Atrial natriuretic peptide and atrial size during normal pregnancy

Article Abstract:

Atrial natriuretic peptide (ANP) is a protein that is made by cells located in the atrium of the heart. When the amount of fluid retained in the body increases the heart (atria) stretches or expands in size to accommodate the increased amount of fluid. This stretching or expanding of the heart muscle causes cells to make ANP. This protein causes blood vessels to dilate and it increases the amount of fluid (urine) excreted in an attempt to reduce the amount of fluid in the body and return the heart to its normal size. During pregnancy, hormones (aldosterone and estrogen) cause the kidneys to retain fluid so that the volume of fluid in the body increases, causing the heart to expand in size. Therefore, it would be expected that during pregnancy, as the heart size increases, so would blood levels of ANP. However, studies that have measured blood levels of ANP during pregnancy have yielded conflicting results. Some studies have reported that ANP levels increase while others have reported that ANP levels do not change during pregnancy. To investigate the relationship between ANP and heart (atrial) size, blood levels of ANP and changes in heart size were measured in 21 pregnant women. The results showed that blood levels of ANP were elevated during the second trimester of pregnancy and then decreased, while heart size was found to increase during the third trimester of pregnancy. These unexpected findings may be explained as an adaptive process that occurs during pregnancy to maintain the increased fluid volume in the circulation. (Consumer Summary produced by Reliance Medical Information, Inc.)

Heart, Physiological regulation, Pregnancy, Natriuretic peptides, Body fluids

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A longitudinal study of platelet behaviour and thromboxane production in whole blood in normal pregnancy and the puerperium

Article Abstract:

Platelets are blood cells that are important in blood coagulation and formation of blood clots. Studies have shown that platelets have increased activity during pregnancy, which may contribute to an increased risk of blood clot formation and other circulatory disorders. In addition, platelets release a substance called thromboxane A2, which increases the aggregation of platelets and constricts blood vessels. Increased activity of platelets and production of thromboxane A2 may also contribute to the development of pre-eclampsia, toxemia of pregnancy characterized by high blood pressure, headaches, albumin (a blood protein) in the urine, and accumulation of water in the lower extremities. Agents that act against platelets have been shown to prevent the development of pre-eclampsia. The activity of platelets, including their ability to aggregate and to release thromboxane A2, and the production of thromboxane B2 (a metabolic product of thromboxane A2) were assessed before, during, and after the normal pregnancies of eight women. The response of platelets to arachidonic acid and adrenaline, agents that increase platelet aggregation, was increased in the last three months of pregnancy and remained high six weeks after delivery. Platelet response returned to normal within 12 weeks of delivery. The blood levels of thromboxane B2 were not altered throughout pregnancy or after delivery. (Consumer Summary produced by Reliance Medical Information, Inc.)

Causes of, Preeclampsia, Thromboxanes, Blood platelets, Cell aggregation

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Abdominal pain of unknown aetiology in pregnancy

Article Abstract:

Pregnant women with lower abdominal pain are generally diagnosed with urinary tract infection, early labor, appendicitis or placenta abruption. However, for many of these patients the cause of abdominal pain is not found. To assess whether these patients have poor pregnancy outcomes, 140 women with unexplained abdominal pain were compared with women having no pain. Infant birth weights, age of the mother, number of previous pregnancies, marital status, employment status and smoking habits were evaluated in the two groups. All the pregnancies studied had live births. The group with unexplained abdominal pain contained a larger percentage of women who smoke, are unmarried and whose partners are unemployed. There were no differences between the two groups in infant birth weights, gestational age at delivery or type of delivery. These results indicate pregnancy management need not be altered in the presence of unexplained lower abdominal pain.

Case studies, Abdominal pain

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