Stretch marks come from rapid weight gain and the severity of them is thought by some to be influenced by heredity and by how much moisture is in the skin when it is doing all this stretching.
The skin of the lower back doesn't stretch as much as the abdomen in pregnancy, but it's really hard to control how much weight you might gain while pregnant or how fast. If you got stretch marks on your lower back with this first pregnancy, you can pretty much bet it's going to happen with any pregnancies you might have in the future.
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Tattooing and Pregnancy