In this Tuesday, Feb. 3, 2015 photo, Genetha Campbell carries free water being distributed at the Lincoln Park United Methodist Church in Flint, Michigan. AP Photo/Paul Sancya Fetal deaths rose and fertility rates dropped after Flint, Michigan switched to lead-poisoned water.

That is according to a new working paper by economists Daniel Grossman of West Virginia University and David Slusky of Kansas University.

The authors found that fetal deaths — pregnancies that lasted at least 20 weeks but did not result in a birth — increased by 58% and fertility rates fell by 12% in Flint after April 2014 compared to rates in other economically-similar Michigan cities that didn't switch their water sources.

They estimate 198 to 276 more children would have been born among babies conceived from November 2013 to March 2015 if Flint did not switch water sources.

"Failure to provide safe drinking water has large health implications," Grossman and Slusky wrote in the conclusion.

Comparing Flint to other economically similar cities in Michigan provided a "natural control group," they said. And since it wasn't known that the new water supply had higher lead content, they argue the decrease in the general fertility rate was more likely to be reflection of fetal deaths and miscarriages than a change in sexual behavior.

The authors also listed several limitations their study had. Since lead builds up in the body over time, their focus on neonatal health might underestimate lead's overall affects on human health and development. Further, other contaminants in the water could have also affected the results.

"Despite these limitations, the culling of births in Flint provides robust evidence of the effect of lead on the health of not just infants, but on the health of potential newborns in utero."

Back in April 2014, in an effort to save money, Flint's emergency manager switched the city's water source from Lake Huron to the Flint River. The water from the river was more corrosive, however, and "caused lead to leach from city pipes" into drinking water, according to Reuters. The city said the Flint River was safe to drink as late as 2015, and the water source was eventually switched back in October 2015.

Lead is a cumulative toxin that affects multiple body systems, according to the World Health Organization. It is associated with an increased risk of high blood pressure and kidney damage. Young children who are exposed to lead can suffer issues related to brain and nervous system development.

There's no known level of lead exposure that's considered safe, according to the WHO.

Previous studies have found a correlation between a mother's lead exposure and fetal death, prenatal growth abnormalities, reduced gestational periods, and reduced birth weights, as the economists noted in their paper. According to the Centers for Disease Control and Prevention (CDC), "lead can cross the placental barrier, which means pregnant women who are exposed to lead also expose their unborn child."

Check out the full working paper here.