Pregnant- and soon-to-be-pregnant- coffee drinkers beware: a new research study shows that the probability of having a baby born at a lower birth weight was higher among women who consumed more than 100 mg, 200 mg, and 300 mg of caffeine per day as compared to women consumed less than 100 mg caffeine.
Prior to this study, we knew that caffeine does in fact cross the placenta, and we knew there was an association between coffee and lower birth weight and maybe even miscarriage. However, we did not know how much caffeine produced this effect. That is why some doctors said it is okay to have one cup of coffee per day, while some doctors advised not having any coffee. This new research study examined specific amounts of coffee and even coffee brands, and non-coffee caffeine sources. Additionally, instead of simply examining birth weight as an outcome, the researchers defined "growth restriction" taking the mother's height, weight and ethnicity, and number of previous children into account.
The research study also found:
1- Women who drank more than 300 mg of caffeine pre-pregnancy but reduced it to less than 50 mg by weeks 5-12 of pregnancy, had babies with higher birth weight than their still-coffee-drinking counterparts. So if you just found out you are pregnant, each day you decide to reduce your consumtion can help add some weight to your unborn baby.
2- Some women cleared coffee from the system faster than others. This was more dangerous for their fetus, probably because a great caffeine load came through the placenta.
3- Surprisingly, 60% of the caffeine consumed was from from tea, and only 14% was from coffee. Even more surprising, 26% of caffeine was from other sources such as cola, chocolate, and food items containing coffee, tea, cola, and chocolate such as coffee ice-cream.
To give you an idea of caffeine content, this week's grande Starbucks coffee of the week has 330 mg, a grande green tea latte (pictured above) has 80 mg caffeine, and their grande hot chocolate has 20 mg.
So, how much weight are we talking about? Women who consumed less than 100 mg of caffeine saw an increase of 2.11-2.46 ounces. While that does not sound like a lot, for an infant, it could mean a world of a difference for an already compromised fetus. Additionally, I have already discussed how low birth weight can affect later health conditions. I think the researchers sum it up best: "Sensible advice to pregnant women would be to reduce caffeine intake before conception and during pregnancy."