A recent Stanford University study indicates that crackdowns on unauthorized immigration may interfere with the development of unborn children.

The study, conducted by the sociologists Florencia Torche and Catherine Sirois, analyzed fertility data from years before and after the April 2010 signing of S.B. 1070, a controversial Arizona law that originally mandated that law enforcement officers verify the immigration status of anyone they stopped. The bill, which was largely blocked by a court decision, would have also required noncitizens to carry proof of immigration status and made it a crime to hire anyone without a work permit. While the court blocked most of the law’s provisions, officers can still ask about legal status at their own discretion.

The study found Latina immigrant women in Arizona who were pregnant during the contentious debate over S.B. 1070 and gave birth in the six-month period between July and December 2010 had babies with lower birthweight compared with those in prior years. Average birth weights did not decrease among U.S.-born white, black or Latina women during the same time.

“It is the fear itself that can have a negative effect on women,” Dr. Torche said in an interview with America. She said the impact on birthweight began before the partial implementation of the law.

Prior research has found that birthweight is an indicator of health, including morbidity, cognitive development and behavioral function, Dr. Torche said. Environmental stressors, from natural disasters to wars, have a negative impact on pregnant mothers, she said.

The number of births among Latina immigrants in Arizona during the second half of 2010 also decreased. While the data does not specify the reason, the decrease in births could be explained by a number of factors, including intentional delay of pregnancy, miscarriage or abortion.

Joe Rubio, senior organizer for the West/Southwest Industrial Area Foundation, said “nativist” legislation, like S.B. 1070 “was meant to scare people out of the state. The intention was to turn us against each other, especially the ‘show me your papers’ dimension of the bill.”

Immigration enforcement laws of that time sowed mistrust and suspicion in communities, Mr. Rubio said, noting that a number of parishes in Phoenix saw Mass attendance and community participation plummet. Children would call their homes after school to see if it was “safe,” he said, explaining it was considered dangerous if police officers were in the neighborhood.

“Who’s going to report crimes? Mean-spirited legislation affects not only this generation but generations to come,” he said. “You are hurting citizen children, future workers and, from a larger perspective, you’re damaging the body of Christ. We pursue this type of fear-based legislation to our peril.”

Children would call their homes after school to see if it was “safe,” he said, explaining it was considered dangerous if police officers were in the neighborhood.

Donald Kerwin, the executive director of the Center for Migration Studies, said that the debate around S.B. 1070 “was the most heated… of any bill at the state level.” The law served as a model for a number of other states that wanted to implement immigration enforcement reforms, he said.

On a national level, Mr. Kerwin noted that recent immigration enforcement measures have had a negative impact on children of all ages.

“Some, who have had one parent deported, are frightened their remaining parent will be taken and their lives will be upended,” he said, citing another recent study. “Not only is their family separated, but they have to move and live an impoverished life.”

Older children feel the burden of assuming an adult role in the household, Mr. Kerwin said. The older siblings will serve a parental role and, in many ways, lose their childhood.

“These are two groups, young and older kids, that suffer because of harsh immigration enforcement laws like S.B. 1070,” he said. “We have the full cycle of children that are negatively affected, from in utero to teenagers.”

Those born in the United States are citizens, including the majority of those children whose parents are deported, Mr. Kerwin noted.

“Children are the ones taking the heat,” he said. “You feel you’re at risk and you’re not wanted and not a full member of your community. It’s just a terribly harmful environment for children.”

“These are two groups, young and older kids, that suffer because of harsh immigration enforcement laws like S.B. 1070,” he said. “We have the full cycle of children that are negatively affected, from in utero to teenagers.”

Dr. Torche also emphasized that Trump administration policies on immigration could be harmful to children and pregnant mothers. But she also said a nurturing community can help restore balance.

“These networks can counteract the effects of negative experiences,” she said. “Communities can be deliberate in developing these support networks. I hope that is taking place.”

Material from Catholic News Service was used in this report. This article was updated since initial publication to give more precise details of the Stanford University study.

J.D. Long García is a senior editor at America.