Study shows miscarriage risk may have increased after flu shots, puzzling researchers

Sometimes when scientists study things, they come up with results they didn’t expect, can’t explain, and may secretly wish they’d never sought. A new journal article looking at whether getting a flu shot during pregnancy increases a woman’s risk of miscarrying may be one such case.

The article reports that at least in the 2010-11 and 2011-12 influenza seasons, pregnant women who were vaccinated against flu may have been at a higher risk of suffering a miscarriage — but only if they had also received a flu shot in the previous year as well.

The results, published Wednesday in the journal Vaccine, are puzzling and contradict earlier research. A study conducted by the same scientists about a decade ago looked at this question and concluded there was no miscarriage risk from getting a flu shot.

The new finding raises a lot of questions and is sure to provoke concern among pregnant