Dr. Verena Sengpiel, from Sahlgrenska University Hospital, Sweden, and colleagues reported the first definitive study that links the amount of caffeine a mother consumes during pregnancy with their babies birth weight but also connects caffeine use with the baby being small for gestational age at birth in the open access journal BMC Medicine on Feb. 18, 2013.
The researchers examined over 60,000 pregnancies and eliminated other known causes of low birth weight like from the study.
All sources of caffeine were included in the ten year monitoring study. Caffeine sources are coffee, tea, chocolate, and cocao containing foods.
“For a child of expected average weight (3.6 kg) this equates to 21 to 28 grams lost per 100 mg caffeine per day. It was not just caffeine, but the source of caffeine, which affected pregnancy outcomes. Caffeine from all sources increased the length of the pregnancy by 5 hours per 100 mg caffeine per day, but caffeine intake from coffee was associated with an even longer gestational length - 8 hours extra for every 100 mg caffeine per day.”
The same affects were not seen in tea drinkers indicating another chemical in coffee can pass the placental barrier like caffeine and affect the term of pregnancy.
The present recommended daily limits for caffeine consumption during pregnancy range from 200 mg per day to 300 mg per day - about one cup of coffee.
Small for gestational age at birth babies are subject to higher risk of both short term and lifelong health problems.