CD4+CELL COUNT AND LEVELS OF SOME CYTOKINES AND HAEMATOLOGICAL PARAMATERS OF PREGNANT WOMEN ATTENDING NNAMDI SAZIKWE UNIVERSITY TEACHING HOSPITAL

1.1Background of the Study

Pregnancy, also known as gestation, is the time during which one or more offspring develops inside a woman (Shriver, 2015). A multiple pregnancy involves more than one offspring, such as with twins (Wylie, 2005). Pregnancy can occur by sexual intercourse or assisted reproductive technology (Shehan, 2016). Childbirth typically occurs around 40 weeks from the last menstrual period (LMP) (Abman, 2011 and Shriver, 2015). Pregnancy is typically divided into three trimesters. The first trimester is from week one through 12 and includes conception, which is when the sperm fertilizes the egg. The second trimester is from week 13 through 28, while the third trimester is from 29 weeks through 40 weeks (Shriver, 2015).

Normal pregnancy is a state characterized by many physiologic haematological changes, which appear to be pathological in the non – pregnant state (Chandra, 2012). The haematologic system must adapt in a number of ways such as provision of vitamins and minerals for foetal haematopoiesis (iron, vitamin B12, folic acid) which can exacerbate maternal anaemia, and preparation for bleeding at delivery, which requires enhanced haemostatic function, while these changes facilitate healthy pregnancy, they also increase the risk of some conditions (e.g. venous thromboembolism) (Mohammed et al., 2016). Pregnancy is influenced by many factors, some of which include culture, environment, socioeconomic status, and access to medical care (Yip, 2000). Haematological profile is measured all over the world to estimate general health, because, it is a reliable indicator and is a simple, fast and cost-effective test (Shen et al., 2010). During pregnancy, changes occur and can be observed in haematological indices such as Red Blood Cell (RBC) count, haemoglobin (Hb) concentration platelet (PLT) count, and white Blood cell (WBC) count. For example, the RBC and PLT counts are decreased, partly as a result of the physiological haemodilution that occurs in pregnancy (Dhariwal et al., 2016), while others are increased, such as the WBC count (Akingbola et al.,2006). Many of the haematological indices are also influenced by many factors such as sex, seasonal variation, lactation, healthy and nutritional status (Smith, 1993). Some studies such as Osonuga et al., (2011) and Shaw et al., (2010), have also identified the haematological indices as being affected by pregnancy.

Pregnancy is a physiologically immunocompromised state during which alterations in T – lymphocyte subsets may occur (Tanjong et al., 2012). It requires physiologc adaptations in all

maternal systems including the immune system. This process is complex and includes modifications at different levels and compartments of the maternal immune system. Although many of these changes are only partially explored and understood, recent investigations have shown that during pregnancy, maternal circulating immune cells undergo modifications in cell counts, phenotypes, functions, and ability to produce soluble factors, such as cytokines. The ultimate goal is to establish and maintain a successful pregnancy, which involves a state of selective immune tolerance, immune suppression and immunomodulation in the presence of a strong antimicrobial immunity. The mammalian immune system has evolved to co-exist with these needs by down-regulating potentially dangerous T-cell-mediated immune responses, while activating certain components of the innate immune system, such as monocytes and neutrophils. This unique dysregulation between different components of the immune system plays a central role in the maternal adaptation to pregnancy (Luppi, 2003).