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- Materials and methods
Objective Pre-eclampsia contributes significantly to maternal, foetal and neonatal morbidity and mortality. The risk factors for pre-eclampsia have not been well documented in Uganda. In this paper, we describe the risk factors for pre-eclampsia in women attending antenatal clinics at Mulago Hospital, Kampala.
Methods This casecontrol study was conducted from 1st May 2008 to 1st May 2009. 207 women with pre-eclampsia were the cases, and 352 women with normal pregnancy were the controls. The women were 15–39 years old, and their gestational ages were 20 weeks or more. They were interviewed about their socio-demographic characteristics, past medical history and, their past and present obstetric performances.
Results The risk factors were low plasma vitamin C (OR 3.19, 95% CI: 1.54–6.61), low education level (OR 1.67, 95% CI: 1.12–2.48), chronic hypertension (OR 2.29, 95% CI 1.12–4.66), family history of hypertension (OR 2.25, 95% CI: 1.53–3.31) and primiparity (OR 2.76, 95% CI: 1.84–4.15) and para≥5 (3.71, 95% CI:1.84–7.45).
Conclusion The risk factors identified are similar to what has been found elsewhere. Health workers need to identify women at risk of pre-eclampsia and manage them appropriately so as to prevent the maternal and neonatal morbidity and mortality associated with this condition.
Objectif: La pré-éclampsie contribue de manière significative à la santé maternelle, la morbidité fœtale et néonatale et la mortalité. Les facteurs de risque de pré-éclampsie n’ont pas été bien documentés en Ouganda. Dans cet article nous décrivons les facteurs de risque de pré-éclampsie chez les femmes en consultations prénatales à l’hôpital de Mulago, à Kampala.
Méthodes: Cette étude cas-témoins a été menée à partir du 1er mai 2008 au 1er mai 2009. 207 femmes atteintes de pré-éclampsie étaient les cas et 352 femmes avec une grossesse normale étaient les contrôles. Les femmes étaient âgées de 15 à 39 ans et leur âge gestationnel était de 20 semaines ou plus. Elles ont été interviewées sur leurs caractéristiques sociodémographiques, les antécédents médicaux et leurs expériences obstétriques passées et présentes.
Résultats: Les facteurs de risque étaient: le faible taux plasmatique en vitamine C (OR = 3,19; IC95%: 1,54 à 6,61), le niveau d’éducation faible (OR = 1,67; IC95%: 1,12 à 2,48), l’hypertension chronique (OR = 2,29; IC95%: 1,12 4,66), les antécédents familiaux d’hypertension (OR = 2,25; IC95%: 1,53 à 3,31), la primiparité (OR = 2,76; IC95%: 1,84 à 4,15) et la multiparité≥ 5 (OR = 3,71; IC5%: à 1,84 à 7,45).
Conclusion: Les facteurs de risque identifiés sont similaires à ce qui a été trouvé ailleurs. Les agents de santé devraient identifier les femmes à risque de pré-éclampsie et les prendre en soin de manière appropriée afin d’éviter la morbidité maternelle et néonatale et la mortalité, associées à cette condition.
Objetivo: La pre-eclampsia contribuye significativamente a la morbilidad y mortalidad materna, fetal y neonatal. Los factores de riesgo de la pre-eclampsia no están bien documentados en Uganda. En este artículo describimos los factores de riesgo para la pre-eclampsia en mujeres que son atendidas en la clínica prenatal del Hospital de Mulago, en Kampala.
Métodos: Estudio caso control realizado entre el 1 de Mayo 2008 y el 1 Mayo 2009. Los casos fueron 207 mujeres con pre-eclampsia y los controles 352 mujeres con embarazos normales. Las mujeres tenían edades comprendidas entre los 15- 39 años, y su edad gestacional eran de 20 semanas o más. Se les entrevistó acerca de sus características socio demográficas, historial médico y resultados obstétricos presentes y pasados.
Resultados: Los factores de riesgo fueron unos niveles bajos de vitamina C en plasma (OR 3.19, 95% IC: 1.54–6.61), un bajo nivel de educación (OR 1.67, 95% IC: 1.12–2.48), hipertensión crónica (OR 2.29, 95% IC 1.12–4.66), historia familiar de hipertensión (OR 2.25, 95% IC: 1.53–3.31) y primiparidad (OR 2.76, 95% IC: 1.84–4.15) y, paridad ≥5(3.71, 95% IC:1.84–7.45).
Conclusión: Los factores de riesgo identificados son similares a lo hallado en otros lugares. Los trabajadores sanitarios deben identificar a las mujeres con riesgo de pre-eclampsia y darles un manejo apropiado para prevenir la morbilidad y mortalidad asociada a esta condición.
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- Materials and methods
Pre-eclampsia complicates 5–8% of all pregnancies although the incidence may be higher in poor regions (Duley 1992). It is among the leading causes of maternal, foetal and neonatal morbidity and mortality worldwide especially, in poor settings (Khan et al. 2006). In Mulago Hospital in Uganda in 2000, it contributed 17.6% to maternal morbidity and 21.4% to maternal mortality (Kaye et al. 2003).
Few studies have been reported in poor resource settings about risk factors for pre-eclampsia. The major objective of this study was to determine the risk factors for pre-eclampsia in Mulago Hospital. This may help in the surveillance of mothers at risk and reduce the maternal morbidity and mortality associated with this condition.
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- Materials and methods
The background factors of the respondents are shown in Table 1. The minimum age of the women with pre-eclampsia was 15 years and the maximum age was 39 years with a mean of 24.07 (SD 5.15). The minimum age of the controls was 16 years, and the maximum age was 36 years with the mean of 23.7 (SD 4.34). Women with pre-eclampsia were more likely to be single, to live further away from the hospital, to consume alcohol and to have a deficient vitamin C status than women with normal pregnancy.
Table 1. The background factors of women with pre-eclampsia and women with normal pregnancy
|Characteristic||Pre-eclampsia n (%)||Normal pregnancy n (%)||Crude Odds Ratio||P-value|
|Plasma Vitamin C*|
| ≤1.1 × 103μg/l||39 (18.8)||34 (9.7)||2.34 (1.32–4.19)||0.043|
| 1.1–2.0 × 103μg/l||117 (56.5)||214 (60.8)||1.12 (0.74–1.67)|
| >2.0 × 103μg/l||51 (24.8)||104 (29.5)||1|
| ≤19||44 (21.3)||68 (19.3)||1.27 (0.78–2.02)||0.33|
| 20–24||80 (38.7)||157 (44.6)||1|
| 25–29||46 (22.2)||81 (23.0)||1.11 (0.71–1.71)|
| ≥30||37 (17.9)||46 (13.1)||1.58 (0.94–2.62)|
| Primary or none||83 (40.1)||119 (33.8)||1.31 (0.91–1.86)||0.135|
| Secondary or above||124 (59.9)||233 (66.2)||1|
| Single||44 (21.3)||49 (13.9)||1.67 (1.06–2.62)||0.025|
| Married||163 (78.7)||303 (86.1)||1|
|Distance from Mulago*|
| 5 km or less||97 (46.9)||215 (61.1)||1||0.001|
| More than 5 km||110 (53.1)||137 (39.9)||1.78 (1.26–2.52)|
| Low||69 (33.3)||100 (28.4)||1.08 (0.71–1.66)||0.18|
| Middle income||65 (31.4)||137 (38.9)||0.74 (0.49–1.13)|
| High||73 (35.3)||115 (32.7)||1|
| Yes||03 (1.2)||03 (0.9)||1||0.6|
| No||204 (98.8)||349 (99.1)||0.59 (0.12–2.93)|
| Yes||31 (15.0)||32 (9.1)||1.8 (1.03–2.97)||0.08|
| No||176 (85.0)||320 (90.9)||1|
| ≤23||05 (2.56)||12 (3.5)||1||<0.001|
| 24–25||10 (5.13)||35 (10.2)||0.66 (0.19–2.41)|
| 26–27||08 (4.10)||67 (19.6)||0.29 (0.08–1.02)|
| ≥28||172 (88.2)||228 (66.7)||1.81 (0.63–5.2)|
| Positive||18 (8.7)||33 (9.4)||0.92 (0.48–1.74)||0.8|
| Negative||189 (91.3)||319 (90.6)||1|
The medical and obstetric factors in women with pre-eclampsia and women with normal pregnancy are shown in Table 2. Women who had chronic hypertension, who had a family history of hypertension, were primigravidae and who were gravid five or more were more likely to develop pre-eclampsia.
Table 2. Medical and obstetric factors in women with pre-eclampsia and women with normal pregnancy
|Characteristic||Cases n (%)||Controls n (%)||Crude Odds Ratio||P-value|
|History of diabetes|
| Yes||5 (2.4)||4 (1.1)||2.15 (0.5–9.65)||0.2|
| No||202 (97.6)||348 (98.9)||1|
|History of hypertension*|
| Yes||22 (10.6)||17 (4.8)||2.3 (1.2–4.5)||0.009|
| No||185 (89.4)||335 (95.2)||1|
|Family history hypertension*|
| Yes||101 (48.8)||106 (30.1)||2.2 (1.6–3.2)||<0.001|
| No||106 (51.2)||246 (69.9)||1|
| Primigravidae||112 (54.1)||148 (42.1)||2.1 (1.4–3.0)||<0.001|
| Gravida 2–4||68 (32.9)||186 (52.8)||1|
| Gravida 5+||27 (13.0)||18 (05.1)||4.1 (2.1–7.9)|
Factors that were independently associated with the risk of pre-eclampsia are shown in Table 3. Women who had low plasma vitamin C were 3.2 times as likely to develop pre-eclampsia as women with normal or high vitamin C levels. Women who had primary level of education or no education at all were 1.7 times more likely to develop pre-eclampsia compared to women who had secondary level of education or higher. Women who had chronic hypertension were 2.3 times more likely to develop pre-eclampsia compared to women who did not have chronic hypertension. Similarly, women who had a family history of hypertension were 2.2 times more likely to develop pre-eclampsia as women who did not. Lastly, primigravidae were three times more likely to develop pre-eclampsia than women who were gravida 2–4, whereas women who were gravid five or more were four times more likely to develop pre-eclampsia than women who were gravida 2–4.
Table 3. The factors independently associated with pre-eclampsia
|Characteristic||Adjusted Odds Ratio|
|Vitamin C (μg/l)|
| ≤1.1 × 103||3.19 (1.54–6.61)|
| 0.11 × 103||1.23 (0.80–1.88)|
| >2.0 × 103||1|
| Primary or none||1.67 (1.12–2.48)|
| Secondary or above||1|
|Distance to Mulago|
| 5 km or less||1|
| More than 5 km||2.03 (1.39–2.96)|
| Yes||1.65 (0.93–2.94)|
|History of hypertension|
| Yes||2.29 (1.12–4.66)|
|Hypertension in family|
| Yes||2.25 (1.53–3.31)|
| Primegravidae||2.76 (1.84–4.15)|
| Gravida 2–4||1|
| Gravida 5+||3.71 (1.84–7.45)|
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- Materials and methods
In this paper, we examined the risk factors for pre-eclampsia in Uganda and found that the predictors for pre-eclampsia were similar to what has been described in other low-resource and high-resource countries. Women who had primary level of education or no education at all were two times likely to develop pre-eclampsia as women who had secondary or higher level of education. Other researchers in low-resource settings (Mahomed et al. 1998; Conde-Agudelo & Belizan 2000; Anorlu et al. 2005) have not found this association between the level of education and risk of developing pre-eclampsia. However, researchers from high-resource countries (Hartikainen et al. 1998; Ceron-Mireles et al. 2001) agree with this finding while others do not (Sibai et al. 1995). Though, education level was used as a measure of the socioeconomic status. Other studies (Haelterman et al. 2003; Silva et al. 2008), but not ours, found low socioeconomic status associated with pre-eclampsia. The association of low socioeconomic status and pre-eclampsia is unclear but could be due to poor nutrition and stressful life conditions which may lead to over reactivation of the sympathetic nervous system (Leeners et al. 2007).
Primiparity was associated with a triple risk of developing pre-eclampsia after controlling for confounders. This is similar what has been found in other studies in both low- (Conde-Agudelo & Belizan 2000; Anorlu et al. 2005) and high-resource countries (Hartikainen et al. 1998; Stamilio et al. 2000). This is because of exposure to chorionic villi for the first time, which is foetal in origin and may be due to immunological incompetence seen in first pregnancy (Dekker & Sibai 1998). Pre-eclampsia is a disease of the first pregnancy. Even an abortion in a previous pregnancy has been found to be protective (Sibai et al. 1995). Women who were gravida five or more were four times more likely to develop pre-eclampsia compared to women who were gravida 2–4. This is similar to what was found in Jordan (Abu-Heija & Chalabi 1997), but differed from what was found in Nigeria (Anorlu et al. 2005) and Latin America (Conde-Agudelo & Belizan 2000). Women who were gravida five or more were probably older and more likely to develop essential hypertension and pre-eclampsia.
Women who had chronic hypertension were 2.3 times more likely to develop pre-eclampsia after controlling for confounders. This was similar to what was found by other researchers in low- (Conde-Agudelo & Belizan 2000; Anorlu et al. 2005) and high-resources settings (Sibai et al. 1998; Sibai 2002), perhaps because of insulin resistance. It activates the sympathetic nervous system. It may also activate the tubular sodium re-absorption and aggravate the cytokine-mediated oxidative stress (Dekker & Sibai 1998). Pre-eclampsia develops early in women with chronic hypertension and is severe, and the women are at increased risk of adverse maternal and perinatal outcomes (Sibai et al. 1998). Similarly, women with a family history of hypertension were 2.2 times more likely to develop pre-eclampsia after controlling for confounders. This is similar to what has been found in other studies in low-resource settings (Conde-Agudelo & Belizan 2000; Anorlu et al. 2005) and is in agreement with what was found in high-resource countries (Qiu et al. 2003; Roes et al. 2005).
Women who had low plasma vitamin C level were 2.9 times more likely to develop pre-eclampsia. Poston & Raijmakers (2004) show that oxidative stress plays a role in the aetiology of pre-eclampsia. Vitamin C is the first line in defence against oxidative stress and is consumed in the process. It also recycles reduced vitamin E and glutathione which are other antioxidants and this consumes it further. While initial studies of supplementation with vitamin C and E showed a reduction in oxidative stress and pre-eclampsia (Chappell et al. 1999, 2002), subsequent studies have failed to do so (Rumbold et al. 2006; Villar et al. 2009). This could have been because the populations selected were from high-resource settings with good nutritional status or were a heterogeneous group with different risks and there could have been some benefit in some groups. Women who lived more than 5 km from Mulago hospital were two times more likely to develop pre-eclampsia than women who lived close by. It is probable that women with pre-eclampsia were more likely to be referred to Mulago hospital and hence came from health centres which were further from hospital than women with normal pregnancy.
Alcohol consumption during pregnancy was not associated with pre-eclampsia in this study. Other investigators (Salihu et al. 2011) have found a protective effect of prenatal alcohol consumption with pre-eclampsia, although the other pregnancy outcomes were not good. The explanation of this protective effect on alcohol consumption is not clear but could be due to recall bias in the comparison group or deliberate under reporting.
This study was conducted in a referral hospital, and the women seen at this hospital may not be representative of the ones seen in the community and this could bring in a selection bias; hence, there was a restriction of distance. Women with eclampsia and HELLP syndrome were excluded and this could have affected the representativeness of the cases.