Hypertension and its Treatment during Pregnancy
During pregnancy marked physiological changes occurs and for successful and happy outcome of pregnancy the female body has to undergo successful physiological adaptation. If the adaptation process is not perfect or appropriate medical disorders may occur during pregnancy. Some of the medical disorders are fairly common during pregnancy and increase in blood pressure is one such common medical problem during pregnancy.
During pregnancy the cardiac output (which the quantity of blood heart has to pump every minute) increases by approximately 40% and the heart rate or pulse rate increases by approximately 10 beats per minute mainly during the last three months of pregnancy. But despite the increase in heart rate the increase in cardiac output is mainly due to increase in stroke volume, which is the amount of blood heart pumps out in every heart beat.
During second trimester of pregnancy there is reduction in the vascular resistance and there is reduction in blood pressure in normal pregnant women. Blood pressure is the result of cardiac output and degree of vascular resistance and if there is reduction in the vascular resistance, blood pressure falls. That is the reason blood pressure of 140/90 mm of Hg is considered very high during pregnancy (mainly during second trimester), whereas the same pressure is considered only the beginning of high blood pressure in general population. High perinatal (4 weeks before delivery to 4 weeks after delivery is the perinatal period) mortality and morbidity is associated even at blood pressure of 140/90 mm of Hg.
The diagnosis of hypertension (high blood pressure) is different in pregnant women in compare to general population. Blood pressure in a pregnant woman should be checked in sitting position, because if blood pressure is taken in lateral recumbent position, as is the practice in general, blood pressure may be lower than in sitting position. The diagnosis of high blood pressure in pregnant woman requires measurement of at least two elevated blood pressure of at least 6 hours apart. Blood pressure of 140/90 mm of Hg is considered very high blood pressure during pregnancy as generally blood pressure is low during pregnancy due to reduction in vascular resistance. 140/90 mm of Hg is considered only mild hypertension in a normal subject, but in pregnant women the same pressure is considered very high blood pressure.
High blood pressure in pregnancy may cause intrauterine growth retardation, increased perinatal mortality etc. Pregnant women with hypertension are also at risk of development of medical problems like preeclampsia and abruptio placenta. To prevent the complications of hypertension, women with chronic hypertension should be thoroughly evaluated for to identify the remediable causes of hypertension and also to prevent adverse effects of anti hypertensive drugs during pregnancy.
Treatment of hypertension:
Pregnancy is an extraordinary situation and requires meticulous care in treating high blood pressure. The normally prescribed drugs for hypertension (ACE inhibitors like enalapril, angiotensin-receptor blockers like losratan) can not be used due to fear of development of fetal abnormality. The most commonly use antihypertensive drugs during pregnancy are alpha-Methyldopa, labetalol, and nifedipine, which have very little if any effect on growing fetus and considered safe during pregnancy. If the hypertension is due to pregnancy it will normalize after delivery.
Renal function should be evaluated to find out the chance of developing preeclampsia and to treat and manage early, should preeclampsia develop.