Caffeine intake and fetal health

Caffeine and fetal growth

Studies of caffeine and fetal growth restriction are equivocal. Some studies showed no effects on growth, whilst others demonstrated a risk of growth retardation with increased exposure to caffeine, although with the inability to determine the role of confounding factors^1,13.

One of the larger studies was the Dutch Generation R Study, a prospective cohort study which included 7,346 pregnant women. Inconsistent associations were observed between caffeine intake and fetal head circumference, or estimated fetal weight. Higher caffeine intake (over 540mg caffeine daily) was associated with shorter birth length, suggesting that fetal growth may be impaired by caffeine³⁵. However, further studies are needed to assess these associations in non-European populations and the possible postnatal consequences of the observed fetal growth restriction. Results from a large prospective cohort in which the main caffeine source was coffee, showed that coffee but not caffeine, was associated with marginally increased gestational length but not with spontaneous preterm delivery²⁹. However, caffeine intake was consistently associated with decreased birth weight and increased odds of the baby being small for its gestational age²⁹.

The 2010 Committee Opinion of the American College of Obstetricians and Gynecologists stated that the relationship between caffeine and growth restriction remains undetermined³⁴.

A 2015 meta-analysis reviewing the associations between caffeine consumption and risk of low birth weight concluded that for every additional 100mg of caffeine per day the risk of low birth weight increased by 3%³⁶.

A further 2015 Cochrane review of the effect of restricting caffeine intake by mothers concluded that there is insufficient data to confirm or refute the effectiveness of caffeine avoidance on birthweight or other pregnancy outcomes³¹.

Caffeine and congenital malformations

Brent et al. concluded in their risk analyses that it is very unlikely that regular or even high exposures to dietary caffeine increase the risk of birth defects for pregnant mothers exposed to caffeine¹³. With a few exceptions, studies have not reported an increased risk of malformations with greater caffeine consumption.

One paper reported weak positive associations between maternal caffeine consumption and spina bifida (neural tube defects), but without a dose-effect relationship and with a negative association for tea. However, the control for confounding by smoking and alcohol (both yes/no answers only) was insufficient¹⁴. A further case-control study, with 776 cases and 8,756 controls, looked at the risk of spina bifida and maternal cigarette, alcohol, and coffee use during the first month of pregnancy. It found that levels of cigarette smoking (1-9 and ≥ 10/day), alcohol intake (average ≥4 drinks/day) and caffeine intake (<1, 1, and ≥2 cups/day) were not likely to be associated with increased risk of spina bifida¹⁵. The same research group raised the issue that gene variants like slow/fast caffeine metabolisers may run different risks¹⁶.

A further meta-analysis published in 2015 considering maternal coffee consumption and the incidence of neural tube defects (NTD), suggested that maternal coffee consumption during pregnancy was not significantly associated with the occurrence of total NTD or the spina bifida subtype of NTD¹⁷.

A 2011 study, evaluating data from the National Birth Defects Prevention Study, examined the association between maternal caffeine consumption (from coffee, tea, soda and chocolate) and the risk of selected birth defects. The cohort of 3,346 cases was matched with 6,642 controls. The research did not suggest an association between maternal caffeine intake and the birth defects¹⁸. A further study, also evaluating data from the National Birth Defects Prevention Study, assessed associations between maternal dietary caffeine intake and congenital limb deficiencies. In this study, with 844 cases and 8,069 controls, high soda consumption was associated with an elevated risk for longitudinal limb deficiencies. Coffee and tea consumption was not associated with any limb deficiency subtype¹⁹.

Caffeine and fetal death

Four studies detailed in a review of data gathered between 2000 and 2009 evaluated the relationship between caffeine and fetal death¹. Three of the studies were conducted by the same research group, in which two reported a moderately positive association and the third found no relationship. The fourth study also noted a positive association. None sufficiently address the concerns regarding confounding by pregnancy symptoms. As with studies of miscarriage, the interpretation of the work on caffeine and fetal death needs to consider that these studies may also share common sources of bias which may explain the observed relationship with caffeine use¹.

Maternal coffee consumption and childhood leukemia

There are limited studies in this area, and while some research suggests an association between consumption of coffee during pregnancy and subsequent increased risk of childhood leukemia, more research is needed to better understand this. Pregnant and breastfeeding women are advised by EFSA to drink no more than 200mg of caffeine per day from all sources, which is equivalent to 2-3 cups of coffee⁵.

In 2016 IARC reviewed data on childhood leukemia in relation to coffee consumption and concluded that a lack of consistency amongst studies led to inconclusive and inadequate evidence of any association between coffee consumption and childhood leukemia³⁷.

• Authors of a 2015 meta-analysis comprising a total of 3,649 cases and 5,705 controls concluded that their findings “confirm the detrimental association between maternal coffee consumption and childhood leukemia risk, and provide indications for a similar role for maternal cola consumption”³⁸

• A further study published in 2015 examining parental smoking, maternal alcohol, coffee and tea consumption during pregnancy, and childhood acute leukemia concluded that childhood acute leukemia was not associated with coffee consumption during pregnancy, but an association was seen between coffee consumption and acute lymphoblastic leukemia³⁹

• A 2018 review of data on maternal coffee intake in 2,552 cases and 4,876 controls suggested that coffee intake over 2 cups per day during pregnancy may increase risk of childhood acute lymphoblastic leukemia, although the authors acknowledged that there were limitations in the research. They supported current advice to limit caffeine intake during pregnancy⁴⁰