Maternal anemia and long-term respiratory morbidity of the offspring --
Results of a population-based cohort
Abstract
Objective: To evaluate the association between prenatal maternal anemia
(hemoglobin, Hb<11 g/dl) and long-term respiratory morbidity
of the offspring. Methods: A retrospective population-based cohort
analysis was performed at the Soroka University Medical Center (SUMC), a
single regional tertiary medical center. All singletons born between the
years 1991-2014 and discharged alive were included in the study.
Offspring with congenital malformations were excluded. The three study
groups were defined based on maternal Hb levels, measured upon
postpartum discharge: <7.0 (severe anemia), 7.0-11.0 (mild to
moderate anemia), and ≥11.0 g/dl (unexposed). Respiratory morbidity
diagnosis was based on predefined ICD-9 codes of lung disease
definitions, based on the medical records of the hospitalized offspring
in SUMC. A Kaplan-Meier survival curve was formed to compare the
cumulative respiratory morbidity during the study follow-up period
between the study groups, and a multivariable Cox survival analysis was
used to control for cofounders. Results: During the study period,
214,305 deliveries met the inclusion criteria. Of those, 807 (0.3%)
mothers had severe anemia, 105,196 (49.1%) mothers had mild-moderate
anemia, and the remaining were not anemic (108,302, 50.5%). Respiratory
hospitalization incidence was found to be significantly higher among the
offspring born to anemic mothers (6.2%; 5.3% and 5.1%; p = 0.020, p
for trend=0.007 in severe, mild-to-moderate and non-anemic mothers,
respectively). The association between maternal anemia and
respiratory-related hospitalization of the offspring remained
significant among the mild-moderate anemic group after adjusting for
confounders in the Cox proportional hazards model (adjusted hazard
ratio=1.1; 95% CI 1.05-1.14; p < 0.01). As to the association
between severe maternal anemia and offspring morbidity no significant
differences were found (p= 0.133), although a linear hazard
dose-response ratio was found between the mild-moderate and severe
anemic groups (aHR=1.09, aHR 1.24, respectively). Conclusion: Maternal
anemia was found to be associated with long-term respiratory morbidity
of the offspring.