Health Risk Assessment for Postnatal/Postpartum Screening

According to the Affordable Care Act, insurances should now be paying for the Health Risk Assessment for Postpartum Depression. Does anyone know how this should be billed? Is this supposed to be billed under the mom or the infant? The code we use is CPT® 99420, is there a modifier we need to append? Any help on how this is to be billed would be greatly appreciated. Thank you.