It's the weirdest sign that you may be expecting:

In fact, says author Sera Young, in some cultures eating dirt is the go-to pregnancy "gotcha" symptomthe same way that every American knows to suspect a woman who pukes in the morning, or wants pickles with her ice cream.

That's really where a lot of the fascination comes from for me. Why is this tendency so specific to pregnant women? And why does the frequency of pica vary depending on location? Even though people do this all over the world, studies have shown some big differences between populations. For instance, Young writes, .01% of pregnant Danish women eat dirt, but 56% of pregnant Kenyan women do.