Health authorities in India's Rajasthan state are investigating allegations that 13 pregnant women died after they were given infected intravenous (IV) fluids at a government hospital.
All the deaths were reported in Jodhpur city over the past 10 days.
Laboratory tests had confirmed that IV fluids supplied by a local company were "tainted", officials said.
A police case has been registered and an investigation has begun, they said.
"The women died after severe haemorrhaging and we believe the most likely cause might be an infection after they were administered tainted IV fluids," Umaid Hospital administrator Narendra told the BBC.
"During lab tests, we found three batches of glucose which were tainted. We have lodged a complaint with the police and strict action will be taken against the manufacturers," he said.
India accounts for the highest number of maternal deaths in the world with tens of thousands of women dying every year due to pregnancy-related problems.
Campaigners say most of the deaths are needless and could easily be prevented if more care and attention was paid to their treatment.