Journal of Infertility and Reproductive Biology, 2013, Volume 1, Issue 2, Pages: 37-42 37 Association between Maternal Serum Inhibin A and Chromosomal Abnormalities as a Diagnostic Markers in First Trimester of Threatened Abortion Mohamed Gamal 1 , Neveen A. Ashaat 2 , Sayed Bakry 1 , Ahmed Abdullah 3 , Mohamed Farahat 4 , Zaki T. Zaki 1 1. Zoology Department, school of Scienc, Al Azhar University, Cairo, 11884, Egypt. 2. Zoology Department, Faculty of Women for Arts, Science & Education, Ain Shams University, Cairo, Egypt. 3. Biochemistry Department, school of Pharmacy, Al Azhar University, Cairo, Egypt. 4. Obstetrics & Gynecology Department, School of Medicine, Al Azhar University, Cairo, Egypt. Abstract Background: Threatened abortion is defined as a pregnancy complicated by bleeding before 20 weeks’ gestation. Objective: Assessment of the relation between the concentration of serum Inhibin A and chromosomal abnormalities in a trial to find marker for the threatened abortion. Patients and Methods: The present study included 40 pregnant women in the first-trimester, 20 pregnant women suffering from pregnancy complications (threatened aborted) and 20 pregnant women for control. Blood samples were collected from El Hussain Hospital, Cairo, Egypt, under the clinical supervision. Serum is prepared for measurement Inhibin A hormone using Enzyme- Linked Immuno-Sorbent Assay (ELISA), while heparinized blood processed for cell culture to determine chromosomal aberrations. Results: Cytogenetic analysis revealed that structural chromosomal abnormalities were recorded in 35 from 600 maternal metaphase (5.83%), compared to (2.6%) that were detected in the examined metaphases of control group; there was no statistical significance between the control and threatened aborted cases (χ² = 0.85, P ˃ 0.05), while concentration of Inhibin A hormone in the studied group shows Mean of 16.7 pg/ml but in control group shows concentration of 38.7 pg/ml, there was a significant difference between the two groups in serum level of inhibin A (t = 12.9, P < 0.05). On the other hand we found no correlation between chromosomal anomalies and inhibin A level in our cases (r = -0.296, p=0.204). Conclusion: Serum inhibin A measured during the first trimester of pregnancy might be useful for prediction of threatened abortion. Key word: Threatened abortion, Inhibin A, chromosomal abnormalities. Introduction Threatened abortion is a condition in which vaginal bleeding is less than in inevitable abortion and the cervix is not dilated, and abortion may or may not occur, (1). First-trimester vaginal bleeding is one of the most common complications in pregnancy with an incidence of 15–25%. About half of these will end in miscarriage within 20 weeks of gestation (2,3) and those women who remain pregnant have an increased risk of developing other complications later in pregnancy (4). Maternal age is an independent risk * Corresponding Address: Zoology Department, school of Science, Al Azhar University, Cairo, 11884, Egypt, Email: Mohamed86gamal@yahoo.com factor for threatened miscarriage. Women between the ages of 25 and 30 years had the lowest risk of spontaneous abortion, whereas those with the highest risk of spontaneous abortion were at the extremes of age. It was found that a chromosomal abnormality occurs in 49 percent of spontaneous abortions (5). On the other hand inhibins are glycoproteins produced by the granolosa and theca cells of the ovary and by the Sertoli cells of the testis. Inhibin is a dimeric disulfide-linked glycoprotein molecule, consisting of α and subunits β (6). All inhibins share a common subunit (18–20 kDa), but depending on the type of subunit [A (13 kDa) and B (15 kDa)], inhibin is classified as inhibin A or B. Apart from inhibin A or B, these subunits are also present in circulation in