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	pregnancy & birth birth preparation

Diagnotsic Tests Of The Third Trimester

Testing for Glucose Tolerance
Throughout your pregnancy, your urine has most likely been tested for the presence of sugar. If high sugar levels are detected in your urine, you may be given follow-up tests to determine whether you are at risk for gestational diabetes, a temporary condition that will disappear after the baby is born.

Some practitioners believe that gestational diabetes can increase the risk of fetal macrosomia, or a larger-than-average baby. To prevent the baby from growing too large, and to avoid the need for cesarean section, women deemed at risk for gestational diabetes are often placed under careful dietary restrictions, monitored using blood tests and ultrasound scans, and occasionally given insulin. In some cases labor is induced early, or elective cesarean section is performed.

Gestational diabetes has been the cause of a great deal of controversy. Many experts question its very existence, calling it "a diagnosis in search of a disease." In addition, many birth practitioners believe that elevated blood-sugar levels actually represent a healthy response to the inherent dynamics of pregnancy. Glucose may remain in the blood for longer periods so that it is more accessible to the developing baby. These experts add that pregnant women should not be tested using the same standards as nonpregnant women, since the pregnant metabolic condition is not being taken into account.

Only 30 percent of women with an abnormal glucose tolerance test will have larger-than-average babies. It is just as easy, however, to predict the likelihood of a large baby by assessing prepregnant weight, weight gain during pregnancy, and gestational age.¹ In fact, most large babies will be born to mothers with normal glucose tests. The glucose tolerance tests themselves are unreliable and can be duplicated only 30 to 50 percent of the time.²

No controlled studies have proven that high blood sugar leads to problematic or high-risk pregnancy. In fact, one clinical trial, which studied the outcomes of women who had elective cesarean sections because of gestational diabetes, showed a significantly higher incidence of mortality for the babies, with no better outcomes than the control group.³ Further, Murray Enkin, MD, and his colleagues, who compiled data from 9,000 controlled trials from 400 medical journals in 18 different languages for the Cochrane Database, found that labeling patients "high-risk" due to gestational diabetes subjected them to many expensive and time-consuming tests and interventions that have no proven benefits.⁴

Gestational diabetes should not be confused with a preexisting diabetic condition. Women who have been diagnosed with some variation of diabetes prior to pregnancy, or who have a family history of diabetes, are obese, or who have previously delivered a baby that weighed more than nine pounds,⁵ are more likely to have true glucose intolerance during pregnancy. They may require close monitoring throughout their pregnancies to prevent stillbirth and congenital defects.

Testing for Group B Streptococcus (GBS)
Unlike the bacteria that causes strep throat, GBS causes blood and skin infections and pneumonia. In pregnant women, GBS can cause bladder and womb infections and stillbirth. Before prevention methods began to be used, about 8,000 babies in the US contracted GBS infections every year, and about 5 percent would die. Between 5 and 35 percent of pregnant women temporarily carry GBS in their bodies, often in the vagina or rectum, although they do not develop symptoms. When a baby moves down the birth canal, it can become infected by the bacteria, which can lead within a few hours to pneumonia, sepsis (infections of the blood or tissues), or meningitis. As infants don't handle infection well, the disease can spread quickly, and some can die before it is even detected.

It is now routine practice to test pregnant women for the presence of GBS in late pregnancy, around week 37. This is done by swabbing the rectum and vagina. A culture then takes a few days to give results.

A positive test (indicating that you have GBS) does not necessarily mean that you will transmit it to your baby. Actual transmission of GBS involves other risk factors, including:

• The presence of fever during labor
• A urinary-tract infection due to GBS
• Rupture of membranes (water breaking) 18 hours or more prior to delivery
• Rupture of membranes prior to week 37
• A previous baby with GBS

If you test positive for GBS, antibiotics will be offered to you intravenously during labor. Taking a course of antibiotics prior to labor, however, does not protect the baby. If you decide to have intravenous antibiotic treatment, ask for a heparin lock on your intravenous line, which allows it to be unhooked so you have freedom to get up and move around during labor.

Testing for Preeclampsia
Preeclampsia, also called toxemia, is a condition that affects 5 to 10 percent of pregnancies, usually in the third trimester.⁶ Preeclampsia is pregnancy-induced hypertension characterized by elevated blood pressure, excessive retention of fluids, especially in the hands and face, rapid weight gain, double or blurred vision, growth retardation in the fetus, and protein in the urine. Having any of these symptoms may not necessarily indicate preeclampsia, however. As well, some women with preeclampsia have no symptoms at all other than a feeling that "something is not right."

No one knows what causes preeclampsia. You are more likely to have it if you have diabetes, are less than five feet three inches in height, or have had a previous history of high blood pressure. New research indicates that a previous history of preeclampsia in either the mother's or the father's family is a risk factor. The risk is also higher for first-time pregnancies and for women who have new partners for their second pregnancies. This suggests an immunologic contribution that is, as of yet, not well understood. It is also thought that nutrition may play a part in preeclampsia.

If left untreated, preeclampsia can develop into the more severe eclampsia, characterized by convulsions, coma, and even maternal or fetal death. This condition is quite rare, because most women receive treatment before it reaches this stage. In the more severe stages, symptoms can include abdominal pain, severe headaches, nausea, vomiting, and convulsions. Left untreated, failure of the placenta can occur, causing premature labor.

Preeclampsia is usually diagnosed during routine urine examinations that screen for high levels of protein. If it is determined that you have preeclampsia, you may be advised to get bed rest for most of the rest of your pregnancy, either at home or in a hospital. There is not, as of yet, conclusive evidence that complete bed rest is helpful for women with mild to moderate preeclampsia,⁷ and it is not an easy thing to do. You will need to decide if this is right for you. You will most likely be given antihypertensive medication to keep your blood pressure down. Diuretics were commonly given in the past to treat preeclampsia, but are now generally thought to be effective only in reducing the symptom of water retention. Diuretics will not prevent preeclampsia's potential negative effects on the baby.

Promising recent studies suggest that using fish oils, evening primrose oil, and calcium in early pregnancy may help prevent preeclampsia.⁸ For many women, increasing their protein intake will reduce the symptoms of preeclampsia.

Testing for Rhesus Incompatibility
Rhesus incompatibility occurs when the mother's blood is Rh-negative and the fetus has inherited Rh-positive blood from the father.

If fetal blood enters the mother's bloodstream (for example, during delivery, miscarriage, abortion, amniocentesis, or fetal blood sampling), her body will produce antibodies to fight it. Although this condition rarely presents a problem in the first pregnancy, the antibodies remain in the mother's blood, and in subsequent pregnancies may attempt to destroy the blood supply of the new fetus. This can result in severe anemia, jaundice, brain damage, or death to the baby.

Your blood will be tested in early pregnancy to see if you are Rh-negative. If you are Rh-negative and your partner is Rh-positive, you will be tested frequently throughout pregnancy to see if you have developed any antibodies. During your third trimester or soon after delivery, you will be given a vaccine (known as Rhogam) to prevent antibodies from developing and endangering future pregnancies.

In the past, Rhogam, like many vaccines, contained a preservative known as thimerosal, or mercury. The safety of this is now being questioned, and the use of mercury is being phased out.

NOTES
1. Murray Enkin et al., A Guide to Effective Care in Pregnancy and Childbirth (New York: Oxford University Press, 2000), 104.
2. Ibid.
3. Ibid.
4. Ibid., 77.
5. William Sears and Martha Sears, The Birth Book (New York: Little, Brown and Company, 1994), 97.
6. Sheila Kitzinger, The Complete Book of Pregnancy and Childbirth (New York: Knopf, 1996), 139.
7. Enkin et al., A Guide to Effective Care, 123-124.
8. Ibid., 122-123.