DHA is in fish oil, and it's for baby's brain development. Some women don't like fish, or won't eat it because they're afraid of the mercury content, but the DHA in capsure form is mercury free, and has a lot of really good benefits for you and baby (if you weren't getting DHA from the pills, or from eating lots of fish, baby would just take the DHA in your body and use that, but you use it too, so you'd be in short supply).