While Texas' infant mortality rate is lower than the national average, a new study shows wide variations in rates across different areas of the state and among different racial groups.

The study, released Thursday by the University of Texas System and UT Health Northeast, calculated infant mortality rates — the number of infant deaths under the age of 1 per 1,000 live births in a given area during the same year — for ZIP codes of communities with more than 400 births from 2011 to 2014.

“Because Texas is so big, that size can hide that we have higher rates in certain areas of the state,” said UT System Chief Medical Officer and Vice Chancellor for Health Affairs David Lakey, one of the report’s contributors. “I don’t feel reassured that our infant mortality rate is that much better than others — it’s just right at the national average — so I wouldn’t say it’s really good.”

For example, Fort Worth's 76164 ZIP code area had an infant death rate of 12.3 deaths per 1,000 births — more than six times the rate of neighboring 76107. Hispanic mothers in two adjacent ZIP codes in San Antonio, 78203 and 78220, had respective rates of 16.0 and 11.6 infant deaths per 1,000 births — both of which were higher than the state's average rate of 5.7 and the nation's average rate of 5.9.

“What this reveals is that the infant mortality picture is dramatically more complex than we knew,” Lakey said in a release. “The state average, which is lower than the national average, obscures zip codes where rates are terribly high. Some of the higher city or county level rates, on the other hand, have obscured the variation within communities, including neighborhoods where rates are very low.”

The state also saw infant mortality vary widely across ethnic groups. Black mothers had the highest infant death rates, along with the highest variation among ZIP codes, while Hispanic mothers had the lowest rates. White mothers' highest rates were outside of major metro areas — in Longview and Wichita Falls, they had twice the state’s average of infants dying.

Race isn’t the sole reason infant mortality rates may be higher or lower, Lakey said.

“It’s not something that’s just genetic,” he said. “We shouldn’t just accept that it’s a racial thing by just based by your ethnicity — there are others factors in that community that can have a profound chance that your baby will survive the first year of life.”

Deneen Robinson, program director of The Afiya Center, a reproductive justice center for black women and girls, said black women's high rates of infant mortality can stem from factors such as depression, diabetes, hypertension and substance abuse — but a principal factor is racism and discrimination in maternal health care.

"For black folks, there doesn't seem to be any protection like there are for other races," Robinson said. "When we access care, there are biases that meet us at the door. There seems to be an unwillingness to hear us."

Robinson gave an example of a young black woman she spoke with recently who continuously told her doctor she was having health issues during her pregnancy. According to the doctor, her complaints were "just a part of pregnancy" and were occurring "because she was young." After continually pressing the doctor about her health, it turned out the woman had blood clots in both her cervix and her head, which almost killed her during childbirth.

"She was young," Robinson said. "But just the fact that throughout the whole process, her visibly complaining that she was having these health concerns — and her providers were not listening to her."

Despite Texas' below average infant mortality rate, there is preventive work both state and national governments can do to help reduce the social and structural determinants of infant mortality rates, said March of Dimes Deputy Medical Officer Lisa Waddell. Measures such as group prenatal care and progesterone shots for women who’ve previously had spontaneous, pre-term births can help reduce infant mortality rates.

“We have a collective challenge, a collective goal that we want healthy moms and healthy babies, and it’s going to take all of us looking at what are those policy changes, what are those system changes that we need to work on together in order to get those healthy moms and those healthy babies,” Waddell said.

Disclosure: The University of Texas System has been a financial supporter of The Texas Tribune. A complete list of Tribune donors and sponsors is available here.