Teen Pregnancy and Statutory Rape

I was surprised to come across a study (using 1988 data, teen pregnancy has fallen greatly since then and this could have a big impact on the mix of data) which concluded that "Only 8% of all births to 15 to 19-year-olds are to unmarried minors with a partner five or more years older." A significant share of teen pregnancies involving much older men are to married teens. This suggests given recent teen birth rate data that the number of unmarried teen mothers who give birth in relationships with men at least five years old is on the order of 3 per 1000 teenaged women. This would be about two cases per year of teen births arising from statutory rape in a high school the size of the one I attended growing up.