LÍNEA DE TRANSMISIÓN NUEVA YUNCÁN – NUEVA YANANGO

As stated before, obesity during pregnancy is associated with adverse maternal outcomes and some of them are discussed in the following the sub-sections.

1.6.1.1 Pregnancy induced hypertension (PIH) and Pre-eclampsia

Maternal obesity is a well-established risk factor for the development of pregnancy induced hypertension (PIH); defined as a condition where a woman`s blood pressure is 140/90 mm Hg or greater, after 20 weeks of pregnancy depending on measurement in two different occasions which are 4-6 hours apart (NHS, 2015). Currently, PIH is reported to affects 5-10% of pregnancies and remains a significant leading factor for poor pregnancy outcome in USA (Ehrenthal et al., 2011). The causes of PIH are not clearly understood, but research suggested that the condition is related to placental and maternal factors such as null parity, maternal age >35 or <20 and family history of PIH (ACOG, 2002 cited in Ehrenthal et al, 2011). Many studies have found an association between maternal obesity and PIH. Bhattachary et al. (2007) found a linear increase in PIH with increasing BMI, resulting in a 3.1 (95% CI: 2.0-4.3) for PIH in the morbidly obese women compared to normal weight women or recommended BMI. Callaway et al. (2006) found an increase in PIH with increasing BMI: obese women were three times more likely to have PIH. Furthermore, obesity was reported as a strong risk factor for PIH in a

population- based study of 96,801 pregnant women who delivered singleton babies conducted in the USA (Baeten et al., 2001). In addition, a study by Sebire et al. (2001) examined pregnancy outcome in 287,213 singleton pregnancies in the UK and found that PIH increased with increasing BMI which corresponded with the findings of Hauger et al. (2008) where elevated BMI is seen as a strong independent risk factor for PIH. Moreover, a large prospective cohort study of 16,102 pregnant women found a significant association of PIH with increasing BMI. However, Basu et al. (2010) reported that there was no difference regarding the incidence of hypertension within BMI groups and the author linked the rate of hypertension to other causal factors in their setting. However, an article by Yogev and Catalano (2009) stated that the prevalence of PIH is increased among high BMI women who have experiences of hypertension pre-pregnancy. If PIH is not treated, it might result in a condition called pre-eclampsia. Pre-eclampsia is defined as a condition in pregnancy characterised by hypertension with albuminuria (leakage of large amount of the protein albumin into the urine) and oedema of the face, hand and feet (NHS, 2015). Several studies have shown that pre-eclampsia is more common in obese women compared to normal weight women (Castro and Avina, 2002; Catalano and Ehrenberg, 2006; Dietl, 2005).

1.6.1.2 Gestational diabetes mellitus (GDM)

Maternal obesity has consistently been shown to be a risk factor for the development of Gestational diabetes. Gestational diabetes is a carbohydrate intolerance of varied severity that begins or is first recognised during pregnancy or defined as a condition where there is too much glucose in the blood, and this condition has adverse effects on women’s health during pregnancy (NHS, 2014). The mechanism of gestational diabetes is the result of insufficient insulin secretion to compensate for increasing insulin resistance during

pregnancy. The pathophysiology of GDM involves abnormalities of insulin sensitive tissues. Beta cell sensing of glucose is also abnormal and is manifested as an inadequate insulin response for a given degree of glycaemia (Driul et al., 2008), thus affecting both the mothers` and babies` health. As Castro and Avina (2002) and Dietl (2005) stated, GDM is more common among obese women compared to normal weight pregnant women. Even though, DM has contributing factors such as age, ethnic origin and family history, obesity creates an independent risk factor as the frequency of gestational diabetes is 2-3 times higher in obese and overweight women than normal weight pregnant women. In an article which addressed issues concerning pregravid obesity and weight gain during pregnancy and its implication on pregnancy outcomes in USA, 10% of obese women were said to have been affected by gestational diabetes (Yogev and Catalano, 2009). Similarly, Morin and Reilly (2007) and Reece (2008) stated that pregnant women who are obese are more liable to have gestational diabetes during pregnancy.

Rode and his colleagues (2005), who obtained data from a cohort study on Danish women, identified that obese women were almost fifteen times more likely to develop gestational diabetes when compared to normal weight women (Rode et al., 2005). Furthermore, Ramos and Caughey (2005) conducted a retrospective study on the interrelationship between ethnicity and obesity and its effect on obstetric outcomes. They found that Asian and Latina women were more at risk for gestational diabetes than obese Caucasian women; reasons behind this are unclear (Ramos and Caughey, 2005). Their findings showed that obesity and ethnicity may have a role in developing gestational diabetes during pregnancy to greater degree than alone. Moreover, Leikin and his contemporaries stated that normal weight women with GDM can decrease their risk of adverse outcomes if they control their blood glycaemia through diet, insulin or anti-

diabetic drugs (Leikin 1987 cited in Sirimi and Dimitrios, 2010). Their findings showed that obesity and diabetes play independent role in foetal size. Unfortunately, in Kurdistan region, according to the author’s experiences as a clinical instructor at Diabetic centre in Maternity teaching hospital, there appears to be an increase in mothers with gestational diabetes. In 2007, there were approximately 3-5 women per day with gestational diabetes who attended the centre for insulin injection. However, in 2012 according to health care provider’s viewpoints, it reached 15-20 women per day indicating a significantly increase of 3-4 times. It appears that this observation may suggest that GDM is increasing in pregnancy in the region, and obesity may be a factor which is influencing the increase. By introducing an education programme for obese pregnant women, this may play a part in stemming the increase in GDM and perhaps reducing its prevalence.

1.6.1.3 Preterm labour

Preterm can be defined as delivery of a live baby before 37 weeks of gestation. An early preterm birth can be defined as the delivery of baby before 32 weeks of gestation. Preterm birth can occur as a result of preterm labour or elective delivery. It is regarded as a major cause of neonatal mortality and morbidity (Simmons et al., 2010). There is contradictory data in the literature regarding preterm birth and maternal obesity. Some scholars suggest that obese women are at increased risk of delivering preterm babies (Driul et al. 2008; Baeten et al., 2001). Other authors report decreased number of preterm births among obese women (Sebire et al., 2001), while others have found no association between incidences of preterm birth and BMI categories (Bianco et al., 1998). On other hands, Loftin et al. (2010) suggested that some preterm births results from other conditions like PIH, Caesarean section (CS) and multiple gestations.

A systematic review conducted by Lambert and Germain, (2010), including 84 studies, aimed to find out the relationship between obese mothers and preterm birth in singleton pregnancies in developing and developed countries. The review found that there were no significant differences between obese and overweight compared to normal weight women regarding their risk of preterm birth. However, among obese and overweight women the risk of induced preterm birth was increased. The higher the BMI, the higher the risk of induced preterm birth before 37 weeks. A retrospective cohort study illustrated that there is a relationship between preterm birth, BMI and parity; obese nulliparous women were at increased risk of preterm deliveries compared to normal weight women, whereas, among obese multiparous women the risk was highest among those with normal weight (Cnattingius et al., 2015).