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

Maternal caffeine intake during pregnancy and the risk of delivering a small for gestational age baby: Kuopio Birth Cohort

PURPOSE

High caffeine intake during pregnancy is associated with restricted fetal growth. We aimed to evaluate the association between maternal caffeine intake during early and late pregnancy and the risk of delivering a small for gestational age (SGA) baby.

METHODS

Kuopio Birth Cohort (KuBiCo) is a prospective cohort study including women whose pregnancies and deliveries were treated at the prenatal clinics in outpatient healthcare centers and in Kuopio University Hospital, Finland. Maternal diet and caffeine intake during the first (n = 2007) and third (n = 4362) trimester of pregnancy were assessed using a 160-item food frequency questionnaire (2013-2022). SGA was defined as birth weight corrected for gestational age below  - 2 standard deviations from the mean, according to the sex-specific Finnish fetal growth curves.

RESULTS

Altogether in 32 and 38% (1st and 3rd trimester) of all women and in 44 and 52% of coffee drinkers, caffeine intake exceeded the recommendation for caffeine intake ( ≤ 200 mg/day) during pregnancy. The women with moderate (51-200 mg/day) (aOR 1.87; 95% CI: 1.16-3.02) and high (> 200 mg/day) (aOR 1.51; 95% CI: 1.08-2.10) caffeine intake during the first trimester were in the highest risk of having an SGA newborn. Caffeine intake in the third trimester of pregnancy was not associated with SGA.

CONCLUSIONS

Moderate and high caffeine intake during early pregnancy is associated with SGA. As the results suggest that even moderate caffeine intake during the first trimester may increase the risk of SGA, the intake within recommendation limits does not necessarily appear to be safe for pregnant women and their newborns.

Maternal caffeine, coffee and cola drink intake and the risk of gestational diabetes - Kuopio Birth Cohort

AIMS

Coffee intake is associated with a decreased risk of type 2 diabetes among non-pregnant people. We aimed to investigate the association between caffeine, coffee and cola drink intake in early pregnancy and the risk of gestational diabetes (GDM).

METHODS

Kuopio Birth Cohort (KuBiCo) is a prospective cohort study including pregnant women who were followed at the prenatal clinics in outpatient healthcare centers and gave birth in Kuopio University Hospital, Finland (n=2214). Maternal diet during the first trimester of pregnancy was assessed using a 160-item food frequency questionnaire. GDM was diagnosed by oral glucose tolerance test according to the Finnish national guidelines mainly between 24 and 28 gestational weeks.

RESULTS

Women with moderate coffee intake in the first trimester were less likely diagnosed with GDM than women without coffee intake in an age-adjusted model (OR 0.87; 95% CI 0.76-0.99; p = 0.03), but the association was attenuated in multi-adjusted models (p = 0.11). No association was found between caffeine intake and GDM. One third (32.4%) of pregnant women consumed caffeine over the recommendation (> 200 mg/d). Women who consumed cola drinks more than the median (33.3 mL/d) had an increased risk of GDM (OR 1.29; 95% CI 1.02-1.63, p = 0.037) in multi-adjusted model compared to those who consumed less.

CONCLUSIONS

Caffeine intake during the first trimester of pregnancy was not associated with the risk of GDM but a minor non-significant decrease was seen with moderate coffee intake. Although the average consumption of cola drinks was low in the KuBiCo cohort, higher consumption was associated with an increased risk of GDM. Further studies are needed to evaluate the safe amount of coffee during pregnancy, since the recommended caffeine intake was exceeded in almost half of the coffee drinkers.

P-gp expression inhibition mediates placental glucocorticoid barrier opening and fetal weight loss

BACKGROUND

Prenatal adverse environments can cause fetal intrauterine growth retardation (IUGR) and higher susceptibility to multiple diseases after birth, related to multi-organ development programming changes mediated by intrauterine overexposure to maternal glucocorticoids. As a glucocorticoid barrier, P-glycoprotein (P-gp) is highly expressed in placental syncytiotrophoblasts; however, the effect of P-gp on the occurrence of IUGR remains unclear.

METHODS

Human placenta and fetal cord blood samples of IUGR fetuses were collected, and the related indexes were detected. Pregnant Wistar rats were administered with 30 mg/kg·d (low dose) and 120 mg/kg·d (high dose) caffeine from gestational day (GD) 9 to 20 to construct the rat IUGR model. Pregnant mice were administered with caffeine (120 mg/kg·d) separately or combined with sodium ferulate (50 mg/kg·d) from gestational day GD 9 to 18 to confirm the intervention target on fetal weight loss caused by prenatal caffeine exposure (PCE). The fetal serum/placental corticosterone level, placental P-gp expression, and related indicator changes were analyzed. In vitro, primary human trophoblasts and BeWo cells were used to confirm the effect of caffeine on P-gp and its mechanism.

RESULTS

The placental P-gp expression was significantly reduced, but the umbilical cord blood cortisol level was increased in clinical samples of the IUGR neonates, which were positively and negatively correlated with the neonatal birth weight, respectively. Meanwhile, in the PCE-induced IUGR rat model, the placental P-gp expression of IUGR rats was decreased while the corticosterone levels of the placentas/fetal blood were increased, which were positively and negatively correlated with the decreased placental/fetal weights, respectively. Combined with the PCE-induced IUGR rat model, in vitro caffeine-treated placental trophoblasts, we confirmed that caffeine decreased the histone acetylation and expression of P-gp via RYR/JNK/YB-1/P300 pathway, which inhibited placental and fetal development. We further demonstrated that P-gp inducer sodium ferulate could reverse the inhibitory effect of caffeine on the fetal body/placental weight. Finally, clinical specimens and other animal models of IUGR also confirmed that the JNK/YB-1 pathway is a co-regulatory mechanism of P-gp expression inhibition, among which the expression of YB-1 is the most stable. Therefore, we proposed that YB-1 could be used as the potential early warning target for the opening of the placental glucocorticoid barrier, the occurrence of IUGR, and the susceptibility of a variety of diseases.

CONCLUSIONS

This study, for the first time, clarified the critical role and epigenetic regulation mechanism of P-gp in mediating the opening mechanism of the placental glucocorticoid barrier, providing a novel idea for exploring the early warning, prevention, and treatment strategies of IUGR.

Coffee intake and trace element blood concentrations in association with renal cell cancer among smokers

PURPOSE

To determine whether higher coffee intake may reduce the risk of renal cell cancer (RCC) associated with lead (Pb) and other heavy metals with known renal toxicity.

METHODS

We conducted a nested case-control study of male smokers (136 RCC cases and 304 controls) within the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study. Cases diagnosed with RCC at 5 or more years following cohort enrollment were matched to controls on age (± 7 years) and whole blood draw date (± 30 days). Conditional logistic regression (using two-sided tests) was used to test for main effects and additive models of effect modification.

RESULTS

After a mean follow-up of 16.3 years, coffee consumption was not significantly associated with renal cell cancer risk, when adjusting for blood concentrations of Cd, Hg, and Pb and RCC risk factors (age, smoking, BMI, and systolic blood pressure) (p-trend, 0.134). The association with above median blood Pb and RCC (HR = 1.69, 95% CI 1.06, 2.85) appeared to be modified by coffee consumption, such that RCC risk among individuals with both increased coffee intake and higher blood lead concentration were more than threefold higher RCC risk (HR = 3.40, 95% CI 1.62, 7.13; p-trend, 0.003).

CONCLUSION

Contrary to our initial hypothesis, this study suggests that heavy coffee consumption may increase the previously identified association between higher circulating lead (Pb) concentrations and increased RCC risk. Improved assessment of exposure, including potential trace element contaminants in coffee, is needed.

Caffeine use during pregnancy: prevalence of use and newborn consequences in a cohort of French pregnant women

Many pregnant women, in the world, drink caffeine-containing beverages. Maternal caffeine consumption during pregnancy may have adverse effects on foetus but results are conflicting. Our goals were to estimate the prevalence of caffeine use in a cohort of French pregnant women using maternal self-reports and to evaluate the association between caffeine consumption during pregnancy and delivery and newborn characteristics. All pregnant women who gave birth in a large French urban area during a limited period of time were included (in total 724 mothers were included). Coffee, tea or cola consumption as well as pregnancy and neonate characteristics were analysed. The mean consumption of caffeine per day slightly decreased from the first to the third trimester of pregnancy: 587 caffeine users, with a consumption of caffeine of 59.2 ± 61.5 mg/day during the first trimester as compared to 577 consumers (54.3 ± 55.4 mg/day) during the third trimester, respectively. A significant decrease of neonates' birth length was observed when mothers were using at least 100 mg/day (or two cups) of caffeine during the second and third trimesters but this difference was no longer significant after adjustment on potential confounding factors such as tobacco use. The potential existence of other confounders (e.g. poorer dietary habits or other lifestyle variables) that might also be associated with reduced birth length, may not be excluded. Caffeine use during pregnancy was associated with reduced birth length but this effect was no longer significant after adjustment on potential confounding variables.

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.

Miscarriage matters: the epidemiological, physical, psychological, and economic costs of early pregnancy loss

Miscarriage is generally defined as the loss of a pregnancy before viability. An estimated 23 million miscarriages occur every year worldwide, translating to 44 pregnancy losses each minute. The pooled risk of miscarriage is 15·3% (95% CI 12·5-18·7%) of all recognised pregnancies. The population prevalence of women who have had one miscarriage is 10·8% (10·3-11·4%), two miscarriages is 1·9% (1·8-2·1%), and three or more miscarriages is 0·7% (0·5-0·8%). Risk factors for miscarriage include very young or older female age (younger than 20 years and older than 35 years), older male age (older than 40 years), very low or very high body-mass index, Black ethnicity, previous miscarriages, smoking, alcohol, stress, working night shifts, air pollution, and exposure to pesticides. The consequences of miscarriage are both physical, such as bleeding or infection, and psychological. Psychological consequences include increases in the risk of anxiety, depression, post-traumatic stress disorder, and suicide. Miscarriage, and especially recurrent miscarriage, is also a sentinel risk marker for obstetric complications, including preterm birth, fetal growth restriction, placental abruption, and stillbirth in future pregnancies, and a predictor of longer-term health problems, such as cardiovascular disease and venous thromboembolism. The costs of miscarriage affect individuals, health-care systems, and society. The short-term national economic cost of miscarriage is estimated to be £471 million per year in the UK. As recurrent miscarriage is a sentinel marker for various obstetric risks in future pregnancies, women should receive care in preconception and obstetric clinics specialising in patients at high risk. As psychological morbidity is common after pregnancy loss, effective screening instruments and treatment options for mental health consequences of miscarriage need to be available. We recommend that miscarriage data are gathered and reported to facilitate comparison of rates among countries, to accelerate research, and to improve patient care and policy development.

Caffeine content in newborn hair correlates with maternal dietary intake

PURPOSE

High-maternal caffeine intake during pregnancy may be harmful for perinatal outcomes and future child health, but the level of fetal cumulative exposure has been difficult to measure thus far. Here, we present maternal dietary caffeine intake during the last trimester and its correlation to caffeine content in newborn hair after birth.

METHODS

Maternal third trimester diets and dietary caffeine intake were prospectively collected in Kuopio Birth Cohort (KuBiCo) using a 160-item food frequency questionnaire (n = 2840). Newborn hair was collected within 48 h after birth and analyzed by high-resolution mass spectrometry (HRMS) for caffeine (n = 316). Correlation between dietary caffeine intake and neonatal hair caffeine content was evaluated from 203 mother-child pairs.

RESULTS

Mean dietary caffeine intake was 167 mg/days (95% CI 162-172  mg/days), of which coffee comprised 81%. Caffeine in the maternal diet and caffeine content in newborn hair correlated significantly (r = 0.50; p < 0.001). Older, multiparous, overweight women, and smokers had the highest caffeine levels in the maternal diet, as well as in their newborn babies' hair.

CONCLUSION

Caffeine exposure, estimated from newborn hair samples, reflects maternal third trimester dietary caffeine intake and introduces a new method to assess fetal cumulative caffeine exposure. Further studies to evaluate the effects of caffeine exposure on both perinatal and postnatal outcomes are warranted, since over 40% of pregnant women consume caffeine more than the current suggested recommendations (European Food Safety Association, EFSA recommendations).

Key Findings and Implications of a Recent Systematic Review of the Potential Adverse Effects of Caffeine Consumption in Healthy Adults, Pregnant Women, Adolescents, and Children

In 2016⁻2017, we conducted and published a systematic review on caffeine safety that set out to determine whether conclusions that were presented in the heavily cited Health Canada assessment, remain supported by more recent data. To that end, we reviewed data from 380 studies published between June 2001 and June 2015, which were identified from an initial batch of over 5000 articles through a stringent search and evaluation process. In the current paper, we use plain language to summarize our process and findings, with the intent of sharing additional context for broader reach to the general public. We addressed whether caffeine doses previously determined not to be associated with adverse effects by Health Canada (400 mg/day for healthy adults, 300 mg/day for pregnant women, 2.5 mg/kg body weight/day for adolescents and children, and 10 g/day for acute effects) remain appropriate for five outcome areas (acute toxicity, cardiovascular toxicity, bone & calcium effects, behavior, and development and reproduction) in healthy adults, pregnant women, adolescents, and children. We used a weight-of-evidence approach to draw conclusions for each of the five outcomes, as well as more specific endpoints within those outcomes, which considered study quality, consistency, level of adversity, and magnitude of response. In general, updated evidence confirms the levels of intake that were put forth by Health Canada in 2003 as not being associated with any adverse health effects, and our results support a shift in caffeine research from healthy to sensitive populations.