Bailit Jennifer L, Doty Elizabeth, Todia William
Division of Maternal-Fetal Medicine, Center for Health Care Research and Policy, and Department of Obstetrics and Gynecology, MetroHealth Medical Center, Case Western Reserve University, Cleveland, Ohio 44109-1998, USA.
J Reprod Med. 2007 Jul;52(7):619-22.
To determine the incidence of anemia in the third trimester among women with normal hematocrits early in pregnancy.
Low-risk women seeking prenatal care were identified. Patients with a hematocrit >33% in the first or second trimester and a hematocrit drawn in the third trimester were included. Rates of anemia; hematocrit <33%; and severe anemia, hematocrit < 30%; were determined. The primary outcome was the development of anemia in the third trimester.
A total of 1,604 women met inclusion criteria; 16.2% of women became anemic, and 4.5% became severely anemic in the third trimester. Using a starting hematocrit value of 39% as a cutoff, only 66% of women would need to be rescreened in the third trimester in order to detect 78.5% of anemias (sensitivity 78.5%, specificity 39.7%, negative predictive value 90.5%).
The percent of women with normal hematocrits in the first trimester who become anemic in the third trimester is 16.2. Hematocrit screening in the third trimester may be unnecessary for low-risk women with starting hematocrits > 39%.
确定妊娠早期血细胞比容正常的女性在孕晚期贫血的发生率。
确定寻求产前护理的低风险女性。纳入在孕早期或孕中期血细胞比容>33%且在孕晚期进行血细胞比容检测的患者。确定贫血发生率（血细胞比容<33%）以及严重贫血发生率（血细胞比容<30%）。主要结局是孕晚期发生贫血。
共有1604名女性符合纳入标准；16.2%的女性在孕晚期发生贫血，4.5%的女性发生严重贫血。以起始血细胞比容值39%作为临界值，在孕晚期仅需对66%的女性进行重新筛查，就能检测出78.5%的贫血病例（敏感性78.5%，特异性39.7%，阴性预测值90.5%）。
孕早期血细胞比容正常的女性在孕晚期发生贫血的比例为16.2%。对于起始血细胞比容>39%的低风险女性，孕晚期进行血细胞比容筛查可能没有必要。
