According to the essential Louise Norris, there are currently just six states where being pregnant in and of itself makes someone eligible for a Special Enrollment Period outside of the official Open Enrollment Period:
In most states, pregnancy does not trigger a special enrollment period. HHS considered this, but clarified in 2015 that they had decided not to include pregnancy as a qualifying event. This means that in most states, the special enrollment period tied to having a baby does not begin until the baby is born.
But state-run exchanges (there are 18 of them as of 2022) can set their own rules for qualifying events and special enrollment periods. Some of them do allow a special enrollment period triggered by pregnancy. This gives a pregnant person access to health coverage during the pregnancy, rather than having to wait until the baby is born to obtain coverage. As of 2022, pregnancy is a qualifying event in the following state-run exchanges:
CMS Commits Over $49 Million to Reduce Uninsured Rate Among Children and Boost Medicaid Enrollment Among Parents, Pregnant People
The Centers for Medicare & Medicaid Services (CMS) committed a record $49.4 million to fund organizations that can connect more eligible children, parents, and pregnant individuals to health care coverage through Medicaid and the Children’s Health Insurance Program (CHIP). Awardees—including state/local governments, tribal organizations, federal health safety net organizations, non-profits, schools, and others—will receive up to $1.5 million each for a three-year period to reduce the number of uninsured children by advancing Medicaid/CHIP enrollment and retention.