As a thematic partner to my previous post, I thought I would quickly comment on the story in the news about two cups of coffee or more a day in pregnancy increasing the risk of miscarriage. First of all, bravo to CTV.ca for having a link to the full text article. That is a rare light in the dim world of health reporting.
The study has some problems inherent in its design in that you cannot randomly assign some pregnant women to drink lots of coffee and some to drink sugar water and see who has more miscarriages. It's not ethical. So you do what's called a cohort study. You take a bunch of pregnant women, monitor and record their various habits, nutritional and otherwise, and then follow them through pregnancy. You than look at one particular habit, like coffee consumption, and see if those with high reported levels of coffee consumption had higher rates of miscarriage than those with lower rates. The problem is that cohort studies are often plagued by lots of possible confounding factors (see previous post). Luckily this study seemed to account for them nicely.
Overall this study was well done and the press might not have totally blown it. Essentially what it found was that women who drank coffee containing 200mg or more of caffeine a day had double the rates of miscarriage compared to those who drank less than 200mg. (One 6-oz cup of coffee contains roughly 100mg of caffeine). The risk seemed to increase with the amount consumed as well.
Really though, it only confirms what experts and physicians have stressed all along: in pregnancy, moderation is everything (except in alcohol consumption, smoking, and recreational drug use; no amount is safe). Of course if you pound back 5 double espressos every day you may not be doing your baby any favors. But it looks like for now a single NORMAL size of coffee a day is no harm (stay away from my mugs though; they carry about 300mg each!)
Fine by me anyways. The less coffee my wife can drink when pregnant, the more for me!