This single-center, retrospective cohort study was conducted at the First People's Hospital of Chongqing Liangjiang New Area, from January 2019 to November 2021. Medical data were extracted from electronic maternal clinical records. The study was conducted according to the principles of the Declaration of Helsinki (edition 1975) and was approved by the hospital ethics committee (ID 20210023).
A total of 1013 laboring mothers were included in this study. The inclusion criteria of the research group were: 1. Age ≥ 18 years; 2. DNA gene screening showed that they carried α/β-thalassemia heterozygous gene. See the diagnostic criteria, for specific genotypes. The study consisted of 4 groups: 116 cases of α-thalassemia group (αTT), 162 cases of β-thalassemia group (βTT), 108 cases of thalassemia combined with iron deficiency anemia (TT&IDA) group, and 81 cases of pure iron deficiency anemia (IDA) group. The control group included pregnant women without thalassemia characteristics, iron deficiency, and anemia. The matching criteria were maternal age, parity, and gestational age at delivery. 546 cases were randomly selected according to the 1:1 ratio. Oral iron supplementation was routine condacted in all pregnant women during the perinatal period.
Exclusion criteria: 1. History of diabetes, hypertension or gestational diabetes, gestational hypertension; 2. History of blood donation or blood transfusion in the past 4 months; 3. Other acute or chronic hemolytic nephropathy; 4. Homozygous α/ β-thalassemia, α + β-thalassemia; 5. IVF; 6. Pregnant women with twins; 7. Any other clinical condition that may affect hematopoiesis and/or red blood cell turnover; 8. Chromosomal disorders and congenital malformations.
The diagnostic criteria of this study include: (1) Anemia during pregnancy: Hb in peripheral blood of pregnant women is less than 110g/L[11]. (2) IDA during pregnancy: SF < 20ug/L, Hb < 110g/L[12]. (3) Gestational diabetes mellitus (GDM) is based on the diagnostic criteria issued by WHO in 2013[13]. (4) Intrahepatic cholestasis of pregnancy: the critical value of serum total bile acid of 10 µmol/L[14]. (5) Thalassemia Trait: Thalassemia gene diagnosis confirmed static α-thalassemia, standard α-thalassemia and β-thalassemia minor. (6) Intrauterine Growth Restriction (IUGR), defined as fetal weight below the tenth percentile of mean weight for gestational age.
After reviewing maternal examination records, pregnancy and neonatal outcomes, the adverse maternal outcomes include gestational diabetes mellitus, gestational hypertension, intrahepatic cholestasis of pregnancy, hypothyroidism of pregnancy, preeclampsia, dystocia, premature rupture of membranes (PPROM < 37 weeks); Adverse neonatal outcomes include: intrauterine growth restriction, neonatal hyperbilirubinemia, neonatal pneumonia, acute intrauterine distress.
All blood measurements (blood routine, OGTT) were performed in the Laboratory Department of the First People's Hospital of Liangjiang New Area, Chongqing. Blood routine examination concludes all data before 12 weeks of pregnancy, hemoglobin (Hb), red blood cell count (RBC), hematocrit (HCT) are measured by hematology analyzer, mean corpuscular volume (MCV), mean corpuscular hemoglobin content (MCH), mean corpuscular hemoglobin Concentration (MCHC), red blood cell volume distribution width (RDW) were calculated automatically from Hb and RBC counts.
The statistical analysis was performed with the R 4.1.2 software (freeware distributed by the R development core team). Categorical variables were presented as frequencies and percentages, were compared among groups using the χ2 test or the fisher exact test. Continuous variables were presented as mean and standard deviations, were compared among groups using the F-test. Pairwise comparisons were also evaluated. The stepwise logistic regression model was used to explore the risk factors for adverse maternal outcomes. The Odds ratio and its 95% confidence interval were computed. The level of statistical significance was set up at 0.05 for all tests.