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Wheeler, Transmission-line properties of a strip on a dielectric sheet on a plane, IEEE Trans Microwave Theory Tech 25 (1977), 631– 647. © 2007 Wiley Periodicals, Inc. DETERMINATION OF PREGNANCY USING MICROWAVES Anil Lonappan, 1 C. Rajasekaran, 2 Vinu Thomas, 1 G. Bindu, 1 and K. T. Mathew 1 1 Department of Electronics, Microwave Tomography and Materials Research Laboratory, Cochin University of Science and Technology, Kochi 682 022, India 2 Department of Medicine, Medical College, Trivandrum 695 011, India Received 17 August 2006 ABSTRACT: In today’s life, microwave technology is used in both di- agnostic and therapeutic procedure. This letter presents the study of dielectric properties of pregnant women urine as well normal women urine at microwave frequencies. In vitro measurements using cavity per- turbation technique is employed in the frequency range between 2 and 3 GHz. It is observed that dielectric constant of pregnant women urine samples is smaller than the normal women urine samples and the con- ductivity of pregnant women urine samples is higher than that of normal women urine samples, which is a novel alternative in vitro method of determining pregnancy, and is required for a woman to make prepara- tions for proper prenatal care and family planning. The same samples are subjected to investigations in the clinical laboratory for quantitative analysis, which holds good for our microwave study. © 2007 Wiley Pe- riodicals, Inc. Microwave Opt Technol Lett 49: 786 –788, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22279 Key words: pregnancy; urine; cavity perturbation; quantitative analy- sis; family planning 1. INTRODUCTION Every woman will experience her own unique physical indication of pregnancy such as nausea—particularly in the morning, vom- iting, fatigue, sleeplessness, tenderness in the breasts, and frequent urination. Human chorionic gonadotropin (hCG) pregnancy tests determine pregnancy through the detection of the hormone hCG in a woman’s urine. hCG is a glycoprotein hormone secreted by the developing placenta shortly after a fertilized egg has implanted in the uterine lining. The appearance of hCG soon after conception— and its subsequent rise in concentration during early gestational growth—make it an excellent marker for the early detection of pregnancy. Pregnancy tests come in two common formats—test strips and midstream tests. This requires the use first morning urine, as this urine sample contains the most concentrated amount of hCG and if it is not feasible, urination is avoided for several hours before using a pregnancy test. Pregnancy test strip is used in a clean dry container with urine and holding the test strip in the container for several seconds, while in midstream tests, simply holding the test in the stream of urine. Even though both test formats are equally reliable, the reaction time of the test is 5 min and generally, at 3–5 min. In some cases, a positive result will show up quickly if the hCG level is high in the urine, but for most of the tests, it requires a minimum 5-min interval to verify a negative result for pregnancy. It is important that a woman be tested as soon as she suspects that she may be pregnant in order that she can make preparations for proper prenatal care and family planning. Microwave nowadays plays important contributions to both diagnostic and therapeutic medicine and a lot of microwave med- ical devices were developed for biomedical applications and used in practice [1]. Dielectric parameters of various human tissues at different RF frequencies were reported by Gabriel et al. [2, 3], Cook [4], and Land and Campbell [5], while human blood studied at microwave frequencies using coaxial line and wave-guide method has been reported by Cook [6]. Studies on the variation of dielectric properties of body fluids and calcifications at microwave frequencies have revealed that diagnosis is possible through this method [7, 8]. This communication reports dielectrical properties of pregnant women urine as well normal women urine at microwave frequen- cies and the obtained results indicate that dielectric constant of pregnant women urine samples is smaller than the normal woman urine samples and the conductivity of pregnant women urine samples is higher than that of normal women urine samples, which is a novel alternative in vitro method of determining pregnancy and the quantitative analysis in the clinical laboratory agree with dielectrical studies. 2. MEASUREMENT SET UP AND PROCEDURE The measurement set-up consists of a transmission type S-band rectangular cavity resonator and a HP 8714 ET network analyzer. The cavity resonator is made from a transmission line (wave guide or coaxial line) with one or both ends closed and it can be either transmission or reflection type and in this experiment a transmis- sion type is used. The length of the resonator determines the number of resonant frequencies and is excited in the TE 10p mode. The sample holder, which is made of glass in the form of a capillary tube flared to a disk-shaped bulb at the bottom, is placed to the cavity through the nonradiating cavity slot at broader side, which can facilitate the easy movement of the holder. The resonant 786 MICROWAVE AND OPTICAL TECHNOLOGY LETTERS / Vol. 49, No. 4, April 2007 DOI 10.1002/mop