Iron deficiency anemia, cigarette smoking and risk of abruptio placentae

A higher frequency of abruptio placentae among anemic patients has been documented in some, but not all previously published studies. Altered feto-placental angiogenesis during early pregnancy in anemic women may partially explain this increased risk. The present study assesses the iron deficiency anemia-abruptio placentae association in pregnant women from the Pacific Northwest.

A retrospective case-control study of 145 abruptio placentae cases and 1710 control subjects was conducted. The diagnosis of abruptio placentae was based on routine clinical examination performed by attending physicians. Iron deficiency anemia was assessed in early pregnancy and defined as hemoglobin level <10 g/dL or by physician diagnosis. Information on maternal sociodemographic characteristics, cigarette smoking status during pregnancy and reproductive history was abstracted from medical records. Logistic regression was used to estimate odds ratios (OR) and 95% confidence intervals (CI) after adjusting for confounders.

Eleven percent of abruptio placentae cases and 3.3% of controls were diagnosed with iron deficiency anemia. Maternal iron deficiency anemia in early pregnancy was associated with a 3.60-fold increased risk of abruptio placentae (95% CI 2.01-6.04). After adjusting for maternal age, gravidity, smoking during pregnancy, Medicaid payment status, and pre-gestational hypertension, the association was attenuated but remained statistically significant (adjusted OR = 2.40; 95% CI 1.22-4.73). Maternal smoking during pregnancy was associated with a 2.40-fold increased risk of abruptio placentae (95% CI 1.19-3.52). The iron deficiency anemia-abruptio placentae association was not modified by maternal smoking.

Our results support the hypothesis that maternal iron deficiency anemia is associated with an increased risk of abruptio placentae.