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Researchers studying Flint lead water crisis found a decrease in pregnancies and an increase in fetal deaths among Flint women. Fertility rates dropped by 12% while fetal deaths rose by 58%.

David Slusky from Kansas University and Daniel Grossman from West Virginia University analyzed health records from 2008 to 2015, focusing on women of child-bearing age in Flint and 15 other large Michigan cities, including Detroit. They then calculated the birth rate for each city by looking at the number of live births.

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Researchers found a decrease in pregnancies and an increase in fetal deaths among Flint women after the city's lead water crisis.

The crisis began in 2014 when, in an effort to save money, the city of Flint Michigan switched its drinking water supply from the city of Detroit to the Flint River. Unfortunately, they didn’t add the necessary anti-corrosives. What ensued was a spike in the amount of lead in drinking water, exposing thousands to unsafe and even poisonous lead levels.

In addition to health records, the team also looked at data indicating that Flint residents had waited to have children—either by analyzing Google searches for “lead” and “lead poisoning” or reports of less sexual activity during the time period. They didn’t find anything until September 2015, when local government and health officials acknowledged the problem.

The researchers’ findings reported that on average, babies who came to full term in Flint were born more than five ounces (nearly 150 grams) lighter than in other areas. They were also born a half-week earlier, gained 0.18 ounces (five grams) less per week, and skewed more female.

“Male fetuses are more fragile and more susceptible to fetal shocks,” Grossman said. “That we find a lower ratio of male to female births suggests to us that fetuses were affected by the water change and that female fetuses came to term more often than male fetuses.”

Data on fetal death rate is more limited since state statistics are kept only for fetuses that die after 20 weeks and in a hospital.

“I am not surprised,” said Dr. Mona Hanna-Attisha, director of Pediatric Residency Program at Hurley Medical Center in Flint, Michigan, in an email. “We have known for centuries that lead impacts the unborn.”

The damage of lead poisoning is irreversible, and it’s most pronounced in the developing brains and nervous systems of children and fetuses. It can lead to decreased bone and muscle growth, lower intelligence, and behavioral problems. But it affects children and fetuses differently.

At the turn of the 20 th century, pharmacists would sell lead pills to women to end unwanted pregnancies. Lead affects the health a fetus directly, given that it passes through the placenta. This means the fetus may not come to full term, reducing birth rates, as was found in the study.

What exactly went wrong in Flint—and what does it mean for the rest of the country?

While the long-term impact of Flint’s decreasing birth rate is hard to predict, the effects of lead exposure causes severe life-long damages to children and fetuses’ neural development.

“Negative health shocks suffered in utero may affect latent health,” Grossman said. “This group of children exposed to lead in utero may be more susceptible to hypertension or cardiovascular disease in middle age.”

Dr. Hanna-Attisha has been working on building a registry in Flint to connect people who have been exposed to lead with resources and programs to improve their health. “Since we have realized the widespread crisis, my focus has been moving forward: protecting children from the impact of the crisis/trauma—building resilience, hope, programs and interventions that promote children’s health and development,” she said.

This post has been updated to include a comment from Dr. Mona Hanna-Attisha.