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

Abstract

ObjectivesCaffeine 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.MethodsDatabase 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.ResultsOf 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.ConclusionsThe 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.

A Case-Control Study on Maternal caffeine intake during Pregnancy and Risk of Low Birth Weight in Wolaita zone, Southern Ethiopia

“…While some studies have found that high caffeine intake during pregnancy increases the risk of LBW [6,7,9] other studies did not nd a signi cant association [10,19,26]. This discrepancy might be due to differences in study populations, sample size, study design, and handling of potentially confounding variables.…”

“…Caffeine can also pass through all biological membranes and freely crosses the blood-brain barrier, and the placenta in pregnant women. Maternal and fetal plasma can attain equilibrium [9]. The immature fetal liver enzyme is not capable to metabolize it, ensuing in the accumulation of caffeine in the fetus this can increase the concentration of cellular cyclic adenosine mono phosphate (cAMP), interfering in fetal cell growth and development.…”

“…furthermore, caffeine cause mainly its biological outcomes through inhibiting all kinds of adenosine receptors and increasing the catecholamine concentrations within the mother among the fetus, leading to reduced placental blood ow and hinders placental nutrient and oxygen transport to the fetus [9][10].…”

Prenatal Exposure to Alcohol, Tobacco, and Coffee: Associated Congenital Complications and Adverse Birth Outcomes

“…In our study, the consumption of three or more coffees per day was associated with increased risk of low birth weight by around twofold, which was in alignment with previous studies using the Osaka Maternal and Child Health Study (OMCHS) prospective cohort, where maternal caffeine intake was associated with a 1.28 times increased risk of preterm birth per 100 mg/d of caffeine [ 27 ]. There are frequent reports of significant dose-response associations between coffee consumption and adverse birth outcomes, implying that “moderate” caffeine consumption during pregnancy as advised by healthcare professionals may not be safe [ 28 ]. As expected, compared to babies with no prenatal secondhand smoke exposure, babies with prenatal secondhand smoke exposure had increased risk of low birth weight, as did babies born to mothers who dieted during their pregnancies.…”

Drinks and Food Caffeine Consumption and Factors Associated With Higher Intakes. A Cohort Study In Pregnant Women

“…During pregnancy, the maximum limit of caffeine intake recommended should be 200 mg/day [8,9]. Findings from observational studies and meta-analyses indicate that maternal caffeine consumption is reliably associated with miscarriage, stillbirth, low birth weight and/or small for gestational age, childhood acute leukemia and childhood overweight and obesity [10,11]. Recently, it has been associated in Korean pregnant women a higher risk of bleeding in early pregnancy among those with heavy coffee consumption (2 cups of coffee/day) before pregnancy [12].…”