RECURRENT MISCARRIAGE AND AUTOIMMUNITY

Abstract

Recurrent pregnancy loss (RPL) is defined as having multiple pregnancy losses from either biochemical or clinical factors, while recurrent miscarriage (RM) is defined as having multiple successive pregnancy losses in early gestation up to 20 weeks. In obstetric practice, pregnancy loss is not an unusual case; 38% of pregnant women experienced spontaneous abortion before (Sugiura-Ogasawara et al. 2013). Despite this, it is estimated that one in 20 conceived females go through two consecutive miscarriages and only 1% of the sufferers would see a third or further miscarriages (De Groot et al. 2012; Ford and Schust 2009; Sugiura-Ogasawara et al. 2013). In other words, human females complete their pregnancy with embryo wastage; around 30% of the losses before implantation, 30% before the sixth gestational week (biochemical pregnancy loss), and 10–15% of clinical pregnancies up to 12 weeks of gestation (Teklenburg et al. 2010; Arslan and Branch 2020). RPL has several types of etiological causes (Ali et al. 2020). A history of RPL physically and psychologically lays a burden on pregnant women. This is why, screening for miscarriage risk factors is essential for the patients having a history of RM. By means of communication to the fetus through placental and decidual tissue in a proper and balanced way the mother may expect delivery. Otherwise, the interrupted or disrupted signals may lead to pregnancy failure (Rull et al. 2012; Grimstad and Krieg 2016). Many factors induce RM including aberrations of parental chromosomes, uterine malformations, infectious diseases, and endocrine and autoimmune disorders; however, several of these remain unexplained in about 50% of RM cases (Arias-Sosa et al. 2018; Ali et al. 2020; Liu et al. 2020). Second to chromosomal and genetic abnormalities, the underlying miscarriage cause is autoimmunity particularly that associated with antiphospholipid antibodies. The functional defects in various T-cell subsets in addition to the alteration of natural killer cell behavior as presented in recent studies are in relation to the indefinite mechanisms by which general autoimmunity predisposes to RM (Bansal et al. 2011).