcome categories of miscarriage, stillbirth, low birth weight and/or small for gestational age, and childhood acute leukaemia. The three remaining meta-analyses were also unanimous in reporting absence of a reliable association between maternal caffeine consumption and preterm birth. No meta-analyses were identified for childhood overweight and obesity, although four of five original observational studies reported significant associations linking maternal caffeine consumption to that outcome category.

CONCLUSIONS

The substantial majority finding from observational studies and meta-analyses is that maternal caffeine consumption is reliably associated with major negative pregnancy outcomes. Reported findings were robust to threats from potential confounding and misclassification. Among both observational studies and meta-analyses, there were frequent reports of significant dose-response associations suggestive of causation, and frequent reports of no threshold of consumption below which associations were absent. Consequently, current evidence does not support health advice that assumes 'moderate' caffeine consumption during pregnancy is safe. On the contrary, the cumulative scientific evidence supports pregnant women and women contemplating pregnancy being advised to avoid caffeine.

Caffeine exposure during pregnancy: Is it safe?

Numerous studies have examined the association between maternal caffeine consumption and infant and childhood health outcomes and the results have been inconsistent. The study of maternal caffeine intake and infant and childhood health outcomes is prone to methodologic challenges. In this review, we examine the existing evidence juxtaposed with the epidemiologic design challenges that color the interpretation of the study results presented. In light of methodologic/interpretation challenges, it seems reasonable to infer that exposure to low levels of caffeine is probably not associated with substantial infant and childhood adversities. However, more research is needed using well designed studies that address methodologic challenges.

Maternal coffee intake and the risk of bleeding in early pregnancy: a cross-sectional analysis

BACKGROUND

Caffeine can easily cross the placenta, and maternal caffeine intake, thus, has an effect on fetal growth. However, it is still unclear whether coffee consumption is an independent risk factor for bleeding in early pregnancy. The objective of this study was to examine the association between pre-pregnancy coffee consumption patterns and the risk of bleeding in early pregnancy.

METHODS

A cross-sectional analysis was conducted among 3510 pregnant women from the Korean Pregnancy Outcome Study who underwent baseline examination and for whom the results of the pregnancy were available. Coffee consumption patterns before pregnancy were examined using a questionnaire. The participants were classified according to the frequency of coffee consumption into seldom (< 1 cup/week), light (< 1 cup/day), moderate (1 cup/day), and heavy coffee drinker (≥2 cups/day) groups. Bleeding in early pregnancy was defined as the occurrence of vaginal bleeding in the first 20 weeks of pregnancy. Multiple logistic regression models were applied to examine the association between pre-pregnancy coffee consumption and the risk of bleeding in early pregnancy, after adjusting for age, body mass index (BMI), systolic blood pressure, cigarette smoking and alcohol consumption behavior, previous and current physical activity levels, stress levels, history of depression, antenatal depressive symptoms during the first trimester, type of emesis, parity, and the number of livebirths, stillbirths, miscarriages, and abortions.

RESULTS

Women who were light, moderate, and heavy coffee drinkers before pregnancy had adjusted ORs of 1.086, 1.225, and 1.358, respectively, for bleeding in early pregnancy. In a fully adjusted model, heavy coffee drinkers showed a significantly higher risk of bleeding in early pregnancy, even in women aged 35 years and younger (OR 1.680) and in those with a normal body mass index (OR 1.389), who were at relatively low risk for pregnancy-related complications.

CONCLUSIONS

Our results showed that heavy coffee drinking was independently associated with a higher risk of bleeding in early pregnancy among pregnant Korean women, suggesting that caffeine intake before conception and during pregnancy should be reduced. Our study highlights the need for nutritional interventions for healthy coffee drinking among pregnant women in Korea.

Big Data Analytics in Healthcare

Sensors and mobile phones shine in the Big Data area due to their capabilities to retrieve a huge amount of real-time data; which was not possible previously. In the specific field of healthcare, we can now collect data related to human behavior and lifestyle for better understanding. This pushed us to benefit from such technologies for early miscarriage prediction. This research study proposes to combine the use of Big Data analytics and data mining models applied to smartphones real-time generated data. A K-means data mining algorithm is used for clustering the dataset and results are transmitted to pregnant woman to make quick decisions; with the intervention of her doctor; through an android mobile application that we created. As well, she receives recommendations based on her behavior. We used real-world data to validate the system and assess its performance and effectiveness. Experiments were made using the Big Data Platform Databricks.

Biases Inherent in Studies of Coffee Consumption in Early Pregnancy and the Risks of Subsequent Events

Consumption of coffee by women early in their pregnancy has been viewed as potentially increasing the risk of miscarriage, low birth weight, and childhood leukemias. Many of these reports of epidemiologic studies have not acknowledged the potential biases inherent in studying the relationship between early-pregnancy-coffee consumption and subsequent events. I discuss five of these biases, recall bias, misclassification, residual confounding, reverse causation, and publication bias. Each might account for claims that attribute adversities to early-pregnancy-coffee consumption. To what extent these biases can be avoided remains to be determined. As a minimum, these biases need to be acknowledged wherever they might account for what is reported.

Time-Varying Effects of Signs and Symptoms on Pregnancy Loss <20 Weeks: Findings from a Preconception Prospective Cohort Study

BACKGROUND

Although pregnancy loss affects one-third of pregnancies, the associated signs/symptoms have not been fully described. Given the dynamic nature of maternal physiologic adaptation to early pregnancy, we posited the relationships between signs/symptoms and subsequent loss would vary weekly.

METHODS

In a preconception cohort with daily follow-up, pregnancies were ascertained by self-administered sensitive home pregnancy tests on day of expected menses. We evaluated the effects of weekly time-varying signs/symptoms (including vaginal bleeding, lower abdominal cramping, and nausea and/or vomiting) on pregnancy loss <20 weeks in Cox proportional hazards models and calculated the week-specific probability of loss by the presence/absence of each sign/symptom.

RESULTS

Of 341 pregnancies ascertained by home pregnancy test, 95 (28%) ended in loss. Relationships between signs/symptoms and loss varied across time since first positive pregnancy test. In the first week following pregnancy confirmation, when many losses occurred, bleeding [hazard ratio (HR) 8.7, 95% confidence interval (CI) 4.7, 16.0] and cramping (HR 1.8, 95% CI 1.2, 2.7) were associated with loss even when accompanied by nausea and/or vomiting (HR 5.2, 95% CI 2.6, 10.5). After the second week, new relationships emerged with nausea and/or vomiting inversely associated (HR range 0.6-0.3, all 95% CI upper bounds <1.00) and bleeding no longer associated with loss. Probabilities of loss of ranged from 78% (95% CI 59%, 96%) with bleeding present in week 1 to 8% (95% CI 5%, 12%) with nausea/vomiting present in week 5.

CONCLUSIONS

Relationships between signs/symptoms and pregnancy loss vary in early pregnancy possibly reflecting maternal physiologic response.

Association between coffee or caffeine consumption and fecundity and fertility: a systematic review and dose-response meta-analysis

Objective

The aim was to investigate whether coffee or caffeine consumption is associated with reproductive endpoints among women with natural fertility (ie, time to pregnancy [TTP] and spontaneous abortion [SAB]) and among women in fertility treatment (ie, clinical pregnancy rate or live birth rate).

Design

This study was a systematic review and dose-response meta-analysis including data from case-control and cohort studies.

Methods

An extensive literature search was conducted in MEDLINE and Embase, with no time and language restrictions. Also, reference lists were searched manually. Two independent reviewers assessed the manuscript quality using the Newcastle-Ottawa Scale (NOS). A two-stage dose-response meta-analysis was applied to assess a potential association between coffee/caffeine consumption and the outcomes: TTP, SAB, clinical pregnancy, and live birth. Heterogeneity between studies was assessed using Cochrane Q-test and I² statistics. Publication bias was assessed using Egger's regression test.

Results

The pooled results showed that coffee/caffeine consumption is associated with a significantly increased risk of SAB for 300 mg caffeine/day (relative risk [RR]: 1.37, 95% confidence interval [95% CI]: 1.19; 1.57) and for 600 mg caffeine/day (RR: 2.32, 95% CI: 1.62; 3.31). No association was found between coffee/caffeine consumption and outcomes of fertility treatment (based on two studies). No clear association was found between exposure to coffee/caffeine and natural fertility as measured by fecundability odds ratio (based on three studies) or waiting TTP (based on two studies).

Conclusion

Results from this meta-analysis support the growing evidence of an association between coffee/caffeine intake and the risk of SAB. However, viewing the reproductive capacity in a broader perspective, there seems to be little, if any, association between coffee/caffeine consumption and fecundity. In general, results from this study are supportive of a precautionary principle advised by health organizations such as European Food Safety Authority (EFSA) and World Health Organization (WHO), although the advised limit of a maximum of two to three cups of coffee/200-300 mg caffeine per day may be too high.

Signs and Symptoms of Early Pregnancy Loss

Approximately one-third of pregnancies end in loss; however, the natural history of early pregnancy loss, including signs and symptoms preceding loss, has yet to be fully described and its underlying mechanisms fully understood. We searched PubMed/MEDLINE and Embase to identify articles with prospective ascertainment of signs and symptoms, including vaginal bleeding, nausea, and vomiting, of pregnancy loss < 20 weeks gestation in spontaneous conceptions to ascertain existing literature on symptomatology of pregnancy loss. Two preconception and 16 pregnancy cohort studies that ascertained information on bleeding and/or nausea/vomiting prior to pregnancy loss ascertainment were included. Data from these studies indicated increased risk of loss with vaginal bleeding and decreased risk of loss with nausea/vomiting, though these studies were mostly comprised of pregnancies surviving into late first trimester. While such associations are biologically plausible, these study designs are subject to bias, given recruitment of women at later gestational ages and reliance on women presenting to care. Reporting symptoms to clinicians and over long periods may introduce reporting error. Data gaps remain regarding (1) relationships between signs and symptoms and losses occurring very early, prior to care entry; (2) empirical testing of whether relationships between signs and symptoms and loss differ across gestational age; (3) whether similar relationships between signs and symptoms and loss are observed in populations using assisted reproductive technologies; (4) the patterning of multiple signs and symptoms in relation to loss; and (5) how hormonal and physiologic adaptions to early pregnancy relate to symptomatology and pregnancy loss.

Pre-pregnancy caffeine and caffeinated beverage intake and risk of spontaneous abortion

PURPOSE

To investigate the relation between pre-pregnancy caffeine and caffeinated beverage intake and risk of spontaneous abortion (SAB).

METHODS

Our prospective cohort study included 15,590 pregnancies from 11,072 women with no history of SAB in the Nurses' Health Study II (1991-2009). Beverage intake was assessed every 4 years using a validated questionnaire. Pregnancies were self-reported with case pregnancies lost spontaneously at <20 weeks gestation. Multivariable log-binomial regression models with generalized estimating equations were used to estimate the relative risks (RRs) and 95 % confidence intervals (CIs).

RESULTS

There was a positive linear trend across categories of pre-pregnancy caffeine intake and risk of SAB such that women consuming >400 mg/day had 1.11 (95 % CI 0.98, 1.25) times the risk of SAB compared to women consuming <50 mg/day (p trend = 0.05). Total coffee intake had a positive, linear association with SAB. Compared to women with no pre-pregnancy coffee intake, women consuming ≥4 servings/day had a 20 % (6, 36 %) increased risk of SAB (p trend = 0.01). There was no difference in the association between caffeinated and decaffeinated coffee and risk of SAB. Pre-pregnancy intake of caffeinated tea, caffeinated soda, and decaffeinated soda had no association with SAB.

CONCLUSIONS

Pre-pregnancy coffee consumption at levels ≥4 servings/day is associated with increased risk of SAB, particularly at weeks 8-19.

Signs and symptoms associated with early pregnancy loss: findings from a population-based preconception cohort

STUDY QUESTION

What is the relationship between signs and symptoms of early pregnancy and pregnancy loss <20 weeks' gestation?

SUMMARY ANSWER

Vaginal bleeding is associated with increased incidence of early pregnancy loss, with more severe bleeding and bleeding accompanied by lower abdominal cramping associated with greater incidence of loss; conversely, vomiting is associated with decreased incidence of early pregnancy loss, even in the setting of vaginal bleeding, while nausea alone is not.

WHAT IS KNOWN ALREADY

Two previous cohort studies with preconception enrollment suggested that bleeding is associated with loss while nausea is inversely associated with loss though these studies were limited by small study size and reporting after loss ascertainment. No prior preconception cohort study has examined multiple signs and symptoms in relation to pregnancy loss.

STUDY DESIGN, SIZE, DURATION

Population-based preconception cohort of 501 couples discontinuing contraception to try for pregnancy in 16 counties in Michigan and Texas, USA. Participants were followed daily until positive home pregnancy test or 12 months of trying without an hCG pregnancy; women who became pregnant were followed daily from 2 to 7 weeks post-conception.

PARTICIPANTS, SETTING, METHODS

Three hundred and forty-seven women had a positive home pregnancy test denoting hCG pregnancy. Three hundred and forty-one women remained after excluding ineligible pregnancies. Women recorded daily from 2 to 7 weeks post-conception their signs and symptoms, including vaginal bleeding (none, spotting, light, moderate and heavy), lower abdominal cramping, nausea and vomiting. Pregnancy losses were ascertained by a subsequent negative home pregnancy test, clinical confirmation or onset of menses, depending on gestational age at loss; time-to-loss was measured in days post-conception. Cumulative incidence functions and 95% confidence intervals (CIs) were constructed for each sign or symptom, and hazard ratios (HRs) and 95% CIs for presence compared with absence of signs or symptoms were estimated using Cox proportional hazard models.

MAIN RESULTS AND THE ROLE OF CHANCE

Women experienced lower abdominal cramping (85%), nausea (48%), vomiting (46%) and light/moderate/heavy vaginal bleeding (24%) during early pregnancy. Ninety-five (28%) women experienced a loss. Cumulative incidence of pregnancy loss varied by symptomatology: 19% for vomiting, 27% for lower abdominal cramping, 35% for nausea only, 52% for vaginal bleeding, 81% for vaginal bleeding with lower abdominal cramping. Incidence of pregnancy loss was increased among women with vaginal bleeding (HR: 3.62, 95% CI: 2.29-5.74) and among women with vaginal bleeding and lower abdominal cramping (HR: 5.03, 95% CI: 2.07-12.20). Incidence of pregnancy loss was decreased for women with vomiting (HR: 0.51, 95% CI: 0.30-0.86). In the setting of vaginal bleeding with lower abdominal cramping, vomiting reduced the incidence of pregnancy loss (HR: 0.24, 95% CI: 0.11-0.56).

LIMITATIONS, REASONS FOR CAUTION

There were few losses beyond 14 weeks gestation; thus, the precision of our findings related to losses occurring after the first trimester is limited.

WIDER IMPLICATIONS OF THE FINDINGS

By using sensitive home pregnancy tests, we are able to document and characterize the cumulative incidence of the earliest pregnancy losses, which constitute the majority of losses. The use of daily, prospective capture of signs and symptoms relative to ascertainment of pregnancy loss minimizes potential biases associated with reporting after rather than before a loss, which could potentially distort the relationship between signs and symptoms and pregnancy loss. The findings of our study suggest that it may be useful to develop prognostic models for pregnancy loss based on signs and symptoms.

STUDY FUNDING/COMPETING INTERESTS

This study was supported by the Intramural Research Program of the Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health (contract numbers N01-HD-3-3355; N01-HD-3-3356; N01-HD-3-3358). The authors have no conflict of interest to declare.

Caffeine: Friend or Foe?

The debate on the safety of and regulatory approaches for caffeine continues among various stakeholders and regulatory authorities. This decision-making process comes with significant challenges, particularly when considering the complexities of the available scientific data, making the formulation of clear science-based regulatory guidance more difficult. To allow for discussions of a number of key issues, the North American Branch of the International Life Sciences Institute (ILSI) convened a panel of subject matter experts for a caffeine-focused session entitled "Caffeine: Friend or Foe?," which was held during the 2015 ILSI Annual Meeting. The panelists' expertise covered topics ranging from the natural occurrence of caffeine in plants and interindividual metabolism of caffeine in humans to specific behavioral, reproductive, and cardiovascular effects related to caffeine consumption. Each presentation highlighted the potential risks, benefits, and challenges that inform whether caffeine exposure warrants concern. This paper aims to summarize the key topics discussed during the session.

Maternal caffeine intake during pregnancy and risk of pregnancy loss: a categorical and dose-response meta-analysis of prospective studies

OBJECTIVE

To assess the association between maternal caffeine intake and risk of pregnancy loss using a systematic review and meta-analysis.

DESIGN

Categorical and dose-response meta-analysis of prospective studies.

SETTING

Relevant articles were identified by searching MEDLINE and SCOPUS databases through 30 January 2015. Two authors independently extracted information from eligible studies. Random-effects models were used to derive the summary relative risks (RR) and corresponding 95% CI for specific categories of caffeine consumption and for a continuous association using generalized least-squares trend estimation.

SUBJECTS

A total of 130 456 participants and 3429 cases in fourteen included studies.

RESULTS

Compared with the reference category with no or very low caffeine intake, the RR (95% CI) of pregnancy loss was 1·02 (0·85, 1·24; I(2)=28·3%) for low intake (50-149 mg/d), 1·16 (0·94, 1·41; I 2=49·6%) for moderate intake (150-349 mg/d), 1·40 (1·16, 1·68; I(2)=18·6%) for high intake (350-699 mg/d) and 1·72 (1·40, 2·13; I(2)=0·0%) for very high intake (≥ 700 mg/d). In the dose-response analysis, each 100 mg/d increment in maternal caffeine intake (~1 cup of coffee) was associated with 7% (95% CI 3%, 12%) higher risk of pregnancy loss. Our results may have been affected by publication bias, but the association remained significant for the subset of larger studies. Furthermore, adjustment for smoking and pregnancy symptoms may have been incomplete, potentially resulting in residual confounding.

CONCLUSIONS

Albeit inconclusive, higher maternal caffeine intake was associated with a higher risk of pregnancy loss and adherence to guidelines to avoid high caffeine intake during pregnancy appears prudent.

Prepregnancy Nutrition and Early Pregnancy Outcomes

Implantation failure and pregnancy loss are estimated to affect up to 75% of fertilized ova; however as of yet there is limited empirical evidence, particularly at the population level, for understanding the environmental determinants of these losses. The purpose of this review is to summarize the current knowledge on prepregnancy nutrition and early pregnancy outcomes with particular focus on the outcome of spontaneous abortion among pregnancies conceived naturally and early pregnancy end points among pregnancies conceived through in vitro fertilization. To date, there is limited evidence to support associations of prepregnancy vitamin D and caffeine intake with pregnancy loss. There is suggestive data supporting a link between a healthy diet and lower risk of pregnancy loss. High folate and minimal to no alcohol intake prior to conception have the most consistent evidence supporting an association with lower risk of pregnancy loss.

Effects of restricted caffeine intake by mother on fetal, neonatal and pregnancy outcomes

BACKGROUND

Maternal caffeine consumption during pregnancy may have adverse effects on fetal, neonatal and maternal outcomes.

OBJECTIVES

This review investigates the effects of restricting caffeine intake by mothers on fetal, neonatal and pregnancy outcomes.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (16 January 2015), scanned bibliographies of published studies and corresponded with investigators.

SELECTION CRITERIA

Randomised controlled trials (RCTs) including quasi-RCTs investigating the effect of caffeine and/or supplementary caffeine versus restricted caffeine intake or placebo on pregnancy outcomes.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trials for inclusion and risk of bias, extracted data and checked them for accuracy.

MAIN RESULTS

Two studies met the inclusion criteria but only one contributed data for the prespecified outcomes. Caffeinated instant coffee (568 women) was compared with decaffeinated instant coffee (629 women) and it was found that reducing the caffeine intake of regular coffee drinkers (3+ cups/day) during the second and third trimester by an average of 182 mg/day did not affect birthweight (g) (mean difference (MD) 20.00, 95% confidence interval (CI) -48.68 to 88.68; one study, 1197 participants; low quality evidence), preterm birth (risk ratio (RR) 0.81, 95% CI 0.48 to 1.37; one study, 1153 participants; low quality evidence) or small-for-gestational age (RR 0.97, 95% 0.57 to 1.64; one study, 1150 participants). Risk of bias was moderate in both studies.Two outcomes were assessed and assigned a quality rating using the GRADE methods. Evidence for these two outcomes (birthweight and preterm birth) was assessed as of low quality, with downgrading decisions due to the relatively small sample sizes and the wide confidence interval of the one included trial that contributed data. Neither of the studies reported on any of the other primary outcomes (low birthweight; first trimester fetal loss; perinatal mortality; fetal hypoxia; fetal tachycardia) or on any of the reviews neonatal or maternal outcomes.

AUTHORS' CONCLUSIONS

There is insufficient evidence to confirm or refute the effectiveness of caffeine avoidance on birthweight or other pregnancy outcomes. There is a need to conduct high-quality, double-blinded RCTs to determine whether caffeine has any effect on pregnancy outcome.

A meta-analysis of risk of pregnancy loss and caffeine and coffee consumption during pregnancy

BACKGROUND

Previous reports of the relationship between pregnancy loss and caffeine/coffee consumption have been inconsistent.

OBJECTIVES

To evaluate the association between pregnancy loss and caffeine and coffee consumption.

SEARCH STRATEGY

PubMed was searched for reports published before September 2014, with the keywords "caffeine," "coffee," "beverage," "miscarriage," "spontaneous abortion," and "fetal loss."

SELECTION CRITERIA

Case-control and cohort studies were included when they had been reported in English, the exposure of interest was caffeine/coffee consumption during pregnancy, the outcome of interest was spontaneous abortion or fetal death, and multivariate-adjusted odds ratios (ORs) or risk ratios were provided or could be calculated.

DATA COLLECTION AND ANALYSIS

Data were extracted and combined ORs calculated.

MAIN RESULTS

Overall, 26 studies were included (20 of caffeine and eight of coffee). After adjustment for heterogeneity, caffeine consumption was associated with an increased risk of pregnancy loss (OR 1.32, 95% confidence interval [CI] 1.24-1.40), as was coffee consumption (OR 1.11, 95% CI 1.02-1.21). A dose-response analysis suggested that risk of pregnancy loss rose by 19% for every increase in caffeine intake of 150 mg/day and by 8% for every increase in coffee intake of two cups per day.

CONCLUSIONS

Consumption of caffeine and coffee during pregnancy seems to increase the risk of pregnancy loss.

Caffeine and caffeinated beverage consumption and risk of spontaneous abortion

STUDY QUESTION

Is caffeine and caffeinated beverage consumption associated with the risk of spontaneous abortion (SAB)?

SUMMARY ANSWER

While preconceptional caffeine consumption was not materially associated with an increased risk of SAB, consumption during early pregnancy was associated with a small increased risk of SAB, although the relation was not linear.

WHAT IS KNOWN ALREADY

Caffeine has been hypothesized as a risk factor for SAB since the 1980s; however, results from previous studies have been conflicting.

STUDY DESIGN, SIZE, DURATION

This prospective cohort study included 5132 Danish women planning pregnancy and enrolled from 2007 to 2010.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Participants were women who conceived after entry into the Snart-Gravid cohort and who were aged 18-40, in a stable relationship with a male partner, and did not use fertility treatments to conceive. Women reported their daily caffeine and caffeinated beverage consumption on questionnaires before conception and during early pregnancy. All exposure measurements were prospective with respect to outcome ascertainment. We estimated hazard ratios (HRs) of SAB for categories of caffeine consumption in milligrams (mg) per day and the corresponding 95% confidence intervals (CIs) using Cox proportional hazards regression models with gestational weeks as the time scale.

MAIN RESULTS AND THE ROLE OF CHANCE

There were 732 women (14.3%) who were identified as having a SAB. In the preconceptional period, caffeine consumption was not materially associated with SAB risk (HR comparing ≥300 with <100 mg/day: 1.09; 95% CI: 0.89, 1.33). In early pregnancy, the HRs for 100-199, 200-299 and ≥300 mg/day of caffeine consumption were 1.62 (95% CI: 1.19, 2.22), 1.48 (95% CI: 1.03, 2.13) and 1.23 (95% CI: 0.61, 2.46), respectively, compared with that for <100 mg/day.

LIMITATIONS, REASONS FOR CAUTION

The observed results may be affected by non-differential exposure misclassification, reverse causation and residual confounding.

WIDER IMPLICATIONS OF THE FINDINGS

This is the largest study to date of prospectively measured, preconception caffeine consumption and risk of SAB. We were able to reduce the likelihood of differential left truncation bias and recall bias present in other analyses.

STUDY FUNDING/COMPETING INTERESTS

Snart-Gravid was funded by the NICHD (R21-050264). Dr. Hahn's work was funded in part by the BU Reproductive, Perinatal, and Pediatric Epidemiology Training Grant NIH #T32HD052458. There are no competing interests.

Preconception care: caffeine, smoking, alcohol, drugs and other environmental chemical/radiation exposure

INTRODUCTION

As providing health education, optimizing nutrition, and managing risk factors can be effective for ensuring a healthy outcome for women and her yet un-conceived baby, external influences play a significant role as well. Alcohol, smoking, caffeine use and other similar lifestyle factors, have now become an integral part of the daily life of most men and women, who use/misuse one or more of these harmful substances regularly despite knowledge of their detrimental effects. The adverse health outcomes of these voluntary and involuntary exposures are of even greater concern in women of child bearing age where the exposure has the potential of inflicting harm to two generations. This paper is examining the available literature for the possible effects of caffeine consumption, smoking, alcohol or exposure to chemicals may have on the maternal, newborn and child health (MNCH).

METHODS

A systematic review and meta-analysis of the evidence was conducted to ascertain the possible impact of preconception usage of caffeine, tobacco, alcohol and other illicit drugs; and exposure to environmental chemicals and radiant on MNCH outcomes. A comprehensive strategy was used to search electronic reference libraries, and both observational and clinical controlled trials were included. Cross-referencing and a separate search strategy for each preconception risk and intervention ensured wider study capture.

RESULTS

Heavy maternal preconception caffeine intake of >300 mg/d significantly increase the risk of a subsequent fetal loss by 31% (95% CI: 8-58%). On the other hand, preconception alcohol consumption leads to non-significant 30% increase in spontaneous abortion (RR 1.30; 95% CI: 0.85-1.97). Preconception counselling can lead to a significant decrease in the consumption of alcohol during the first trimester (OR 1.79; 95% CI: 1.08-2.97). Periconception smoking, on the other hand, was found to be associated with an almost 3 times increased risk of congenital heart defects (OR 2.80; 95% CI 1.76-4.47). While the review found limited evidence of preconception environmental exposure on maternal, newborn and child health outcomes, occupational exposure in female radiation workers before conception showed an increased impact in risk of early miscarriages.

CONCLUSION

Identification of substance abuse and environmental history during preconception period provides an opportunity to assist women in reducing major health risks and identify key determinants of healthy pregnancy. Studies have shown that the aversion and prevention of exposure feasibility can play an important role in improving the health of women and their families, however, the results should be interpreted with great caution as there were few studies in each section. Therefore, there is a need for more rigorous studies to test the hypotheses.

Coffee: biochemistry and potential impact on health

This article reviews the diversity of compounds found in coffee beans, the effect of roasting and the potential impact of coffee beverage on health.

Risk of miscarriage among black women and white women in a U.S. Prospective Cohort Study

Many adverse pregnancy outcomes differ by race. We examined the association between self-reported race and miscarriage (pregnancy loss at <20 weeks) in a community-based pregnancy cohort. Women from the southeastern United States (North Carolina, Texas, and Tennessee) were enrolled in "Right from the Start" from 2000 to 2009. They were recruited while trying to conceive or during early pregnancy. Participants completed study ultrasound examinations, interviews, and consent forms for review of medical records. We used proportional hazard models to examine miscarriage risk among black women compared with white women, adjusted for confounders. There were 537 observed miscarriages among 4,070 women, 23% of whom self-identified as black (n = 932). The life table-adjusted cumulative risk of loss after gestational week 5 was 21.3%. With adjustment for age and alcohol use, blacks had increased risk of miscarriage compared with whites (adjusted hazard ratio = 1.57, 95% confidence interval: 1.27, 1.93). When risk of loss before gestational week 10 was dichotomized at the median gestational age, there was little difference, but black women had a greater risk thereafter compared with white women (adjusted hazard ratio = 1.93, 95% confidence interval: 1.48, 2.51). Early pregnancy ultrasound examinations did not differ by race. In summary, self-reported race is independently associated with risk of miscarriage, and the higher risk for black women is concentrated in gestational weeks 10-20.

Effects of restricted caffeine intake by mother on fetal, neonatal and pregnancy outcome

BACKGROUND

Maternal caffeine consumption during pregnancy may have adverse effects on fetal, neonatal and maternal outcomes.

OBJECTIVES

This review investigates the effects of restricting caffeine intake by mothers on fetal, neonatal and pregnancy outcomes.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (31 October 2012), scanned bibliographies of published studies and corresponded with investigators.

SELECTION CRITERIA

Randomised controlled trials (RCTs) including quasi-RCTs investigating the effect of caffeine and/or supplementary caffeine versus restricted caffeine intake or placebo on pregnancy outcomes.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trial quality and extracted data.

MAIN RESULTS

Two studies met the inclusion criteria but only one contributed data for the prespecified outcomes. Caffeinated instant coffee (568 women) was compared with decaffeinated instant coffee (629 women) and it was found that reducing the caffeine intake of regular coffee drinkers (3+ cups/day) during the second and third trimester by an average of 182 mg/day did not affect birthweight or length of gestation.

AUTHORS' CONCLUSIONS

There is insufficient evidence to confirm or refute the effectiveness of caffeine avoidance on birthweight or other pregnancy outcomes. There is a need to conduct high-quality, double-blinded RCTs to determine whether caffeine has any effect on pregnancy outcome.

Maternal caffeine intake during pregnancy is associated with birth weight but not with gestational length: results from a large prospective observational cohort study

BACKGROUND

Pregnant women consume caffeine daily. The aim of this study was to examine the association between maternal caffeine intake from different sources and (a) gestational length, particularly the risk for spontaneous preterm delivery (PTD), and (b) birth weight (BW) and the baby being small for gestational age (SGA).

METHODS

This study is based on the Norwegian Mother and Child Cohort Study conducted by the Norwegian Institute of Public Health. A total of 59,123 women with uncomplicated pregnancies giving birth to a live singleton were identified. Caffeine intake from different sources was self-reported at gestational weeks 17, 22 and 30. Spontaneous PTD was defined as spontaneous onset of delivery between 22+0 and 36+6 weeks (n = 1,451). As there is no consensus, SGA was defined according to ultrasound-based (Marsal, n = 856), population-based (Skjaerven, n = 4,503) and customized (Gardosi, n = 4,733) growth curves.

RESULTS

The main caffeine source was coffee, but tea and chocolate were the main sources in women with low caffeine intake. Median pre-pregnancy caffeine intake was 126 mg/day (IQR 40 to 254), 44 mg/day (13 to 104) at gestational week 17 and 62 mg/day (21 to 130) at gestational week 30. Coffee caffeine, but not caffeine from other sources, was associated with prolonged gestation (8 h/100 mg/day, P <10-7). Neither total nor coffee caffeine was associated with spontaneous PTD risk. Caffeine intake from different sources, measured repeatedly during pregnancy, was associated with lower BW (Marsal-28 g, Skjaerven-25 g, Gardosi-21 g per 100 mg/day additional total caffeine for a baby with expected BW 3,600 g, P <10-25). Caffeine intake of 200 to 300 mg/day increased the odds for SGA (OR Marsal 1.62, Skjaerven 1.44, Gardosi 1.27, P <0.05), compared to 0 to 50 mg/day.

CONCLUSIONS

Coffee, but not caffeine, consumption was associated with marginally increased gestational length but not with spontaneous PTD risk. Caffeine intake was consistently associated with decreased BW and increased odds of SGA. The association was strengthened by concordant results for caffeine sources, time of survey and different SGA definitions. This might have clinical implications as even caffeine consumption below the recommended maximum (200 mg/day in the Nordic countries and USA, 300 mg/day according to the World Health Organization (WHO)) was associated with increased risk for SGA.

Immune system function, stress, exercise and nutrition profile can affect pregnancy outcome: Lessons from a Mediterranean cohort

Pregnancy is associated with major physiological and future psychosocial changes, and maternal adaptation to these changes is crucial for normal foetal development. Psychological stress in pregnancy predicts an earlier birth and lower birth weight. Pregnancy-specific stress contributes directly to preterm delivery. The importance of nutrition and exercise during pregnancy with regard to pregnancy outcome has long been acknowledged. This importance has only been further emphasized by the recent changes in food quality and availability, lifestyle changes and a new understanding of foetal programming’s effects on adult outcomes. We hypothesised that for a successful pregnancy certain events at a nutritional, immune, psycho-emotional and genetic level should be tightly linked. Therefore, in this study we followed an ‘integrative’ approach to investigate how maternal stress, nutrition, pregnancy planning and exercise influence pregnancy outcome. A key finding of our study is that there was a significant reduction in the intake of alcohol, caffeine-containing and sugary drinks during pregnancy. However, passive smoking in the household remained unchanged. In terms of immune profile, a significant inverse correlation was noted between difficulty to ‘fight’ an infection and number of colds (r=−0.289, P=0.003) as well as the number of infections (r=−0.446, P<0.0001) during pregnancy. The vast majority of the pregnant women acquired a more sedentary lifestyle in the third trimester. In planned, but not in unplanned, pregnancies stress predicted infant weight, independent of age and body mass index (BMI). Notably, in mothers with negative attitudes towards the pregnancy, those with an unplanned pregnancy gave birth to infants with significantly higher weights than those with planned pregnancies. Collectively these data suggest that there is a higher order of complexity, possibly involving gene-environment interactions that work together to ensure a positive outcome for the mother as well as the foetus.

Spontaneous abortion and a diet drug containing caffeine and ephedrine: a study within the Danish national birth cohort

Background

Medications may be consumed periconceptionally before a woman knows she is pregnant. In this study, the authors evaluate the association of a prescription diet drug (Letigen) containing ephedrine (20 mg) and caffeine (200 mg) with spontaneous abortion (SAB) in the Danish National Birth Cohort.

Methods

Women were recruited during their first prenatal visit from 1996–2002. Pre-conception and early pregnancy medication use was reported on the enrollment form, and pregnancy outcome was determined by linking the mother's Civil Registration Number to the Medical Birth Registry and the National Hospital Discharge Register. Of 97,903 eligible pregnancies, 4,443 ended in SAB between 5 and 20 completed gestational weeks, inclusive. Letigen use was reported for 565 pregnancies. Cox regression models accounting for left truncation were fit to estimate the effect of pre-conception and early pregnancy Letigen use on SAB.

Principal Findings

The estimated maternal age-adjusted hazard ratio for SAB was 1.1 (95% confidence interval 0.8–1.6) for any periconceptional Letigen use compared to no periconceptional use.

Conclusions

Although Letigen has high levels of caffeine (the recommended 3 pills/day are approximately equivalent to caffeine from 6 cups of coffee), periconceptional use does not appear to be associated with an appreciably increased hazard of clinically recognized SAB.

Evaluation of the reproductive and developmental risks of caffeine

A risk analysis of in utero caffeine exposure is presented utilizing epidemiological studies and animal studies dealing with congenital malformation, pregnancy loss, and weight reduction. These effects are of interest to teratologists, because animal studies are useful in their evaluation. Many of the epidemiology studies did not evaluate the impact of the "pregnancy signal," which identifies healthy pregnancies and permits investigators to identify subjects with low pregnancy risks. The spontaneous abortion epidemiology studies were inconsistent and the majority did not consider the confounding introduced by not considering the pregnancy signal. The animal studies do not support the concept that caffeine is an abortafacient for the wide range of human caffeine exposures. Almost all the congenital malformation epidemiology studies were negative. Animal pharmacokinetic studies indicate that the teratogenic plasma level of caffeine has to reach or exceed 60 µg/ml, which is not attainable from ingesting large amounts of caffeine in foods and beverages. No epidemiological study described the "caffeine teratogenic syndrome." Six of the 17 recent epidemiology studies dealing with the risk of caffeine and fetal weight reduction were negative. Seven of the positive studies had growth reductions that were clinically insignificant and none of the studies cited the animal literature. Analysis of caffeine's reproductive toxicity considers reproducibility and plausibility of clinical, epidemiological, and animal data. Moderate or even high amounts of beverages and foods containing caffeine do not increase the risks of congenital malformations, miscarriage or growth retardation. Pharmacokinetic studies markedly improve the ability to perform the risk analyses.

Methylxanthines during pregnancy and early postnatal life

World-wide, many fetuses and infants are exposed to methylxanthines via maternal consumption of coffee and other beverages containing these substances. Methylxanthines (caffeine, theophylline and aminophylline) are also commonly used as a medication for apnea of prematurity.The metabolism of methylxanthines is impaired in pregnant women, fetuses and neonates, leading to accumulating levels thereof. Methylxanthines readily passes the placenta barrier and enters all tissues and thus may affect the fetus/newborn at any time during pregnancy or postnatal life, given that the effector systems are mature.At clinically relevant doses, the major effector system for methylxanthines is adenosine receptors. Animal studies suggest that adenosine receptors in the cardiovascular, respiratory and immune system are developed at birth, but that cerebral adenosine receptors are not fully functional. Furthermore animal studies have shown protective positive effects of methylxanthines in situations of hypoxia/ischemia in neonates. Similarly, a positive long-term effect on lung function and CNS development was found in human preterm infants treated with high doses of caffeine for apneas. There is now evidence that the overall benefits from methylxanthine therapy for apnea of prematurity outweigh potential short-term risks.On the other hand it is important to note that experimental studies have indicated that long-term effects of caffeine during pregnancy and postnatally may include altered behavior and altered respiratory control in the offspring, although there is currently no human data to support this.Some epidemiology studies have reported negative effects on pregnancy and perinatal outcomes related to maternal ingestion of high doses of caffeine, but the results are inconclusive. The evidence base for adverse effects of caffeine in first third of pregnancy are stronger than for later parts of pregnancy and there is currently insufficient evidence to advise women to restrict caffeine intake after the first trimester.

Maternal sleep deprivation, sedentary lifestyle and cooking smoke: Risk factors for miscarriage: A case control study

AIMS

To determine risk factors for miscarriage.

METHODS

A case control study was carried out at the gynaecological wards and antenatal clinics of the De Soysa Maternity Hospital in Sri Lanka. A case was defined as that of mothers with a confirmed diagnosis of partial or full expulsion of the fetus during the first 28 weeks of gestation. Controls comprised ante-natal clinic attendees whose period of gestation was <28 weeks and carrying a viable fetus. Two hundred and thirty cases and 504 controls were selected. A pre-tested interviewer-administered questionnaire and modified life events inventory were used to gather data. Multivariate logistic regression was applied separately for first and second trimester miscarriages and the results were expressed as odds ratios (OR) and as 95% confidence intervals (95% CI).

RESULTS

Sleeping < or =8 h/day (OR:3.80, 95% CI:1.01-14.3) was found to be a risk factor for first trimester miscarriage controlling for the effect of period of gestation. Sleeping < or =8 h/day (OR:2.04, 95% CI:1.24-3.37), standing < or =3 h/day (OR:1.83, 95% CI:1.08-3.10), exposure to cooking smoke (OR:3.83, 95% CI:1.50-9.90) and physical trauma during the pregnancy (OR:43.2, 95% CI:4.55-411.4) were found to be risk factors for second trimester miscarriage controlling for the effect of period of gestation.

CONCLUSIONS

Sleep deprivation, a sedentary lifestyle, exposure to cooking smoke and physical trauma during pregnancy were risk factors for miscarriage. Most of the risk factors are therefore modifiable.

Severity and duration of nausea and vomiting symptoms in pregnancy and spontaneous abortion

BACKGROUND

Earlier studies have shown an inverse association between the presence of nausea and vomiting in pregnancy (NVP) and spontaneous abortion (SAB), but no study to date has examined the effects of symptom duration on the risk of SAB.

METHODS

We examined NVP symptom severity and duration in relation to the occurrence of SAB. Data were collected from 2407 pregnant women in three US cities between 2000 and 2004 through interviews, ultrasound assessments and medical records abstractions. Discrete-time continuation ratio logistic survival models were used to examine the association between NVP and pregnancy loss.

RESULTS

Lack of NVP symptoms was associated with increased risk for SAB [adjusted odds ratio (OR) = 3.2, 95% confidence interval (CI): (2.4, 4.3)], compared with having any symptoms. Reduced risks for SAB were found across most maternal age groups for those with NVP for at least half of their pregnancy, but the effects were much stronger in the oldest maternal age group [OR = 0.2, 95% CI: (0.1, 0.8)].

CONCLUSIONS

The absence of NVP symptoms is associated with an increased risk of early pregnancy loss. As symptom duration decreases, the likelihood of early loss increases, especially among women in the oldest maternal age group.

A review of the epidemiologic evidence concerning the reproductive health effects of caffeine consumption: a 2000-2009 update

This review of human studies of caffeine and reproductive health published between January 2000 and December 2009 serves to update the comprehensive review published by Leviton and Cowan (2002). The adverse reproductive outcomes addressed in this review include: (1) measures of subfecundity; (2) spontaneous abortion; (3) fetal death; (4) preterm birth; (5) congenital malformations; and (6) fetal growth restriction. Methodologic challenges and considerations relevant to investigations of each reproductive endpoint are summarized, followed by a brief critical review of each study. The evidence for an effect of caffeine on reproductive health and fetal development is limited by the inability to rule out plausible alternative explanations for the observed associations, namely confounding by pregnancy symptoms and smoking, and by exposure measurement error. Because of these limitations, the weight of evidence does not support a positive relationship between caffeine consumption and adverse reproductive or perinatal outcomes.

Caffeine levels in beverages from Argentina's market: application to caffeine dietary intake assessment

The caffeine content of different beverages from Argentina's market was measured. Several brands of coffees, teas, mates, chocolate milks, soft and energy drinks were analysed by high-performance liquid chromatography (HPLC) with ultraviolet detection. The highest concentration level was found in short coffee (1.38 mg ml(-1)) and the highest amount per serving was found in instant coffee (95 mg per serving). A consumption study was also carried out among 471 people from 2 to 93 years of age to evaluate caffeine total dietary intake by age and to identify the sources of caffeine intake. The mean caffeine intake among adults was 288 mg day(-1) and mate was the main contributor to that intake. The mean caffeine intake among children of 10 years of age and under was 35 mg day(-1) and soft drinks were the major contributors to that intake. Children between 11 and 15 years old and teenagers (between 16 and 20 years) had caffeine mean intakes of 120 and 240 mg day(-1), respectively, and mate was the major contributor to those intakes. Drinking mate is a deep-rooted habit among Argentine people and it might be the reason for their elevated caffeine mean daily intake.

Caffeine intake during pregnancy, late miscarriage and stillbirth

Caffeine is a commonly consumed drug during pregnancy with the potential to affect the developing fetus. Findings from previous studies have shown inconsistent results. We recruited a cohort of 2,643 pregnant women, aged 18-45 years, attending two UK maternity units between 8 and 12 weeks gestation from September 2003 to June 2006. We used a validated tool to assess caffeine intake at different stages of pregnancy and related this to late miscarriage and stillbirth, adjusting for confounders, including salivary cotinine as a biomarker of smoking status. There was a strong association between caffeine intake in the first trimester and subsequent late miscarriage and stillbirth, adjusting for confounders. Women whose pregnancies resulted in late miscarriage or stillbirth had higher caffeine intakes (geometric mean = 145 mg/day; 95% CI: 85-249) than those with live births (103 mg/day; 95% CI: 98-108). Compared to those consuming < 100 mg/day, odds ratios increased to 2.2 (95% CI: 0.7-7.1) for 100-199 mg/day, 1.7 (0.4-7.1) for 200-299 mg/day, and 5.1 (1.6-16.4) for 300+ mg/day (P (trend) = 0.004). Greater caffeine intake is associated with increases in late miscarriage and stillbirth. Despite remaining uncertainty in the strength of association, our study strengthens the observational evidence base on which current guidance is founded.

Consequences of smoking and caffeine consumption during pregnancy in women with type 1 diabetes

OBJECTIVE

To test the hypothesis that, in women with type 1 diabetes, prenatal smoking and caffeine consumption during pregnancy are associated with an increased risk of adverse maternal and perinatal outcomes.

METHODS

A secondary analysis of data on pregnant women with type 1 diabetes from an interdisciplinary program of Diabetes in Pregnancy. Women were interviewed monthly, by a trained non-medical member of the research team, using a standardized questionnaire, to ascertain daily smoking habits and caffeine consumption.

RESULTS

Smoking and caffeine information were available on 191 pregnancies, 168 progressing beyond 20 weeks of gestation. Early pregnancy smoking (OR 3.3, 95% CI 1.2, 8.7) and caffeine consumption (OR 4.5, 95% CI 1.2, 16.8) were associated with increased risk of spontaneous abortion when controlling for age, years since diagnosis of diabetes, previous spontaneous abortion, nephropathy and retinopathy. Smoking throughout pregnancy was significantly associated with decreased birth weight and prolonged neonatal hospital stay. Smoking throughout pregnancy (OR 0.2, 95% 0.1, 1.0) and caffeine consumption after 20 weeks (OR 0.3, 95% CI 0.1, 1.0) were associated with reduced risk of pre-eclampsia.

CONCLUSIONS

Caffeine consumption during early pregnancy, regardless of glycemic control, increases the risk of spontaneous abortion. Smoking throughout pregnancy and caffeine consumption are associated with reduced risk of pre-eclampsia.

Effects of restricted caffeine intake by mother on fetal, neonatal and pregnancy outcome

BACKGROUND

Maternal caffeine consumption during pregnancy may have adverse effects on fetal, neonatal and maternal outcomes.

OBJECTIVES

This review investigates the effects of restricting caffeine intake by mothers on fetal, neonatal and pregnancy outcomes.

SEARCH STRATEGY

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (December 2008), scanned bibliographies of published studies and corresponded with investigators.

SELECTION CRITERIA

Randomised controlled trials including quasi-randomised controlled trials (RCTs) investigating the effect of caffeine and/or supplementary caffeine versus restricted caffeine intake or placebo on pregnancy outcome.

DATA COLLECTION AND ANALYSIS

The two review authors independently assessed trial quality and extracted data.

MAIN RESULTS

One study met the inclusion criteria. Caffeinated instant coffee (568 women) was compared with decaffeinated instant coffee (629 women) and it was found that reducing the caffeine intake of regular coffee drinkers (3+ cups/day) during the second and third trimester by an average of 182 mg/day did not affect birthweight or length of gestation.

AUTHORS' CONCLUSIONS

There is insufficient evidence to confirm or refute the effectiveness of caffeine avoidance on birthweight or other pregnancy outcomes. There is a need to conduct high-quality, double-blinded RCTs to determine whether caffeine has any effect on pregnancy outcome.

Maternal caffeine consumption during pregnancy and the risk of miscarriage: a prospective cohort study

OBJECTIVE

The objective of the study was to examine whether the risk of miscarriage is associated with caffeine consumption during pregnancy after controlling for pregnancy-related symptoms.

STUDY DESIGN

This was a population-based prospective cohort study.

RESULTS

An increasing dose of daily caffeine intake during pregnancy was associated with an increased risk of miscarriage, compared with no caffeine intake, with an adjusted hazard ratio (aHR) of 1.42 (95% confidence interval 0.93 to 2.15) for caffeine intake of less than 200 mg/day, and aHR of 2.23 (1.34 to 3.69) for intake of 200 or more mg/day, respectively. Nausea or vomiting during pregnancy did not materially affect this observed association, nor did the change in intake pattern of caffeine during pregnancy. In addition, the magnitude of the association appeared to be stronger among women without a history of miscarriage (aHR 2.33, 1.48 to 3.67) than that among women with such a history (aHR 0.81, 0.34 to 1.94).

CONCLUSION

Our results demonstrated that high doses of caffeine intake during pregnancy increase the risk of miscarriage, independent of pregnancy-related symptoms.

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

OBJECTIVE

The aim of this study was to examine the association between biological, behavioural and lifestyle risk factors and risk of miscarriage.

DESIGN

Population-based case-control study.

SETTING

Case-control study nested within a population-based, two-stage postal survey of reproductive histories of women randomly sampled from the UK electoral register.

POPULATION

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).

METHODS

Women were questioned about socio-demographic, behavioural and other factors in their most recent pregnancy.

MAIN OUTCOME MEASURE

First trimester miscarriage.

RESULTS

After adjustment for confounding, the following were independently associated with increased risk: high maternal age; previous miscarriage, termination and infertility; assisted conception; low pre-pregnancy body mass index; regular or high alcohol consumption; feeling stressed (including trend with number of stressful or traumatic events); high paternal age and changing partner. Previous live birth, nausea, vitamin supplementation and eating fresh fruits and vegetables daily were associated with reduced risk, as were feeling well enough to fly or to have sex. After adjustment for nausea, we did not confirm an association with caffeine consumption, smoking or moderate or occasional alcohol consumption; nor did we find an association with educational level, socio-economic circumstances or working during pregnancy.

CONCLUSIONS

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.

Exposure-measurement error is frequently ignored when interpreting epidemiologic study results

INTRODUCTION

One important source of error in study results is error in measuring exposures. When interpreting study results, one should consider the impact that exposure-measurement error (EME) might have had on study results.

METHODS

To assess how often this consideration is made and the form it takes, journal articles were randomly sampled from original articles appearing in the American Journal of Epidemiology and Epidemiology in 2001, and the International Journal of Epidemiology between December 2000 and October 2001.

RESULTS

Twenty-two (39%) of the 57 articles surveyed mentioned nothing about EME. Of the 35 articles that mentioned something about EME, 16 articles described qualitatively the effect EME could have had on study results. Only one study quantified the impact of EME on study results; the investigators used a sensitivity analysis. Few authors discussed the measurement error in their study in any detail.

CONCLUSIONS

Overall, the potential impact of EME on error in epidemiologic study results appears to be ignored frequently in practice.

Coffee and health: a review of recent human research

Coffee is a complex mixture of chemicals that provides significant amounts of chlorogenic acid and caffeine. Unfiltered coffee is a significant source of cafestol and kahweol, which are diterpenes that have been implicated in the cholesterol-raising effects of coffee. The results of epidemiological research suggest that coffee consumption may help prevent several chronic diseases, including type 2 diabetes mellitus, Parkinson's disease and liver disease (cirrhosis and hepatocellular carcinoma). Most prospective cohort studies have not found coffee consumption to be associated with significantly increased cardiovascular disease risk. However, coffee consumption is associated with increases in several cardiovascular disease risk factors, including blood pressure and plasma homocysteine. At present, there is little evidence that coffee consumption increases the risk of cancer. For adults consuming moderate amounts of coffee (3-4 cups/d providing 300-400 mg/d of caffeine), there is little evidence of health risks and some evidence of health benefits. However, some groups, including people with hypertension, children, adolescents, and the elderly, may be more vulnerable to the adverse effects of caffeine. In addition, currently available evidence suggests that it may be prudent for pregnant women to limit coffee consumption to 3 cups/d providing no more than 300 mg/d of caffeine to exclude any increased probability of spontaneous abortion or impaired fetal growth.

Stillbirth and slow metabolizers of caffeine: comparison by genotypes

BACKGROUND

Cytochrome P4501A2 (CYP1A2) and N-acetyltransferase 2 (NAT2) are key enzymes in the metabolism of caffeine. The polymorphism of these genes facilitates the detection of fast and slow metabolizers, and if caffeine is causally related to stillbirth, we expect slow metabolizers to have a higher risk of stillbirth at any given intake of caffeine. Gluthatione S-transferase alpha1 (GSTA1) may also be active in the metabolism of caffeine as it conjugates glutathione to aromatic amines. Our study, therefore, included analyses of the association between GSTA1 and stillbirth.

METHODS

A nested case non-case study among women who participated in the Danish National Birth Cohort: 142 cases of singleton stillbirths and 157 controls of singleton live births.

RESULTS

Slow oxidizer status (CYP1A2), slow acetylator status (NAT2), and low activity of GSTA1 were not individually associated with the risk of stillbirth [odds ratio (OR) = 1.06, 95% confidence interval (95% CI) 0.67-1.67, OR = 0.95, 95% CI 0.60-1.51, and OR = 1.42, 95% CI 0.88-2.28, respectively]. We did, however, observe that subjects with a combination of slow CYP1A2, slow NAT2, and low GSTA1 genes had almost a 2-fold risk of stillbirth compared with subjects with other combinations of genotypes.

CONCLUSIONS

We found no link between any single genotype and the risk of stillbirth. An association between a combination of genotypes and stillbirth was discovered. Caffeine may be causally related to stillbirth, but larger studies using Mendelian randomization are needed to verify this.

Modifiable risk factors for impaired fertility in women: What nurse practitioners need to know

PURPOSE

To provide an overview of impaired fertility in childbearing-aged women, to review the current research on modifiable lifestyle risk factors implicated in its development, and to suggest strategies for nurse practitioners (NPs) to assist women in behavioral changes that will allow them to protect their fertility.

DATA SOURCES

Original research articles and comprehensive review articles identified through Medline, CINAHL, and OVID databases.

CONCLUSIONS

Research has shown that advancing age, a history of a sexually transmitted infection and/or pelvic inflammatory disease, extremes of body weight, and tobacco and caffeine use are potentially modifiable risk factors in the development of impaired fertility.

IMPLICATIONS FOR PRACTICE

NPs must be aware of the link between these behaviors and the development of impaired fertility in order to assist women in preserving their fertility. Individual counseling, education, and community-wide education strategies are discussed.

Coffee and fetal death: a cohort study with prospective data

The authors conducted a cohort study within the Danish National Birth Cohort to determine whether coffee consumption during pregnancy is associated with late fetal death (spontaneous abortion and stillbirth). A total of 88,482 pregnant women recruited from March 1996 to November 2002 participated in a comprehensive interview on coffee consumption and potentially confounding factors in pregnancy. Information on pregnancy outcome was obtained from the National Hospital Discharge Register and medical records. The authors detected 1,102 fetal deaths. High levels of coffee consumption were associated with an increased risk of fetal death. Relative to nonconsumers of coffee, the adjusted hazard ratios for fetal death associated with coffee consumption of 1/2-3, 4-7, and > or =8 cups of coffee per day were 1.03 (95% confidence interval (CI): 0.89, 1.19), 1.33 (95% CI: 1.08, 1.63), and 1.59 (95% CI: 1.19, 2.13), respectively. Reverse causation due to unrecognized fetal demise may explain the association between coffee intake and risk of fetal death prior to 20 completed weeks' gestation but not the association with fetal loss following 20 completed weeks' gestation. Consumption of coffee during pregnancy was associated with a higher risk of fetal death, especially losses occurring after 20 completed weeks of gestation.

Maternal Caffeine Consumption and Spontaneous Abortion

Since the 1980s, numerous studies have investigated whether caffeine intake during pregnancy affects the risk of spontaneous abortion. A clear consensus, however, has not been reached. Because of the public health importance of this question, we reviewed the results of 15 epidemiologic studies on this topic, with particular attention to the specific methodologic problems that would generate biased findings. These include selection and recall bias, confounding, several issues pertaining to exposure measurement, and the failure to account for fetal karyotype, caffeine metabolism, the timing of fetal demise, and the possibility that an effect of caffeine may be gestational age-specific. All of the studies reviewed suffer from important methodologic limitations that hinder both the interpretation of each study individually and the comparison of results across studies. Despite the fact that most epidemiologic studies have observed a positive association between maternal caffeine intake and the risk of spontaneous abortion, we conclude that the evidence must be considered to be equivocal, given the biases likely present and the fact that most of the potential biases would tend to overestimate any association. Until studies can overcome these limitations, evidence for a causal link between caffeine and spontaneous abortion will remain inconclusive.

The effect of caffeine consumption and nausea on the risk of miscarriage

Evidence for a harmful effect of caffeine intake on risk of miscarriage (spontaneous abortion) is inconsistent and nausea during pregnancy has been claimed to explain any association seen. The objective of this analysis was to determine whether caffeine consumption both before and during pregnancy influenced the risk of miscarriage in a group of pregnant women in the UK. We examined the association with maternal caffeine intake in a case-control study of 474 nulliparous women. Participants were recruited during the years 1987-89 from the Royal Berkshire Hospital in Reading and from a large group practice situated within the hospital's catchment area. Cases were 160 women with a clinically diagnosed miscarriage and controls were 314 pregnant women attending for antenatal care. Information on coffee/tea/cola consumption and potential confounders was collected by interview and caffeine content was assigned to individual drinks according to published data on caffeine content of beverages. Compared with a maternal caffeine intake of < 151 mg/day, we found evidence that caffeine consumption > 300 mg/day doubled the risk of miscarriage. Adjusted odds ratios were 1.94 [95% CI 1.04, 3.63] for 301-500 mg/day and 2.18 [95% CI 1.08, 4.40] for > 500 mg/day. This effect could not be explained by nausea in pregnancy. Nausea appeared to be strongly independently associated with a reduced risk of miscarriage (test for trend P < 0.0001). There was no evidence that prepregnancy caffeine consumption affected the risk. Our results indicate that high caffeine consumption during pregnancy (>300 mg/day), in particular coffee consumption, is an independent risk factor for increased risk and nausea is an independent protective factor for a lower risk of miscarriage.

Effects of caffeine on human health

Caffeine is probably the most frequently ingested pharmacologically active substance in the world. It is found in common beverages (coffee, tea, soft drinks), in products containing cocoa or chocolate, and in medications. Because of its wide consumption at different levels by most segments of the population, the public and the scientific community have expressed interest in the potential for caffeine to produce adverse effects on human health. The possibility that caffeine ingestion adversely affects human health was investigated based on reviews of (primarily) published human studies obtained through a comprehensive literature search. Based on the data reviewed, it is concluded that for the healthy adult population, moderate daily caffeine intake at a dose level up to 400 mg day(-1) (equivalent to 6 mg kg(-1) body weight day(-1) in a 65-kg person) is not associated with adverse effects such as general toxicity, cardiovascular effects, effects on bone status and calcium balance (with consumption of adequate calcium), changes in adult behaviour, increased incidence of cancer and effects on male fertility. The data also show that reproductive-aged women and children are 'at risk' subgroups who may require specific advice on moderating their caffeine intake. Based on available evidence, it is suggested that reproductive-aged women should consume </=300 mg caffeine per day (equivalent to 4.6 mg kg(-1) bw day(-1) for a 65-kg person) while children should consume </=2.5 mg kg(-1) bw day(-1).

Interactions of caffeine and restraint stress during pregnancy in mice

The maternal and developmental toxicity of combined exposure to restraint stress and caffeine was assessed in mice. On gestational Days 0-18, three groups of plug-positive females (n = 13-15) were given by gavage caffeine at 30, 60, and 120 mg/kg/day. Three additional groups received the same caffeine doses and were restrained for 2 hr/day. Control groups included restrained and unrestrained plug-positive mice not exposed to caffeine. All animals in the group concurrently exposed to 120 mg/kg/day of caffeine and restraint died during the experimental period. In the remaining groups, cesarean sections were performed on Day 18 of gestation, and the fetuses were weighed and examined for external, internal, and skeletal malformations and variations. Although maternal and embryo/fetal toxicity were observed at all caffeine doses, the adverse maternal and developmental effects were significantly enhanced in the groups concurrently exposed to caffeine and restraint. It was especially remarkable at 60 and 120 mg/kg/day. The results of this study suggest that maternal and developmental toxic effects might occur if high amounts of caffeine were consumed by women under a notable stress during pregnancy.