Australian and New Zealand Journal of Obstetrics and Gynaecology 2009; 49: 400 – 403 DOI: 10.1111/j.1479-828X.2009.01019.x 400 © 2009 The Authors Journal compilation © 2009 The Royal Australian and New Zealand College of Obstetricians and Gynaecologists Blackwell Publishing Asia Original Article Mid-trimester amniotic fluid C-reactive protein, ferritin and lactate dehydrogenase concentrations and subsequent risk of spontaneous preterm labour Sedigheh BORNA, 1 Fatemeh MIRZAIE 2 and Alireza ABDOLLAHI 3 1 Department of Fetal–Maternal Medicine, Vali-e-Asr Hospital, Tehran University of Medical Sciences, Tehran, 2 Department of Obstetrics and Gynecology, Kerman University of Medical Sciences, Kerman, and 3 Department of Pathology, Vali-e-Asr Hospital, Tehran University of Medical Sciences, Tehran, Iran Background: Preterm delivery is a serious problem in obstetrics. A pre-existing inflammation in the first half of gestation has been proposed as a possible condition that leads to preterm delivery. Aim: Our aim was to compare C-reactive protein (CRP), ferritin and lactate dehydrogenase (LDH) concentrations in mid-trimester amniotic fluid of patients with preterm and term deliveries and to found out their predictive values for preterm delivery. Methods: The study was conducted on 90 pregnant women who underwent genetic amniocentesis between the 15th and the 20th weeks of gestation. The samples were carried immediately to the laboratory for cytogenetic and biochemical examination. Non-parametric tests and receiver-operating characteristic curve analysis were used for statistical purpose. Results: This study showed women with preterm delivery at < 37 weeks (n = 17) had a higher median of amniotic fluid LDH concentration than those women who delivered at term (n = 73) (P = 0.003). Amniotic fluid LDH concentration of > 120 IU/L had a sensitivity of 59% and a specificity of 81% in the prediction of spontaneous preterm delivery at < 37 weeks. Maternal serum alpha-fetoprotein levels were higher in patients delivered preterm compared with term deliveries (P = 0.036). Conclusion: Mid-trimester LDH is found to be quite effective in the prediction of preterm delivery. Pre-existing intrauterine inflammatory process early in gestation may be an important risk factor for preterm delivery. Key words: amniocentesis, laboratory, inflammation, prediction, sensitivity, specificity. Introduction Preterm delivery is a serious problem in obstetrics, accounting for 70% of perinatal mortality and almost half of long-term neurological morbidity. 1 The physiological mechanism that initiates preterm delivery has not been substantially identified. Placental ischaemia and acute inflammation are the most common two pathologies that have been implicated. 2 Compelling clinical and experimental evidence has demonstrated an association among intrauterine inflammation and preterm delivery. 3 C-reactive protein (CRP) is a sensitive marker of inflammation that remains stable in serum. 4 Elevated concentrations of CRP in peripheral circulation have been associated with the presence of intrauterine infection. 5,6 Recently, investigators have noted elevated fluid CRP concentrations among women with intrauterine infections as compared with controls. 7,8 One particularly interesting potential inflammatory marker is ferritin. Ferritin is an iron-containing protein synthesised by a variety of tissues, 9,10 while low ferritin levels is a sensitive indicator of iron deficiency, and high ferritin levels have been associated with a variety of acute phase reactions, including inflammatory conditions. 11 Several investigators have reported an association between elevated serum ferritin concentrations and preterm labour. 12 Lactate dehydrogenase (LDH) catalyses the reversible oxidations of lactate to pyruvate in the final step of the glycolytic pathway and are a marker of acute inflammation in body fluids. Amniotic fluid LDH levels as a rapid amniotic fluid marker of subclinical infection have been demonstrated to be elevated in patients with preterm delivery. 13 Our aim in this study was to determine if concentrations of amniotic fluid CRP, ferritin and LDH obtained during genetic amniocentesis could identify patients at risk for spontaneous preterm delivery. Methods Study design and setting This prospective study was conducted in 2007 during a period of nine months, involved 110 singleton pregnancies that underwent genetic amniocentesis between the 15th and 20th weeks. Research ethics approval was obtained before Correspondence: Assistant Professor Fatemeh Mirzaie, Department of Obstetrics and Gynecology, Afzalipour Hospital, Kerman, Iran 76116914111. Email: swt_f@yahoo.com Received 2 September 2008; accepted 10 April 2009.