Eclampsia risk factors
Eclampsia risk factors On the Web
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The various risk factors associated with the development of eclampsia encompass a personal or family history of pre-eclampsia/eclampsia, nulliparity, primigravida, long interpregnancy intervals, conditions with a large placenta such as multiple gestations(twins or triplets) and H Mole, women with preexisting conditions such as chronic hypertension, history of gestational hypertension in the previous pregnancy, renal diseases, diabetes, gestational diabetes, obesity, certain thrombophilic diseases (such as the antiphospholipid antibody syndrome, protein C deficiency, protein S deficiency, anti-thrombin deficiency), connective tissue disorders, SLE and genetics.
- History of pre-eclampsia/eclampsia: Personal history of a similar event in the past or family history is a significant risk factor for recurrence in the next pregnancy. Having pre-eclampsia in one pregnancy is a strong predictor for recurrence of pre-eclampsia in future gestations. The risk for women to develop pre-eclampsia during the second pregnancy is approximately 15% if the first pregnancy was affected by pre-eclampsia and 1.1% for those without a history of pre-eclampsia. The risk during the third pregnancy is approximately 30% for women who have had two previous affected pregnancies and remains 1.1% for those without any history. For women with the first occurrence of pre-eclampsia in their second pregnancy, the risk was 15.9% during the third pregnancy and 29.0% during the fourth when they had developed pre-eclampsia in the previous two pregnancies.
- Nulliparity: The risk for multiparous women without a history of pre-eclampsia was around 1%.
- Primigravida: The risk of pre-eclampsia is 4.1% in the first pregnancy and 1.7% in later pregnancies overall if none of the previous pregnancies have been affected by pre-eclampsia. This association is the core of theory that says that pre-eclampsia is the consequence of a maternal immune reaction against paternal antigens expressed in the placenta which might result in defective trophoblast invasion and subsequent placental dysfunction. The lower risk of pre-eclampsia among multiparous women has been attributed to desensitisation after exposure to paternal antigens in the placenta during previous pregnancies. and to smoother trophoblastic invasion after modification of maternal spiral arteries during the first pregnancy. For this reason pre-eclampsia is also known as a disease of primiparity.
- Interpregnancy interval: A long interpregnancy interval is associated with increased risk of preeclampsia, supporting the hypothesis that some factors delaying clinically recognized conception may also be in a causal pathway for preeclampsia.
- Conditions with a large placenta:
- Multiple gestations: The relative risk of preterm preeclampsia in di-chorionic and mono-chorionic twin pregnancies is similar and substantially higher than in singleton pregnancies. In a study, it was found that the incidence of pre-eclampsia in singleton pregnancies was 2.3% compared to 8% in dichorionic(DC) twin pregnancies and 6% in monochorionic(MC) twin pregnancies. Compared to singletons, the relative risk of total pre-eclampsia was 3.5 for DC twins and 2.6 for MC twins.
- Hydatiform mole: Hydatiform moles pose a high risk of early-onset preeclampsia if the pregnancy continues with the moles left untreated. Preeclampsia can develop as early as the 2nd trimester in 30–40% of pregnancies with untreated hydatiform moles. 
- Women with preexisting vascular diseases:
- Chronic hypertension: Chronic hypertension is defined as high blood pressure present before pregnancy or before 20 weeks of pregnancy. If left untreated, it can progress to gestational hypertension, pre-eclampsia, or eclampsia. Development of preeclampsia is the most prevalent complication in pregnancy in women with chronic hypertension. 17% to 25% of women with chronic hypertension develop preeclampsia compared to the general population where the risk is 3-5%.  
- Gestational hypertension: Untreated gestational hypertension can eventually progress to preeclampsia/eclampsia. Approximately 15-25% of patients with gestational hypertension will progress to preeclampsia or severe gestational hypertension. The rate of the progression depends on gestational age at the time of diagnosis and the pregnancy outcome is usually good when the diagnosis is made at ≥ 37 weeks of gestation.
- Renal diseases
- Diabetes/ Gestational diabetes/ History of Gestational diabetes: Preexisting diabetes is a risk factor for preeclampsia. In comparison to the relatively low incidence of preeclampsia in non-diabetic women (2-7%)  , preeclampsia is diagnosed in 15-20% of pregnancies in women with type 1 diabetes   and 10-14% of pregnancies in women with type 2 diabetes  .
- Obesity: The risk of preeclampsia and hence eclampsia increases by about 3-fold with obesity, and in developed countries is the leading attributable risk for the disorder. 
- Preexisting thrombophilias: A strong association between maternal thrombophilic disorders and severe preeclampsia has been established in various studies. Examples include:
- Connective tissue disorders
- Systemic lupus erythematous
- Genetics: Patients whose mother or sister had the condition are at a higher risk.
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