Evening Primrose Oil

Deena
Moms and moms-to-be were talking about this product about a week ago and I heard great things about it, so I decided to get it! I'm 36 weeks and excited to prepare my body for labor, but when the bottle arrived from Amazon it says "not for pregnant or breastfeeding women". Do I need to speak to my doc before using it? Is there a reason there's a warning on it?