I've been taking evening primrose oil to increase cervical mucus, but i've read that it can delay ovulation. is that true?

It may: Evening primrose oil (epo) contains an omega-6 essential fatty acid, gamma-linolenic acid (gla), which is believed to be the active ingredient. Epo has been studied in a wide variety of disorders, particularly those affected by metabolic products of essential fatty acids. However, no study has show a benefit to its use in fertility. The problem with supplements is we don't know whats in them.