Pregnancy risk from blood pressure drugs?Babies exposed in the first trimester trimester /tri·mes·ter/ (-mes´ter) a period of three months. tri·mes·ter (tr  -m s of their mother's pregnancy to blood pressure blood pressure, force exerted by the blood upon the walls of the arteries. The pressure in the arteries originates in the pumping action of the heart, and pressure waves can be felt at the wrist and at other points where arteries lie near the surface of the body (see pulse). Since the heart can pump blood into the large arteries more quickly than it can be absorbed and released by the tiny arterioles and capillaries, considerable inner pressure always exists in drugs called ACE inhibitors ACE inhibitor ( s)n. are at an increased risk of birth defects, according to a new study. The drugs already carry a warning against their use dining the second and third trimesters of pregnancy because of the danger of kidney damage in the fetus. Angiotensin angiotensin /an·gio·ten·sin/ (-ten´sin) a decapeptide hormone (a. I) formed from the plasma glycoprotein angiotensinogen by renin secreted by the juxtaglomerular apparatus. It is in turn hydrolyzed by a peptidase in the lungs to form an octapeptide (a. II), which is a powerful vasopressor and stimulator of aldosterone secretion by the adrenal cortex. This is in turn hydrolyzed to form a heptapeptide (a.-converting enzyme inhibitor; any of a class of drugs that reduce peripheral arterial resistance by inactivating an enzyme that converts angiotensin I angiotensin I n. to the vasoconstrictor angiotensin II, A decapeptide that is the precursor to angiotensin II angiotensin II n. but is itself physiologically inactive. An octapeptide that is a potent vasopressor and a powerful stimulus for production and release of aldosterone from the adrenal cortex. A review of the records of 29,507 infants in Tennessee showed that 209 babies had been exposed to ACE inhibitors during the first trimester in the womb. The records reveal that the mothers of another 202 babies had taken other blood pressure drugs during the first trimester and the rest of the infants had no exposure to blood pressure medicines. The records showed that 7.1 percent of the children exposed to ACE inhibitors had congenital defects--mainly of the heart and central nervous system--compared with only 1.7 percent of the babies exposed to other blood pressure drugs and 2.6 percent of those not exposed, researchers report in the June 8 New England Journal of Medicine. ACE inhibitors target angiotensin converting enzyme (ACE). Normally, ACE converts the compound angiotensin I into angiotensin II, which induces the blood vessels to constrict con·strict (k  n-str kt )v. and blood pressure to rise. By suppressing ACE, the inhibitors relax blood vessels and lower blood pressure. To make smaller or narrower, especially by binding or squeezing. Why ACE inhibitors might damage a fetus is unclear, says study coauthor William O. Cooper, a pediatrician at Vanderbilt University School of Medicine in Nashville. "Most organ formation occurs in the first trimester" he says. "It's not likely that relaxing blood vessels led to these problems. It looks like angiotensin plays a role in organ formation." |
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