The use of diuretics (most of the literature concerns either hydrochlorthiazide or cholrthiazide) and has a long if not controversial history. At one time they were prescribed to prevent preeclampsia , and a review of many such studies involving thousands of patients revealed such therapy did not work. The same review discerned no adverse direct effects on the fetus, but all who ingest thiazide diuretics risk side effects such as low potassium levels, excess diuresis, and hypotension, especially when the drug is used in combination with other antihypertensive medications. Since preeclamptic women have low blood volumes compared to normotensive pregnant women, we do not prescribe them in these circumstances either. There are, however, uses for these drugs in pregnant women, Some chronic hypertensives are what we call Ã¢â‚¬Å“salt sensitiveÃ¢â‚¬Â, and if they were prescribed diuretics before conceptions, it is not necessary to discontinue the drug (though some physicians do stop the drug to see if their will be a pregnancy-induced fall in blood pressure, and reinstituting the drug will not be necessary). There are also instances when a pregnant woman is in heart failure, or when the blood pressure can not be controlled by the drugs of choice for pregnant women. In the latter case the combination of a thiazide with another agent leads to smoother control.
A one line summary. The thiazide diuretics can be used during pregnancy, but indications for their use are few.
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