(CNN) Pregnancy-related deaths can happen up to a year after birth and are preventable in the majority of cases, according to a new report. These deaths include those caused by a pregnancy complication, events triggered by pregnancy or the worsening of an underlying condition due to the effects of pregnancy on the body.

Researchers at the US Centers for Disease Control and Prevention analyzed national data reported to the agency's Pregnancy Mortality Surveillance System between 2011 and 2015. They also examined detailed data from the Maternal Mortality Review Committee in 13 states gathered between 2013 and 2017.

From 2011 to 2015, there were a total of 3,410 pregnancy-related deaths in the United States, consistent with known rates of about 700 deaths per year. Nearly 31% of the deaths in the study happened during pregnancy, 36% happened the day of delivery or the week after, and 33% happened one week to one year after delivery, according to the findings, published Tuesday in the CDC's Morbidity and Mortality Weekly Report

"We really wanted to know more about the timing of death," said the report's lead author, Dr. Emily Petersen, medical officer and ob-gyn in the CDC's Division of Reproductive Health.

"I think, a lot of times, people might think that pregnancy-related deaths occur just around delivery, but we actually also see that pregnancy-related deaths happen before, during and up to one year after delivery," she added.

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