To determine the reference intervals of A1C in healthy pregnant women from urban area of Karachi, Pakistan
DOI:
https://doi.org/10.55629/pakjpathol.v37i1.961Abstract
Objective: To determine the reference interval of A1C in healthy pregnant women from urban areas of Karachi, Pakistan.
Material and Methods: This cross-sectional study was conducted at Hamdard university hospital, Taj medical complex, from 1st July to 31st December 2024. The study was a cross-sectional study involving healthy pregnant women (18-45 years) with normal 75g oral glucose tolerance test (OGTT). Women with diabetes, hypertension, hemoglobin <10 g/dl, comorbidities, and infections were excluded. On the basis of informed consent, demographic and clinical data were obtained. A1C was measured in venous samples by Turbidimetric inhibition immunoassay (Roche© c-311) with close calibration and exclusion of compromised samples to assure accuracy.
Results: Mean HbA1c was highest in the second trimester (4.14±0.79%) with a slight rise in the third (4.33±0.78%), reflecting expected physiological trends. Reference ranges were 2.7–5.7% (second trimester) and 2.8–5.5% (third), showing minor variation from global data. These findings highlight gestational variation in HbA1c and support the use of locally defined trimester-specific ranges for accurate interpretation in South Asian populations.
Conclusions: Trimester wise HbA1c reference values in healthy pregnant women are more effective to measure glycaemic control compared with generic non-pregnant reference ranges. An HbA1c of >5.6% can suggest a higher risk of gestational diabetes mellitus and should be followed by additional testing which is the gold standard oral glucose tolerance test (OGTT).
Keywords: Anemia, Gestational diabetes, Iron-deficiency, Pregnant women
References
Yuen L, Hannah W, Hare M, Simmons D. Hyperglycaemia in pregnancy: the role of ethnicity and geography in risk and outcomes. Diabetologia. 2025; 68 (11); 2340-61. DOI: https://doi.org/10.1007/s00125-025-06510-7
Olmos-Ortiz A, Flores-Espinosa P, Díaz L, Velázquez P, Ramírez-Isarraraz C, Zaga-Clavellina V. Immunoendocrine dysregulation during gestational diabetes mellitus: The central role of the placenta. Int J Mol Sci. 2021; 22(15): 8087. DOI: https://doi.org/10.3390/ijms22158087
Abbas S, Khattak M, Hameed S, Saeed S, Shabir R. HbA1c as an early diagnostic marker in gestational diabetes mellitus. Professional Med J. 2024; 31(05): 750-6. DOI:https://doi.org/10.29309/TPMJ/2024.31.05.7993
Beunen K, Neys A, Van Crombrugge P, Moyson C, Verhaeghe J, Vandeginste S, et al. Fasting plasma glucose level to guide the need for an OGTT to screen for gestational diabetes mellitus. Acta Diabetol. 2022; 59(3): 381-94. DOI: https://doi.org/10.1007/s00592-021-01812-9
Bogdanet D, O’Shea P, Lyons C, Shafat A, Dunne F. The oral glucose tolerance test—is it time for a change? —a literature review with an emphasis on pregnancy. J Clin Med. 2020; 9(11): 3451. DOI: https://doi.org/10.3390/jcm9113451
Silke O, Yim IS, Shaikh K, Lalani S, Ghani F, Wanyonyi S, et al. Is HbA1c associated with birth weight? A multivariable analysis of Pakistani pregnant women. J Obstet Gynaecol Res. 2023; 49(8): 2048-55. DOI: https://doi.org/10.1111/jog.15706
Obeagu GU, Altraide BO, Obeagu EI. Iron deficiency anemia in pregnancy and related complications with specific insight in Rivers State, Nigeria: A narrative review. Ann Med Surg. 2025; 87(6): 3435-44. DOI: https://doi.org/10.1097/ms9. 0000000000003224
Punnose J, Malhotra RK, Sukhija K, Rijhwani RM, Sharma A, Choudhary N, et al. Establishing trimester-specific haemoglobin A1c reference intervals in pregnant women: a retrospective study of healthy south Asian women with normal pregnancy outcomes. Sultan Qaboos Univ Med J. 2023; 23(1): 81-9. DOI: https://doi.org/10.18295/squmj.3.2022.022
Cavagnolli G, Pimentel AL, Freitas PA, Gross JL, Camargo JL. Effect of ethnicity on HbA1c levels in individuals without diabetes: Systematic review and meta-analysis. PloS One. 2017; 12(2): e0171315. DOI: https://doi.org/10.1371/journal.pone.0171315
Chigusa Y, Ikeda Y, Yamamura A, Mogami H, Nishimura A, Morita S, et al. Role of random blood glucose and HbA1c levels in optimizing glucose tolerance screening in early pregnancy: A retrospective cohort study. Obstet Gynecol Sci. 2025; 68(4): 273-82. DOI: https://doi.org/10.5468/ogs.25052
Nisa KU, Taj A, Dahri B, Sajida S, Hashmi H, Wahid N. The frequency of gestational diabetes mellitus & its responsible factors among pregnant women presenting at a tertiary care hospital, Karachi. Int J Health Sci. 2023; 7(S1): 386-94. DOI: https://doi.org/10.53730/ijhs.v7nS1.14211
O’Connor C, O’Shea PM, Owens LA, Carmody L, Avalos G, Nestor L, et al. Trimester-specific reference intervals for haemoglobin A1c (HbA1c) in pregnancy. Clin Chem Lab Med. 2012; 50(5): 905-9. DOI: https://doi.org/10.1515/cclm.2011.397
Deng Y, Cheng D, Liao G, Tan X, Yang J. Trimester-specific reference intervals for hemoglobin A1c in non-diabetic pregnancy in a Chinese population. BMC Pregnancy Childbirth. 2023; 23(1): 671. DOI: https://doi.org/10.1186/s12884-023-05980-0
Hiramatsu Y, Shimizu I, Omori Y, Nakabayashi M. Determination of reference intervals of glycated albumin and hemoglobin A1c in healthy pregnant Japanese women and analysis of their time courses and influencing factors during pregnancy. Endocr J. 2012; 59(2): 145-51. DOI: https://doi.org/10.1507/endocrj.K10E-410
Mosca A, Paleari R, Dalfra MG, Di Cianni G, Cuccuru I, Pellegrini G, et al. Reference intervals for hemoglobin A1c in pregnant women: Data from an Italian multicenter study. Clin Chem. 2006; 52(6): 1138-43. DOI: https://doi.org/10.1373/clinchem.2005.064899
Sánchez-González CM, Castillo-Mora A, Alvarado-Maldonado IN, Ortega-González C, Martínez-Cruz N, Arce-Sánchez L, et al. Reference intervals for hemoglobin A1c (HbA1c) in healthy Mexican pregnant women: A cross-sectional study. BMC Pregnancy Childbirth. 2018; 18(1): 424. DOI: https://doi.org/10.1186/s12884-018-2057-x
Khan A, Asif N, Ullah R, Khan TA, Khan A, Malik SS. Establishing reference intervals for HBA1C in all three trimesters of pregnancy; A Cross-sectional study on healthy pregnant women of Quetta, Baluchistan. Pak Armed Forces Med J. 2023; 73(1): 84. DOI: https://doi.org/10.51253/pafmj.v73i1.4814
Versantvoort AR, Van Roosmalen J, Radder JK. Course of HbA1c in non-diabetic pregnancy related to birth weight. Neth J Med. 2013; 71(1): 22-5. Available from: https://www.njmonline.nl/ getpdf.php?id=1258
Lowe Jr WL, Scholtens DM, Kuang A, Linder B, Lawrence JM, Lebenthal Y, et al. Hyperglycemia and adverse pregnancy outcome follow-up study (HAPO FUS): maternal gestational diabetes mellitus and childhood glucose metabolism. Diabetes Care. 2019; 42(3): 372-80. DOI: https://doi.org/10.2337/dc18-1646
Renz PB, Cavagnolli G, Weinert LS, Silveiro SP, Camargo JL. HbA1c test as a tool in the diagnosis of gestational diabetes mellitus. PloS One. 2015; 10(8): e0135989. DOI: https://doi.org/10.1371/journal.pone.0135989
Mostafa SA, Davies MJ, Webb DR, Srinivasan BT, Gray LJ, Khunti K. Independent effect of ethnicity on glycemia in South Asians and white Europeans. Diabetes Care. 2012; 35(8): 1746-8. DOI: https://doi.org/10.2337/dc11-2079
Metcalf P, Kyle C, Kenealy TW, Sundborn G, Jackson RT. Ethnic differences in HbA1c in adults in New Zealand: A cross-sectional study. Integr Obesity Diabetes. 2018; 4(2): 1-7. DOI: https://doi.org/10.15761/IOD.1000205
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