H1N1 in pregnancy: a tertiary care centre experience

To elucidate factors pertinent to the course and outcome of H1N1 infection in pregnancy.

We conducted a retrospective chart review of H1N1-affected pregnant patients at Mount Sinai Hospital in Toronto, Ontario. All women who tested positive for H1N1 from June 1, 2009, to December 5, 2009, were identified. Records were reviewed to determine pregnancy status. Information from clinic and hospital charts of pregnant patients was gathered using data collection forms previously approved by the Mount Sinai Hospital Research Ethics Board.

Of 42 patients, 12 were inpatients and 30 were outpatients. Sixty percent of patients (25/42) presented in the third trimester, 33% (14/42) had comorbidities, and 69% were afebrile and therefore did not have a condition that met the United States Centers for Disease Control and Prevention's definition of influenza-like illness. Antiviral agents were administered promptly in most patients, but delays resulted in one third of patients being treated more than 48 hours from the onset of symptoms. Seventy-one percent (30/42) did not require hospitalization, and 58% of hospitalized patients (7/12) were admitted for reasons unrelated to H1N1. Although one quarter of hospitalized patients (3/12) had delivered at the time of discharge, no deliveries occurred because of H1N1. Most patients (91%) delivered at term. One half of the deliveries (51%) were by Caesarean section, but none of these were because of H1N1 infection. Most of the infants (88%) were appropriately grown, and none were admitted to the NICU because of H1N1.

Infection with H1N1 in pregnant women has the propensity to result in significant maternal and fetal morbidity and mortality, and requires vigilance in assessment and prompt treatment. In contrast to reports published to date, our cohort experienced a largely uncomplicated course of illness, with minimal fetal and maternal impact in most instances.