Date of Award
Master of Public Health (MPH)
Dr. Gerardo Chowell
Dr. Ruiyan Luo
INTRODUCTION: Influenza pandemic of 1918 was the most devastating pandemics to date, affecting approximately one-third of the population worldwide. Prior works have documented the impact of the 1918 influenza pandemic on pregnant mothers and pregnancy outcomes like birth defects, miscarriages or preterm births, but the impact of infection on stillbirth is not studied well.
OBJECTIVE: To assess the stillbirth risk due to the 1918 influenza pandemic in Arizona, USA.
METHODS: We conducted a retrospective study to assess the impact of the 1918 influenza pandemic on stillbirth risk. We manually retrieved 21,334 birth records for the Maricopa County of Arizona state for the years 1915-1925 from a publicly available genealogy database. Logistic regression using SAS statistical software was done to assess the impact of influenza on the risk of stillbirth. Additionally, the study evaluated the risk of stillbirth with advanced maternal age.
RESULTS: The results did not show a significant impact of a pandemic on stillbirth risk. January 1920 experienced the highest rate of stillbirths with 59 stillbirths per 1000 births, 9-10 months later, the deadly second pandemic wave. There was also a higher rate of stillbirth in July 1919, with 49 stillbirths per 1000 births.
Additionally, there was a significant association between stillbirth and advanced maternal age (P-value 0.0096, at 0.05 level of significance) with stillbirth risk of 1.42 (95% Confidence interval: 1.17, 1.72) in younger women (<35 yrs.) compared to older women (≥35 yrs.). The results showed that the risk of stillbirth is least if the age of the mother is approximately 26 years at the time of pregnancy.
DISCUSSION: Though the results did not show a significant impact of the pandemic on stillbirth risk, the study did observe a higher rate of stillbirth in July 1919, consistent with natality decline reported in the previous study in the same month in Arizona. Also, the results are in line with prior work and found that there is a high risk of stillbirths with advanced maternal age.
Khare, Smriti, "Stillbirth Risk during the 1918 Influenza Pandemic in Arizona, USA.." Thesis, Georgia State University, 2020.
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