A Review on Controversies about the Role of Immune and Inflammatory Systems in Implantation Process and Durability of Pregnancy

Abstract

IntroductionAmong the controversies in reproduction science, role of immune and inflammatory systems in implantation process and durability of pregnancy is a hot topic nowadays. Some researchers and practitioners believe that administration of drugs such as prednisolone, aspirin or heparin can improve success rate of implantation and pregnancy through inhibiting coagulation, inflammatory and immune systems; while others believe that such systems not only do not have negative effect on rejecting blastocyst and embryo by itself but also are necessary for implantation and remodeling of uterine spiral arteries through secreting adhesive and angiogenic factors. Such controversies are proposed both in natural pregnancies resulting in spontaneous abortion as well as in successful and/or unsuccessful assisted reproductive technologies (ARTs). Recurrent spontaneous abortion (RSA) is defined as having 3 or more history of abortion (1). About the other issue, some researchers and practitioners are grumbling of low success rate of ARTs like in vitro fertilization (IVF). Infertility is a problem for 10%-15% of couples; most of which -but not all -require ART (2). The average fertilization rate of ART in previous researches has been reported about 30% (3) and this report is for 1998. It has been claimed in an article published in 2015 that this rate has improved in the recent decade (4). Even though at the first glance this rate seems low, but the interesting point is that in the claim of a valid reference (5) the chance of natural pregnancy for each intercourse per month does not go up more than 33%. Also this number has been reported in some studies up to 40% (6). Thus, we should not be grumbling of the low fertilization rate of ARTs. Finally we intend to represent and report our insights, reasoning and suggestions in the present review. MethodsThis systematic and critical review includes investigation of scientific data bases and tracing the citations and the references of the articles in order to find the root of the truth. Through this wisdom, we showed the mere that a content proposed in an indexed article is not a reason that this content is valid and able to be cited. Indeed, the researcher should regard and notice the reasoning, citations and protocol of his/her references during the literature review. This is the benefit point of systematic review rather than holistic and narrative reviews. Since some data were few, the time period of publications was not important to us. As the searching strategy, we used the Web of Science Core Collection and Google Scholar for finding articles other than ISI-WOS and the tracing mentioned in the above paragraph. Results and DiscussionRole of Immune System and Leukocytes In 2015, Ghafourian et al (1) by measuring the level of natural killer-cells (NKs) in blood of the RSA and the control group concluded that RSA patients in normal (non-preg- AbstractAmong the controversies about reproduction sciences, role of immune and inflammatory systems in implantation process and durability of...

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