Caffeine has been proposed to have all sorts of effects on health, both good and bad. Just in the last few months, it has been reported that caffeine can help repair damaged blood vessels, protect against cataract formation, and even shrink women’s breasts.
Now new research published in the British Medical Journal has found that consuming caffeine during pregnancy can increase the risk of giving birth to low-birth-weight baby. Underweight babies are more likely to be delivered early or by cesarean section, and are at a higher risk of having neurological disabilities.
The authors of this study devised a questionnaire on habitual caffeine intake that was administered before conception and twice during pregnancy in 2,635 women. They then looked at information on pregnancy complications and delivery details in the electronic databases of the two large UK maternity hospitals in which the study was conducted.
The mean caffeine intake during pregnancy in these women was 159mg a day – equivalent to approximately a cup and a half of filter coffee, three cups of tea, or about three cans of cola drink. Approximately 62% of the total caffeine ingested was in the form of tea, 14% was in coffee, 12% in cola drinks and 8% in chocolate.
Compared with women who consumed less than 100mg of caffeine a day, the risk of having a low-birth-weight baby was 20% higher in those who consumed 100-199mg per day and 50% higher in those who consumed 200-299mg per day. The size of the reduction in birth weight increased as caffeine intake increased.
Importantly, the magnitude of the association between caffeine consumption and baby size was similar to that seen between alcohol consumption and birth weight, i.e. caffeine consumption increased the risk of having a low-birth weight baby as much as alcohol consumption did.
The Food Standards Agency in the UK has now changed it’s recommendations on caffeine intake during pregnancy on the basis of this research, lowing the limit from 300mg a day to 200mg a day.
CARE Study Group (2008). Maternal caffeine intake during pregnancy and risk of fetal growth restriction: a large prospective observational study BMJ, 337 DOI: 10.1136/bmj.a2332