Just wanted to be sure and share this here. I have been reading up on GLAs and how they help the body create prostaglandins. I've done EPO in the past, but borage oil came up as a higher source of GLAs, so I grabbed a bottle last night to try. I didn't do enough research in hindsight, and I just decided to start taking it. I did some reading tonight, and it turns out that borage oil, along with several other herbs I already knew about, contains pyrrolizidine alkaloids (PAs) which can be teratogenic and highly toxic to your liver. Turns out a dose of 1-2 grams daily (the bottle I bought calls for three 500mg capsules daily) can be sufficient enough to be toxic. You can buy brands certified free of PAs, but many of the cheaper ones do not come that way.
In fact, several organizations have popped up saying it's teratogenic in pregnancy, despite the fact that it can definitely be linked with labor. I think I will discontinue use unless I can get a better brand, and wanted to be sure everyone else saw this. I was bummed, but also a little freaked out that I've used it at full dosage for a day now.
Here's just one link about borage. It states: "Contraindications - Pregnancy: Preliminary studies suggest borage oil has a teratogenic effect and that its prostaglandin E agonist action may cause premature labor." Prior to that it discusses the topic of PAs and toxicity.