Participants were consented but registry was not developed due to low numbers

The goal of this study it to rapidly create a brief registry of pregnant women who receive the H1N1 vaccine in Ontario, British Columbia, and Nova Scotia during the pandemic H1N1 2009/2010 influenza season.

For Part 1, a brief amount of data will be collected on each woman at the time of her vaccination. These data will be filled out on a single data collection sheet by her Obstetrics Clinic physician or nurse, which will be completed at the time of her vaccination.

For Part 2, after a woman's expected delivery date, data sources will be used for participants. Two groups of non-vaccinated controls will be derived from the provincial perinatal databases:

1. The active non-vaccinated controls will be recruited from the concurrent year, matched to women who were vaccinated in 2009/2010. For each of the three perinatal databases, 5 non-vaccinated active controls will be matched by maternal age +/- 3 years, same-hospital delivery, and delivery date +/- 7 days.
2. The passive non-vaccinated controls will be derived from the preceding year (i.e., 2008). For each of the three perinatal databases, 5 non-vaccinated passive controls will be matched by maternal age +/- 3 years, same-hospital delivery, and delivery date +/- 7 days.

For women who delivered in Ontario, the Niday Perinatal Database will be used. (https://www.nidaydatabase.com/info/index.shtml).

For women who deliver in British Columbia, their data will be linked to the British Columbia Perinatal Database Registry (http://www.bcphp.ca/Database%20Content.htm). Women who deliver in Nova Scotia will be linked to Nova Scotia Atlee Perinatal Database (http://rcp.nshealth.ca/rcp\_3347.html).

Information that will be obtained is as follows:

• Actual delivery date (DD/MM/YYYY)
• Number of infants delivered
• Mode of delivery (vaginal for Caesarean)
• Liveborn or stillborn
• Presence of a congenital anomaly
• Presence of intrauterine growth restriction or small-for-gestational age birthweight
• Presence of a neonatal infection
• Presence of neonatal sepsis
• Need for ventilation of the neonate
• Need for Neonatal Intensive Care of the Neonate.

For Part 3, between 18-24 months after a woman's actual delivery date, a woman may be telephoned at her home to ask her about the health and developmental milestones of her baby. This phase may or may not be done, but consent will be obtained nonetheless.

Inclusion Criteria:

• Received the H1N1 vaccine during pregnancy

Exclusion Criteria:

• None

Pregnant women who recieved the H1N1 vaccine during pregnancy in 2009.