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Hypertensive disorders complicating pregnancy are common and along with hemorrhage and infection, result in a large number of maternal deaths. Pregnancy-induced hypertension (hypertension that develops as a consequence of pregnancy and regresses postpartum) is divided into three (3) categories: (1) Hypertension alone, (2) Pre-eclampsia, and (3) Eclampsia.
Pre-eclampsia is a disease of late pregnancy in which hypertension is associated with hepatic, neurologic, hematologic, or renal involvement, Fauci et al (1998). Rapid development of edema, particularly of the face and hands, along with a rise in blood pressure, often signals the onset of this condition. The diagnosis of pre-eclampsia has traditionally required the identification of pregnancy-induced hypertension plus proteinuria or generalized edema (Gunningham et al, 1997). Proteinuria indicates renal involvement and is an important sign of pre-eclampsia. According to Bennett and Plum (1996), pre-eclampsia describes the disease unique to pregnancy that is manifested by hypertension and evidence of multiple organ dysfunction. The term “Eclampsia” a synonym for a seizure, is the ultimate manifestation of the disease. The development of convulsions in eclampsia indicates neurologic involvement which is manifested by hyperreflexia, visual disturbances, and headache.
Gunningham et al (1997) noted that vasopasm is basic to the pathophysiology of pre-eclampsia-eclampsia. It accounts for the development of arterial hypertension because vascular constriction causes resistance to blood flow. The vascular changes are due to Angiotensin II which causes endothelial cells to contract and lead to endothelial cells damage, and interendothelial cells leak through which blood constituents, including platelets and fibrinogen to be deposited subendothelially. The widespread endothelial damage and abnormal fibrin deposits is due to decrease PGI2 (Prostacyclin) synthesis while sensitivity to Angiotensin II increases. Thus, the balance that normally exists between the platelet-aggregative and vasoconstrictor effects of Thromboxane A2 (produced by platelets) and the counteracting anti-aggregative and vasodilating effects of PGI2 (produced by endothelial cells) may be lost, contributing to platelet aggregation and hypertension. Renal biopsies in the pre-eclamptic women demonstrate the glomerular capillaries to be bloodless, with swollen endothelial and mesangial cells, as well as lipid accumulation in the glomerular cells. This is due to fibrin deposits. These fibrin deposits accumulate in the sinusoids which manifests peripheral necrosis of the liver. Fibrin deposits in the brain causes central nervous system (CNS) excitability and convulsions. The hypertension is also caused by an increase in peripheral vascular resistance associated with proteinuria and a fall in glomerular filtration rate (GFR). In proteinuria, since the glomerular filtration rate increases by about 50 percent in normal gestation, a reduction in GFR heralds the onset of pre-eclampsia even with normal levels of blood urea nitrogen (BUN) and serum creatinine. In Pre-eclampsia, urate clearance decreases because of increased proximal tubular reabsorption of urate, which in turn is probably due to the reduction of vascular volume. Hyperuricemia precedes the rise in BUN and serum creatinine.
2.2 Clinical
Significance
2.2.1 Clinical
Aspects of Pre-eclampsia:
Blood Pressure
There’s an increase in blood pressure because of arteriolar vasopasm. Diastolic pressure of 90 mmHg or more persists abnormal.
Weight Gain
Excessive weight gain precedes the development of pre-eclampsia. The suddenness of excessive weight gain (more than two pounds in any given week or six pounds in a month) is a characteristic of pre-eclampsia rather than an increase distributed throughout gestation. This is due to abnormal fluid retention and is usually manifested by swollen eyelids and puffy fingers.
Proteinuria
This develops later than hypertension and excessive weight gain. In early pre-eclampsia, proteinuria may be minimal or entirely lacking, but in most severe forms, it is usually demonstrable.
Headache
It is often frontal but may be occipital, and is resistant to relief from ordinary analgesics.
Epigastric
Pain
Right upper quadrant or epigastric pain is due to stretching of the hepatic capsule by edema or hemorrhage, and hepatic ischemia.
Visual
Disturbances
Retinal artery vasopasm is associated with visual disturbances.
2.2.2 Clinical Aspects of Eclampsia
Convulsions
Eclampsia is characterized by generalized tonic-clonic convulsions. It usually begin about the mouth in the form of facial twitchings. Afterwards, the entire body becomes rigid in a generalized muscular contraction. The face is distorted, the eyes protrude, the arms are flexed, the hands are clenched, and the legs are inverted. All muscles are now in a state of tonic contraction.
Proteinuria
Proteinuria is always present and frequently pronounced. Urine output is likely diminished, and occassionally, anuria develops. Edema occurs due to the consequence of chronic vascular or renal disease.
Blindness
This is due to varying degrees of retinal detachment and occipital lobe edema or infarction.
Coma
Coma or substantively altered consciousness follows a seizure as the result of massive cerebral hemorrhage.
Once pre-eclampsia is diagnosed, hospitalization is indicated, since the disease can progress rapidly to multisystem involvement, including eclampsia, characterized by convulsions. In drug therapy, the use of aspirin reduces the incidence of pre-eclampsia and is attributed to selective suppression of thromboxane synthesis by platelets and sparing of endothelial prostacyclin production. Early prophylactic treatment with dipyridamole and aspirin reduce recurrences.
Treatment of eclampsia consists of control of convulsions with magnesium sulfate. It is used to arrest and prevent convulsions without producing generalized central nervous system depression in either the mother or the fetus-infant. Magnesium sulfate is not given to treat hypertension. It mostly exerts a specific anti-convulsant action on the cerebral cortex. Intermittent intravenous injections of hydralazine is also used to lower the blood pressure whenever the diastolic pressure is 110 mmHg or higher, avoidance of diuretics and hyperosmotic agents,limitation of intravenous fluid administration unless fluid loss is excessive, and delivery.
Various dietary deficiencies have been suspected as a cause of pre-eclampsia but these hypotheses lack supportive data (Gunningham at al, 1997). They noted that various types of dietary supplementation do not decrease the frequency of hypertension.
High Intake of Energy, Sucrose, and
Polyunsaturated Fatty Acids is Associated with Increased Risk of
Pre-eclampsia
American Journal of Obstetrics & Gynecology (August 2001,
Part 1 Vol. 185 No. 2)
The objective of this study was to investigate prospectively whether diet in the first half of pregnancy is associated with the risk of pre-eclampsia. This study suggests that high intakes of energy, sucrose, and polyunsaturated fatty acids independently increase the risk for pre-eclampsia. However, other energy-providing nutrients were not associated with the risk for pre-eclampsia.
A Survey
of Dietary Supplement Use During Pregnancy at an Academic Medical
Center
American Journal of Obstetrics & Gynecology (August 2001,
Part 1 Vol. 185 No. 2)
This study examined the usage patterns of dietary supplements during pregnancy. It was found out that the most common products were Echinacea, pregnancy tea, and ginger. The most common reason for the use of dietary supplements is to relieve gastrointestinal symptoms. However, the use of dietary supplements among pregnant women is low but is of concern because of the lack of safety data.
Dietary
Consumption & Plasma Concentrations of Vitamin E in
Pregnancies Complicated by Pre-eclampsia
American Journal of Obstetrics & Gynecology (October 1996,
Part 1 Vol. 175 No. 4)
The aim of this study was to determine whether consumption and plasma levels of Vitamin E, a potent antioxidant, are lower in pre-eclamptic than in normal women. The researchers found no evidence that low Vitamin E consumption is related to the development of pre-eclampsia. Higher plasma Vit. E concentrations in pre-eclamptic patients are speculated to represent a response to oxidative stress.
Mutations
in the Gene for Methylenetetrahydrofolate reductase, Homocysteine
Levels, and Vitamin Status in Woman with History of Pre-eclampsia
American Journal of Obstetrics & Gynecology (February 2001
Vol. 184 No. 3)
This study found out that hyperhomocystenemia in women with pre-eclampsia has significant lower vitamin levels and is associated with mutations in the gene for methylenetetrahydrofolate reductase.
Phytoestrogens
Current Problems in Obstetrics, Gynecology, & Fertility
(March/April 2001 Vol. 24 No. 2)
This study noted the role of phytoestrogens in health.
Phytoestrogens are plant-based, naturally occurring estrogens
with a chemical structure and function similar to endogenous
estrogens, and are found to be excreted in high amounts in
vegetarians. Isoflavones (found in soy products such as tempe and
tofu), one of the types of phytoestrogens, have a complex
metabolism with significant intravariability. Epidemiologic data
suggest that cardiovascular disease is lower in populations that
consume large amounts of soy (isoflavones).
Lymphocyte
Intracellular Free Calcium Concentration is Increased in
Pre-eclampsia
American Journal of Obstetrics & Gynecology (May 1999 Vol.
180 No. 5)
These data support the idea that a calcium in diet leading to an
increased intracellular free calcium concentration during late
pregnancy contributes to the pathogenesis of pre-eclampsia.
Extracellular calcium depletion increases lymphocyte
intracellular free calcium.
The Role
of Calcium in Health and Disease
American Journal of Obstetrics & Gynecology (December 1999
Vol. 181 No. 6)
This journal noted that a low calcium intake has been implicated
in the development of hypertension and is associated with low
intakes of many other nutrients.
Nutrient
Intake and Hypertensive Disorders of Pregnancy: Evidence from a
Large Prospective Cohort
American Journal of Obstetrics & Gynecology (March
2001 Volume 184 No. 4)
The objective of this analysis was to prospectively determine the
effects of nutrient intakes on the incidences of pre-eclampsia
among women enrolled in the Calcium Pre-eclampsia Prevention
Study. This study reported that there was no significant
difference in the outcomes between cohorts randomly assigned to
supplementation with calcium or placebo. There was no significant
evidence in this study for a significant association of
hypertensive disorders of pregnancy.
Report
of the National High Blood Pressure Education Program Working
Group on High Blood Pressure in Pregnancy
American Journal of Obstetrics & Gynecology (July 2000
Vol. 183 No. 1)
This study emphasizes the use of low-dose aspirin diet, calcium
or other dietary supplements in the prevention of pre-eclampsia.
The relationship of diet and Pre-eclampsia-Eclampsia is often derived from epidemiologic studies, but these are unable to infer causal relationships and may be confounded by variables that have not been examined. I have observed that diet plays a major role in establishing the link between the pathogenesis and prevention of hypertension in pregnant women. I have noted that the previous studies done indicate strong influence of diet of an individual in the incidence and severity of hypertension. However, these are not conclusive because these studies are challenged by difficulty of accurately assesing individual dietary factors, emphasizing the pitfalls associated with selecting study populations.
Books
Benett, J. C & Plum, F. 1996. Cecil Textbook of Medicine. 20th Edition. Philadelphia, USA. WB. Saunders Company.
Fauci, A. S., et al.1998. Harrison’s Principles of
Internal Medicine 14th Ed. Volume 1.
USA. McGrwaHill Companies, Inc.
Gunningham, P. G., et al. 1997. William’s Obstetrics 20th
Edition. Connecticut, USA.
Preatice-Hall International, Inc.
Journals
Balk, Judith. March/April 2001. Phytoestrogens. Current
Problems in Obstetrics, Gynecology,
and Fertility, Volume 24 Number 2.
Clausen, T., et al. August 2001. High Intake of Energy,
Sucrose, and Polyunsaturated
AmericanJournal of Obstetrics & Gynecology, Part 1
Volume 185 Number 2.
Hojo, M., et al. May 1999. Lymphocyte Intracellular Free
Calcium Concentration is Increased In
Pre-Eclampsia. American Journal of Obstetrics &
Gynecology, Volume 180 Number 5.
Lachmeijer, A.M.A., et al. February 2001. Mutations in the
Gene for Methylenetetra-
Hydrofolate reductase, Homocysteine Levels, and Vitamin Status
in Women
With Pre-eclampsia. American Journal of Obstetrics &
Gynecology, Volume 184 Number 3.
Morris, C.D., et al. March 2001. Nutrient Intake and
Hypertensive Disorders of Pregnancy:
Evidence from a Large Prospective Cohort. American Journal
of Obstetrics & Gynecology,
Volume 184 Number 3.
Power, M.L., et al. December 1999. The Role of Calcium in
Health and Disease.
American Journal of Obstetrics & Gynecology, Volume 181
Number 6.
Schiff, E., et al. October 1996. Dietary Consumption and
Plasma Concentrations of
Part 1 Volume 175 Number 4.
Supplement.July 2000. Report of the National High Blood
Pressure Education Program Working
Group on High Blood Pressure in Pregnancy. American
Journal of Obstetrics & Gynecology,
Volume 183 Number 1.
Tsui, B., et al. August 2001. A Survey of Dietary Supplement
Use During Pregnancy at An Academic
Medical Center. American Journal of Obstetrics &
Gynecology, Part 1 Volume 185 Number 2.