eISSN: 2377-4304 OGIJ

Obstetrics & Gynecology International Journal
Research Article
Volume 1 Issue 3 - 2014
Reference Intervals of Hematological Variables for Healthy Antepartum and Postpartum Women
Qingchun Deng, Li Deng, Cheng Chen, Shan Meng, Yinglian Pan and Qing Chang*
Department of Gynecology and Obstetrics, Third Military Medical University, China
Received:October 19, 2014 | Published: December 04, 2014
*Corresponding author: Chang Qing, Department of Obstetrics and Gynecology, Southwest Hospital, Third Military Medical University, Chongqing, 400038, China. Tel: +86-23-68765399; Fax: +86-23-68765399; Email: @
Citation: Deng Q, Deng L, Chen C, Meng S, Pan Y, et al. (2014) Reference Intervals of Hematological Variables for Healthy Antepartum and Postpartum Women.Obstet Gynecol Int J 1(3): 00016. DOI: 10.15406/ogij.2014.01.00016


Objective: To report the reference intervals for antepartum and postpartum hematological variables.
Material and methods: The series consists of 488 women with a normal pregnancy duration of ≧37 weeks and a normal delivery with a newborn weight >2500 g. Blood samples were obtained 24 hours before birth and 24 hours after birth. The following indicators were analyzed: white blood cell (WBC), red blood cell (RBC), hemoglobin (HB), hematocrit (HCT), platelet (PLT), and neutrophil (NE) counts. Reference values were calculated as the mean ±1. 96 ×SD.
Results: Compared with antepartum measurements, RBC, Hb, PLT, and HCT values declined at 24 hours postpartum (P < 0. 05), whereas WBC and NE values significantly increased (P < 0. 05).
Conclusion: The characteristic changes occurring in hematological indices at 24 h antepartum and 24 h postpartum are described in this study. The results may be used as reference values in the assessment of blood infection in antepartum and postpartum women.
Keywords: Normal Pregnancy Women; Hematological Variables; Reference Intervals


Hematological variables change significantly as a pregnancy progresses. Similarly, hematological variables also change significantly 24 h after birth. These changes are partly attributed to blood dilution, nutrition intake during the periods of pregnancy, and bleeding in the process of delivery [1,2]. A thorough understanding of the hematological changes can serve as a guide for disease diagnosis and the rational use of drug postpartum. To date, the reference intervals for antepartum and postpartum hematological variables have not been fully investigated. Here, we describe the hematological variables 24 h before birth and after birth in this study and then analyze the reference intervals for hematological variables to provide favorable standards for antepartum and postpartum disease diagnosis.

Materials and Methods

For this study, 488 women patients were randomly selected from the Department of Gynecology at the Southwest Hospital from August 2011 to December 2012. All participants fulfilled following inclusion criteria: healthy, 21 to 35 years old, weighs between 48 to 76 kilograms, experiencing a normal pregnancy, spontaneous delivery, no postpartum hemorrhage determined, no antibiotic use 2 weeks before delivery, normal temperature before labor, no other diseases, and no serious pregnancy complications and labor complication. Every woman selected for this study provided informed voluntarily consent and completed the questionnaires.
All selected women completed routine blood work 24 h before birth and 24 h after birth. We analyzed hematological variables, including WBC, RBC, HB, PLT, NE, and HCT, and explored reference intervals. Blood samples were collected in a routine method. Venipuncture was performed in an antecubital vein. The blood samples were collected in BD purple cap vacuum tubes (2 ml, EDTA-k2 anticoagulation). Blood samples were analyzed by an automated cell counter (Sysmex XE-2100, Japan) and reagents (Sysmex, Japan).
Statistical analysis was performed using SPSS 13.0 statistical software (SPSS, Chicago, IL, USA). For single samples, data were assessed using the Kolmogorov-Smirnov test. The normal distributions of the hematological values were evaluated by histograms. Reference intervals were calculated as the mean ± 1.96 × SD [3]. Paired antepartum and postpartum hematological variables were assessed using a paired t-test.


Clinical characteristics
A total of 488 patients met the inclusion criteria. All patients experienced a full-term pregnancy and vaginal delivery. In total, 168 (34.4%) patients were administered epidural analgesia, and 189 (38.7%) women experienced an episiotomy. The mean volume of postpartum hemorrhage in two hours was 215.4 ml, and postpartum hemorrhage was not noted in any patient. In total, 39 (7.8%) patients experienced a fever greater than 37.3°C. The clinical characteristics of all women are presented in Table 1.
The reference intervals of hematological variables
We established normal reference intervals for antepartum and postpartum hematological variables in healthy women (Table 2). The WBC, RBC, HB, PLT, NE, and HCT reference intervals in non-pregnant women are 4×109~10×109/L, 3.5×1012~5.0×1012/L, 110~150 g/L, 100~300×109/L, 50~70%, and 37~48%, respectively. However, our antepartum reference interval results for WBC, RBC, HB, PLT, NE, and HCT are 3.42×109~15.69×109/L, 3.168.93~251.77×109/L, 93.86~146.25 g/L, 59.8~286.2×109/L, 4.84~18.14×109/L (70.81~90.73%), and 24.56~47~4.61×1012/L, respectively. These respective postpartum values are 7.06~21.16×109/L, 2.72~4.39×1012/L, 79.49~137.89 g/L, 0.81%, 4.84~18.14×109/L (70.81~90.73%), and 24.56~47~4.61×1012/L. These lower and upper reference limits significantly differ among non-pregnant, antepartum, and postpartum women.


Anemia is the most common hematological problem in the process of pregnancy. From this study, we also found changes of the hematological variables for antepartum and postpartum women. Therefore, for antepartum and postpartum women, there will be a mistake to classify normal and abnormal according to no-pregnant women’ reference values [4,5]. Better understanding the reference interval of hematological variables is essential for disease diagnosing and treatment in antepartum and postpartum women.
Here, we demonstrated that physiologic anemia is typically observed in normal antepartum and postpartum women due to blood dilution. In fact, this outcome does not seriously affect pregnancy outcome [6]. During the period of a normal pregnancy, plasma volumes red blood cells gradually increase. Physiologic anemia occurs when the plasma volume increases more rapidly than the increase in red blood cells occurs [7,8]. Intervention behaviors increased during the process of delivery along with advancing perinatology. For example, the administration of prophylactic antibiotics to women who undergo vaginal delivery not only enhance economic burden but also influence postpartum breast feeding. In a normal pregnancy, our results indicate that white cell counts increase in antepartum and postpartum women. The mechanism of increased white cell counts has not been clearly investigated. A complicated physiological procedure results in increased white cell counts during the gestational period. A series of changes occurs in the genital system, endocrine system, and metabolic processes during gestation. Therefore, white cells obviously increase because white cells accept a series of stimulatory signals as gestation progresses [9]. The previous studies indicate that the increase in white cells during gestation is associated with the release of leukocytes from marginal pools [10]. Thus, it is unreasonable to use antibiotics to prevent infection during birth. Our data indicate that the white cell counts were more significantly increased in postpartum women compared with antepartum women, whereas CRP and temperature generally remained at normal levels. These changes are possibly attributed to physiological fluctuations and reflect enhanced immune functions.


N=488, value*

Maternal age (years)


Maternal BMI (kg/m2)


Gestational age (days)



168 (34.4%)


189 (38.7%)

Volume of postpartum hemorrhage in two hours (ml)

215.4 (42.6)


39 (7.8%)


46 (9.4%)

Birth weight (grams)


Birth height (cm)


Apgar scores


Table 1: Characteristics of all vaginal deliveries during the study period. BMI: Body Mass Index; CRP: C-Response Protein *Mean ± SD or N (%)



37-40 weeks (n=488)

24 h after postpartum (n=488)




95% CI*



WBC (×109/L)







RBC (×1012/L)







HB (g/L)







PLT (×1012/L)







NE (%)







NE# (×109/L)







HCT (%)







Table 2: Mean and 95% confidence intervals for Hematological Variables in healthy antepartum and postpartum women. *95% CI= x̄±1.96s

In conclusion, we presented updated reference intervals for various hematological variables in healthy pregnant women at 24 hours before and after birth. Our results potentially provide novel reference levels for the diagnosis and treatment of diseases in antepartum and postpartum women.


  1. Robeck TR, Nollens HH (2013) Hematological and serum biochemical analytes reflect physiological challenges during gestation and lactation in killer whales (orcinus orca). Zoo Biol 32(5): 497-509.
  2. Sharma SK, Philip J, Wiley J (1997) Thromboelastographic changes in healthy parturients and postpartum women. Anesth Analg 85(1): 94-98.
  3. Katayev A (2010) Estimating reference intervals. Am J Clin Pathol 134(2): 351.
  4. Townsley DM (2013) Hematologic complications of pregnancy. Semin Hematol 50(3): 222-231.
  5. Chang YH, Yang SH, Wang TF, Lin TY, Yang KL, et al. (2011) Complete blood count reference values of cord blood in Taiwan and the influence of gender and delivery route on them. Pediatr Neonatol 52(3): 155-160.
  6. Shields RC, Caric V, Hair M, Jones O, Wark L, et al. (2011) Pregnancy-specific reference ranges for haematological variables in a Scottish population. J Obstet Gynaecol 31(4): 286-289.
  7. Scholl TO, Reilly T (2000) Anemia, iron and pregnancy outcome. J Nutr 130 (2S Suppl): 443S-447S.
  8. Milman N, Bergholt T, Byg KE, Eriksen L, Hvas AM (2007) Reference intervals for haematological variables during normal pregnancy and postpartum in 434 healthy danish women. Eur J Haematol 79(1): 39-46.
  9. Solves P, Lopez M, Mirabet V, Blanquer A, Roig R, et al. (2009) Characteristics of umbilical cord blood units collected from preterm deliveries. Gynecol Obstet Invest 68(3): 181-185.
  10. Marin GH, Fazio P, Rubbo S, Baistrocchi A, Sager G, et al. (2002) [Prevalence of anaemia in pregnancy and analysis of the underlying factors]. Aten Primaria 29(3): 158-163.
© 2014-2019 MedCrave Group, All rights reserved. No part of this content may be reproduced or transmitted in any form or by any means as per the standard guidelines of fair use.
Creative Commons License Open Access by MedCrave Group is licensed under a Creative Commons Attribution 4.0 International License.
Based on a work at https://medcraveonline.com
Best viewed in Mozilla Firefox | Google Chrome | Above IE 7.0 version | Opera |Privacy Policy