Rates of congenital anomalies and other adverse birth outcomes in an offspring cohort of registered nurses from British Columbia, Canada.

OBJECTIVES Although there is concern that occupational exposures in some nursing professions may confer reproductive risks, there are few relevant studies. Our objective is to determine if a cohort of female registered nurses (RN) from British Columbia (BC), in comparison to BC women in general, have elevated rates of congenital anomalies, stillbirths, low birth weight, or prematurity in their offspring. METHODS A cohort of RNs from BC was linked to Vital Statistics birth records and the BC Health Status Registry (HSR) between the years 1986 and 2000. The RN offspring cohort included 23,222 births. For each outcome, odds ratios (OR) with 95% confidence intervals (CI) were determined by comparing rates in the nurses' cohort with the rates in the general population standardized for the year of birth. RESULTS Apart from chromosomal anomalies, for each of the ICD-9 congenital anomaly categories there were fewer congenital anomalies than expected, resulting in an overall prevalence of congenital anomaly cases (with at least one anomaly) that was significantly lower in the RN cohort (1,567 observed vs. 1,846 expected; OR 0.84, 95% CI 0.78-0.90) in comparison to the general population. Low birth weight (1,138 observed vs. 1,260 expected; OR 0.90, 95% CI 0.83-0.98) was also significantly lower, while prevalence of prematurity and stillbirths were not significantly different than among the general population. CONCLUSION Offspring of RNs in BC had a lower prevalence of congenital anomalies and low birth weight compared to the rates found among the general population. Further studies are underway to determine if subpopulations within the RN cohort are at risk.