New Delhi, Nov. 8 -- More American parents are declining the vitamin K injection routinely offered to newborns, and two large new studies associate the trend with higher rates of serious infant bleeding. The findings were published November 5 in JAMA and JAMA Pediatrics.

A rising share of newborns without the shot

The JAMA study, led by researchers at Children's Hospital of Philadelphia, analyzed records for about 5.2 million infants born from 2017 through 2025. ABC News reported that the share of babies who did not receive the shot rose from 3.1% in 2017 to 6.8% in 2025, including an increase from 5.6% in 2024.

The JAMA Pediatrics study examined records for more than 11 million infants and found a similar pattern. According to the Sta...