Here is what changes in practice. For a long time, the pregnancy episode has been billed as a bundle. You would see the patient across the pregnancy episode, stack up the antepartum visits, and then bill once at the end, upon delivery, and get paid for the whole episode, absent a specific payer contract that said otherwise.
The new world looks more like bill-as-you-go. You still see the patient over the course of the pregnancy, but each encounter is billed separately, as an E&M visit plus modifiers, with details that reflect how far along the pregnancy is, any complications, and any specific procedures provided during that episode.
This is not just a future event. Some payers have already flipped. Molina of Florida began transitioning as early as March, and Aetna moved on September 1. Aetna, for example, now asks that preventive prenatal visits for patients expected to deliver in 2027 be billed with the applicable E&M code plus a modifier and a pregnancy diagnosis code when three or fewer visits occur before January 1, 2027. The patients you are seeing today may already fall under the new rules for some payers.
One more unique thing about this transition. CMS has proposed a G-code that would substitute for the old global codes: https://www.federalregister.gov/documents/2026/07/16/2026-14327/medicare-and-medicaid-programs-cy-2027-payment-policies-under-the-physician-fee-schedule-and-other. This isn't finalized yet, but if it does get finalized, OBGYNs and hospital maternity groups will not only have to deal with multiple payer transitions, they will have to deal with maintaining a separate billing framework for medicare only .
As of now, that is still a proposal and most payers are silent on it.
If maternity is a meaningful part of your practice, now is the time to understand what is changing, because many of the patients you are seeing today will deliver after the switch.
To track which payers have transitioned and how, we keep a free Maternity Resource Center: https://www.substrateai.com/payers/2027-substrate-maternity-resource-center
