The research, published in BMC Medicine, investigated the impact of maternal caffeine consumption on health outcomes of babies in almost 60,000 pregnancies – finding that caffeine intake is consistently associated with decreased birth weight (BW) and increased odds of the baby being small for gestational age (SGA).
“In this study we found no association between either total caffeine or coffee caffeine and preterm delivery but we did find an association between caffeine and SGA,” explained Dr Verena Sengpiel from Sahlgrenska University Hospital in Sweden, who led the project.
“This association remained even when we looked only at non-smoking mothers which implies that the caffeine itself is also having an effect on birth weight."
Indeed, the research team found that caffeine from all sources – including coffee, tea, soda drinks, as well as food including cocoa-containing cakes and deserts and chocolate – reduced birth weight by up to 28 grams for each 100mg of caffeine consumed each day.
Caffeine from all sources was found to increase the length of the pregnancy by five hours per 100mg caffeine per day, but caffeine intake from coffee was associated with an even longer gestational length – adding an additional 8 hours to pregnancy for every 100mg of caffeine per day.
Sengpiel and her team analysed data from 59,123 women with uncomplicated pregnancies giving birth to a live singleton baby.
Caffeine intake from different sources was self-reported at gestational weeks 17, 22 and 30 and then analysed against pregnancy results including incidence of spontaneous pre-term delivery (PTD), birth weight (BW) and the baby being small for gestational age (SGA).
The team found that for a child of expected average weight (3.6kg) each 100mg of caffeine consumed per day equates to between a 21 gram and 28g reduction in birth weight.
However, it was not just caffeine, but the source of caffeine, which affected pregnancy outcomes, said Sengpiel.
Maternal nutrition is important to a developing embryo and to the health of the child later in life, for example supplementation with vitamins such as folic acid are known to have a large impact on the development of the foetus – by reducing the risk of spina bifida in the case of folic acid.
However, the researchers warned that not everything may be beneficial to a developing baby in this way. Previous research has linked alcohol consumption, intake of trans-fats, acrylamide and salt, with negative health outcomes during pregnancy.
The World Health Organisation (WHO) currently suggests a limit of 300mg of caffeine per day during pregnancy, however some countries recommend a limit of 200mg.
The researchers noted that SGA babies are at higher risk of both short term and lifelong health problems. Based on the results of their study, the team argued that since even 200 to 300mg of caffeine per day can increase the risk of SGA by almost a third, such recommendations need to be re-evaluated.
Source: BMC Medicine
Published online ahead of print, doi: 10.1186/1741-7015-11-42
“Maternal caffeine intake during pregnancy is associated with birth weight but not with gestational length: results from a large prospective observational cohort study”
Authors: Verena Sengpiel, Elisabeth Elind, Jonas Bacelis, Staffan Nilsson, et al