Context Infection with 2010 H1N1 influenza A virus usually causes a mild self-limiting upper respiratory tract illness in healthy adults.1 Studies of the effects of 2009 H1N1 on pregnant women demonstrated increased rates of preterm and operative delivery.2 Pregnant women were more likely to suffer significant morbid sequelae than non-pregnant women.2 3 Scant data exist for the effects of 2010 H1N1 influenza A on pregnant women.

Methods We conducted a retrospective review of all women with confirmed pregnancy and H1N1 influenza A virus detected on PCR testing at a large central London teaching hospital. Outcome measures included length of stay, ICU admission, the need for ventilatory support, gestation at delivery, mode of delivery and the time from admission to initiation of therapy with a neuraminidase inhibitor.

Results 29 pregnant women were admitted to our institution during the 2010 – 2011 pandemic with PCR-confirmed H1N1 influenza virus A. Seven percent (n=2) required admission to intensive care and one required invasive ventilatory support. There were no deaths. 17% of the women (n=5) delivered preterm of whom two delivered infants before 34 weeks gestation. There were no intrauterine or neonatal deaths. 51% (n=16) of pregnancies were delivered by caesarean section. All women received oseltamivir within 24 hours of admission to the hospital.