That article says abstinence only education wasn't a factor in 1990 even though the AFLA act was passed in 1981, so that kind of blows the article's main argument right out of the water, along with their credibility.
In regards to the "abortions skewing birth rate results" argument, I was going to look at teen pregnancies to compare, but I'm actually having trouble finding pregnancy rates by state, as opposed to birth rates, because articles like this call it "Teen pregnancy rates" even though the states are ranked by live births of 15 to 18 year olds.
https://www.livescience.com/27417-teen- ... state.html
1. New Mexico - 93/1,000
2. Mississippi - 90/1,000
3. Texas - 85/1,000
4. Nevada - 84/1,000
5. Arkansas - 82/1,000
6. Arizona - 82/1,000
7. Delaware - 81/1,000
8. Louisiana - 80/1,000
9. Oklahoma - 80/1,000
10. Georgia - 78/1,000
So I don't think there's good evidence for your original claim that sex education causes pregnancy. I think at best you can say there's cultural and socioeconomic factors that may have more influence on things than sex education policies. But without a doubt, a culture where abortions are frowned upon and less used means more teens unlucky enough to get pregnant will be trapped into parenthood and likely poverty.
Also, I would be interested to see a no bullshit source for PP saying it's "okay"/encouraging teens to have sex. I don't consider informing teens on biology and risk management to be encouragement by the way.