(NewsNation) — A newborn died after its mother crossed the border in Arizona and was taken to a local hospital for evaluation, Customs and Border Patrol announced.

The mother was part of a group of 12 migrants who crossed into the U.S. near Lukeville, Arizona, and were apprehended by Border Patrol agents in February. The pregnant woman was from Angola and did not speak English and was speaking what agents believed was French.

She was taken to the Ajo Station for booking, where a nurse practitioner noted the woman complaining of abdominal cramping and back pain. The woman believed she was around eight months pregnant and had not had a prenatal visit in more than three months.

The woman, who denied taking any medications, had suffered two previous miscarriages. An ambulance was called to take her to a nearby hospital for additional care.

At Abrazao Hospital West Campus in Goodyear, Arizona, just over 100 miles away, doctors detected a defect in the fetal heartbeat. The woman underwent an emergency cesarean section, but the newborn’s heartbeat was low and falling after delivery.

Medical staff were not able to resuscitate the newborn after an hour of attempts, and the baby was declared deceased.

The Maricopa County Medical Examiner’s Office performed an autopsy on the newborn and the results are pending.

The agency announced that the incident is being reviewed internally and that the Department of Homeland Security Inspector General was notified of the incident.