More than a third of US counties do not have a single medical birthing facility or the services of an obstetric clinician, causing health advocates to warn about the dangers of “maternity care deserts”, a new report says.

The report, issued by March of Dimes, an infant health non-profit, and published on Tuesday, found that 35.1% of US counties are what the group calls maternity care deserts, meaning there are no specialist medical services available to provide care.

These 1,104 counties are home to more than 2.3 million women of reproductive age, the report states, and in these counties in 2022, women gave birth to more than 150,000 babies.

The report says that women living in such care deserts and counties with low access to care are more likely to have poorer health before pregnancy, receive less prenatal care, and experience higher rates of preterm birth. Additionally, the researchers state that women in these areas face a 13% higher risk of preterm birth.

The states with the highest percent of so-called maternity care deserts were North Dakota, South Dakota, Oklahoma, Missouri, Nebraska and Arkansas, it added.