Abstract
Background: Previous studies indicate the effects of thyroid dysfunction on adverse obstetric outcomes and fetal neurodevelopment, of which the results on gestational anemia are controversial. Here, we evaluated the influence of thyroid dysfunction on gestational anemia via published epidemiological articles and a new prospective study conducted by our team, respectively.Methods: We searched studies on the PubMed, Embase, MEDLINE, and Cochrane databases as of November 2019, and conducted a prospective study in which participants underwent thyroid function and blood routine testing throughout pregnancy.Results: The meta-analysis showed that pregnancies with overt hypothyroidism [OH; odds ratio (OR) = 3.74, 95% confidence interval (CI): 1.95–7.15] or that were thyroid peroxidase antibody (TPOAb)-positive (OR = 1.97, 95%CI: 1.19–3.26) had increased anemia risk, but similar results were not found in pregnancies with subclinical hypothyroidism (SCH) and hyperthyroidism. In the prospective study from our new data, the hypothyroid group had significant reductions in hemoglobin (Hb) (P = 0.048) and increased anemia risk (OR = 6.384, 95%CI: 2.498–16.311) during the second half of pregnancy. From the first to second half of pregnancy, the longitudinal reductions in Hb, erythrocyte (RBC), and hematocrit (Hct) levels were significantly increased in hypothyroid group.Conclusions: Our meta-analysis indicates that untreated OH or TPOAb-positive pregnant women have increased risk of anemia. In addition, our new data showed that treated hypothyroidism is also a risk factor for anemia in the second half of pregnancy rather than in the first half. The results may guide strengthening of Hb monitoring in pregnancies with thyroid dysfunction.
Highlights
Thyroid dysfunction is a common endocrine disease during pregnancy, and consists of overt hypothyroidism (OH), subclinical hypothyroidism (SCH), overt hyperthyroidism (OHyper), and thyroid peroxidase antibody (TPOAb)-positive status
OH and Anemia Meta-analysis of the five studies that reported relevant data on the relationship between anemia and OH showed that the combined odds ratio (OR) of anemia for OH pregnant women was 3.74 (95%confidence interval (CI): 1.95–7.15, P = 0, I2 = 59.7%), indicating that OH is associated with gestational anemia
Subgroup meta-analysis indicated that untreated OH in pregnancy increased anemia risk (OR = 6.03, 95%CI: 3.85–9.43, P = 0, I2 = 0%), while treated OH in pregnancy was not associated with anemia (OR = 1.76, 95%CI: 0.59–5.21, P = 0.308, I2 = 49.5%)
Summary
Thyroid dysfunction is a common endocrine disease during pregnancy, and consists of overt hypothyroidism (OH), subclinical hypothyroidism (SCH), overt hyperthyroidism (OHyper), and thyroid peroxidase antibody (TPOAb)-positive status. The prevalence of gestational anemia increases with the progress of pregnancy [11]. Iron deficiency anemia (IDA) accounts for 75% of anemia during pregnancy [12]. A crosssectional study by Veltri et al [16] showed that iron deficiency (ID) is related to high prevalence of thyroid autoimmune disease (TAI), higher serum thyroid-stimulating hormone (TSH), and lower free thyroxine (FT4) levels during the first trimester of pregnancy. Previous studies indicate the effects of thyroid dysfunction on adverse obstetric outcomes and fetal neurodevelopment, of which the results on gestational anemia are controversial. We evaluated the influence of thyroid dysfunction on gestational anemia via published epidemiological articles and a new prospective study conducted by our team, respectively
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