Proposed screening criteria for beta-thalassemia trait during early pregnancy in southern China.

This study was carried out to evaluate whether it is effective to use mean corpuscular volume (MCV) <80 fL as a screening test in the first step of screening for beta-thalassemia (beta-thal) trait in southern China. The data of hematological testing in the first or early second trimester of gestation of 449 pregnant women who underwent prenatal diagnosis for beta-thal were retrospectively reviewed. Of these, six (1.3%) had an MCV value >80 fL, ranging from 80.3 to 83.4 fL. This meant that six at-risk pregnancies would have been missed if only an MCV cut-off value of <80 fL had been used for screening. All subjects having a normal MCV value carried the same -28 (A>G) mutation, accounting for 9.8% (6/61) of the total number of mother with this mutation. If screening had been based on the mean corpuscular hemoglobin (MCH) <27 pg, all 449 pregnant women with beta-thal trait would have been detected. We suggest that all pregnant women presenting at an antenatal clinic with an MCH of <27 pg rather than an MCV of <80 fL should be investigated further to confirm or exclude a diagnosis of beta-thal trait in our region.