Sampling times and epidemic curve.

<p>Sampling times of serologic survey (Jan 1–Mar 28, 2010) shown relative to epidemic curve of pH1N1 cases and percent of ILI (influenza-like illness, ILI %) accounted for out-patient and emergency cases.</p

Ages and gestational weeks of pregnant women when serum samples were collected.

<p>*Kruskal-Wallis Test.</p

Seropositive rates of antibodies against pH1N1 in pregnant women and voluntary blood donors at the 4 sampling times.

<p>Seropositive rates, Proportion of titers of 1∶40 or more (%).</p><p>*Chi square tests.</p>†<p>Cochran-Armitage test.</p