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. Author manuscript; available in PMC: 2013 Mar 20.
Published in final edited form as: N Engl J Med. 2013 Jan 16;368(4):333–340. doi: 10.1056/NEJMoa1207210

Figure 1.

Figure 1

Live births in Norway occurring in 2009 and 2010 were eligible for study if the date of last menstrual period occurred in or before the first 9 weeks of 2010 (43 weeks before 31 December 2009). Eligible pregnancies were defined as exposed to the influenza pandemic if any days between the date of the last menstrual period and birth occurred between 1 October and 31 December 2009. For a given pregnancy, days at risk are pregnancy days after week 12 occurring after 1 January 2009, and exposure days are defined as all pregnancy days from first day of exposure to delivery. For simplicity, the figure shows all pregnancies as lasting 9 months; study includes all registered pregnancies lasting at least 12 weeks. The period of the main wave of the influenza pandemic is shaded.