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Science or Fiction: Do Barometric Pressure Changes Really Affect Initiation of Labor?
Abstract Number: F-52
Abstract Type: Original Research
Background: A common belief is that more babies are born during storms; this is supported by the anecdotal experiences of clinicians working on Labor and Delivery units. If changes in barometric pressure (BP) can indeed initiate labor, the phenomenon could have significant implications for staffing levels on delivery units. The objective of this study was to determine if either the absolute or change in BP affects the initiation of labor and the number of spontaneous deliveries.
Methods: With IRB approval, the number of daily deliveries from 2008-2010 was obtained from Brigham and Women’s Hospital. Scheduled cesarean deliveries and inductions were excluded for this analysis. Hourly BP data for the same time period, measured at Logan International Airport in Boston (which is approximately 7.6 kilometers from the hospital), was obtained from the National Climatic Data Center database (http://cdo.ncdc.noaa.gov/qclcd/QCLCD?prior=N). For each day during the study period, the mean BP (measured in inches Hg) was calculated, as well as the magnitude of BP change during the course of that day. The ranges of daily mean BPs, and of daily upward or downward trends were divided into quartiles. The mean number of daily births in each quartile of BPs and change in BP were calculated. ANOVA tests were used to statistically evaluate these associations. A p<0.01 was considered significant to account for multiple comparisons.
Results: During the study period, daily mean BPs ranged from 29.01 to 30.62. The mean number of daily births (±SE) for each BP quartile (from low to high) were (1)10.75±0.20, (2)11.05±0.20, (3)11.04±0.22, (4)10.80±0.20; difference between groups p=0.627. For days with an upward trend in BPs, within-day fluctuations in BPs ranged from 0.05-1.00. Births for each quartile were (1)11.48±0.39, (2)10.80±0.33, (3)10.19±0.32, (4)10.31±0.33; difference between groups p=0.042. For days with a downward trend in BPs, the fluctuation range was 0.05-1.10. Births for each quartile were (1)10.99±0.36, (2)10.82±0.40, (3)11.00±0.31, (4)11.45±0.34; difference between groups p=0.617.
Discussion: There were no significant correlations between average BP or changes in BP and unscheduled births. Neither absolute BP nor change in BP appears to act as a trigger for spontaneous labor.