Maternal Anemia and Small for Gestational Age at Birth: Retrospective Delivery Cohort

Location

Center for Advanced Learning & Simulation (CALS)

Publication Date

May 2026

Start Date

8-5-2026 9:15 AM

End Date

8-5-2026 9:30 AM

Description

Introduction: The World Health Organization estimates that 37% of pregnant women worldwide are affected by anemia. In pregnancy, anemia is defined as a hemoglobin <11 g/dL in the first and/or third trimesters and <10.5 g/dL in the second trimester. Previous studies have reported that moderate to severe maternal anemia appears to have an association with fetal growth, specifically with diagnoses of fetal growth restriction in utero and small for gestational age (SGA) at birth. The aim of our study was to evaluate the prevalence of SGA in pregnant patients diagnosed with and without anemia during pregnancy. We hypothesized that pregnant patients diagnosed with anemia will have higher prevalence of SGA than those without anemia diagnosis.

Methods: We performed a retrospective cohort analysis of 2,016 deliveries from 2018 to 2021. Admission anemia was defined by either hemoglobin <11 g/dL and/or hematocrit <33% measured at admission for hospital delivery. Small for gestational age (SGA) was defined by birthweight for gestational age percentile <10th. Crude associations were assessed with chi-square testing. Multivariable models adjusted for age, initial BMI, and race collapsed as Black vs Other/Unknown. A secondary analysis examined first-trimester anemia among records with non-missing initial anemia status.

Results: Overall, anemia at delivery admission was present in 989 of 2,016 patients (49.1%), and 291 of 2,016 infants born (14.4%) were considered SGA. The prevalence of SGA was 12.9% among patients with admission anemia versus 15.9% among those without admission anemia (p=0.071). The crude odds ratio for SGA with admission anemia was 0.79 (95% CI 0.61-1.01). After adjustment for maternal age and BMI, admission anemia was associated with lower odds of SGA (aOR 0.71, 95% CI 0.55–0.91; p=0.007). In the subset with first-trimester anemia data (n=1,789), initial anemia was not associated with SGA without and with adjustment (OR 1.05, 95% CI 0.77-1.44; aOR 1.01, 95% CI 0.74–1.38; p=0.95 respectively).

Conclusions: Admission anemia was not associated with a higher prevalence of SGA; the adjusted analysis showed a modest inverse association, while first-trimester anemia was not associated with SGA. These findings do not support the original hypothesis and suggest that anemia measured at delivery may not capture the antepartum exposure window most relevant to fetal growth.

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Advisor: Tabitha Quebedeaux MD/PhD

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May 8th, 9:15 AM May 8th, 9:30 AM

Maternal Anemia and Small for Gestational Age at Birth: Retrospective Delivery Cohort

Center for Advanced Learning & Simulation (CALS)

Introduction: The World Health Organization estimates that 37% of pregnant women worldwide are affected by anemia. In pregnancy, anemia is defined as a hemoglobin <11 g>/dL in the first and/or third trimesters and <10.5 g/dL in the second trimester. Previous studies have reported that moderate to severe maternal anemia appears to have an association with fetal growth, specifically with diagnoses of fetal growth restriction in utero and small for gestational age (SGA) at birth. The aim of our study was to evaluate the prevalence of SGA in pregnant patients diagnosed with and without anemia during pregnancy. We hypothesized that pregnant patients diagnosed with anemia will have higher prevalence of SGA than those without anemia diagnosis.

Methods: We performed a retrospective cohort analysis of 2,016 deliveries from 2018 to 2021. Admission anemia was defined by either hemoglobin <11 g>/dL and/or hematocrit <33% measured at admission for hospital delivery. Small for gestational age (SGA) was defined by birthweight for gestational age percentile <10th. Crude associations were assessed with chi-square testing. Multivariable models adjusted for age, initial BMI, and race collapsed as Black vs Other/Unknown. A secondary analysis examined first-trimester anemia among records with non-missing initial anemia status.

Results: Overall, anemia at delivery admission was present in 989 of 2,016 patients (49.1%), and 291 of 2,016 infants born (14.4%) were considered SGA. The prevalence of SGA was 12.9% among patients with admission anemia versus 15.9% among those without admission anemia (p=0.071). The crude odds ratio for SGA with admission anemia was 0.79 (95% CI 0.61-1.01). After adjustment for maternal age and BMI, admission anemia was associated with lower odds of SGA (aOR 0.71, 95% CI 0.55–0.91; p=0.007). In the subset with first-trimester anemia data (n=1,789), initial anemia was not associated with SGA without and with adjustment (OR 1.05, 95% CI 0.77-1.44; aOR 1.01, 95% CI 0.74–1.38; p=0.95 respectively).

Conclusions: Admission anemia was not associated with a higher prevalence of SGA; the adjusted analysis showed a modest inverse association, while first-trimester anemia was not associated with SGA. These findings do not support the original hypothesis and suggest that anemia measured at delivery may not capture the antepartum exposure window most relevant to fetal growth.