Pregnant women undergo many tests during pregnancy, often without fully understanding the reasons for the tests. Some tests, done at every prenatal visit, seem so routine that their importance is often lost on mothers-to-be. While waiting to see the medical practitioner each month or so may seem like a waste of time when she spends only a few minutes in the room, valuable information is received from simple blood tests and other monitoring. Identifying abnormal test results early often prevents complications that can harm mother and fetus.
Glucose Challenge Screening
Gestational diabetes, a form of diabetes that occurs in pregnancy, can cause serious problems in the developing fetus before, during and after birth. Glucose challenge screening, normally done between 26 and 28 weeks of pregnancy, involves drinking a solution containing 50 grams of glucose, or sugar. An hour later, a blood test records the amount of glucose in the blood. Blood glucose levels normally peak after one hour. Levels higher than 130 to 140 milligrams per deciliter, or mg/dl, may indicate gestational diabetes and require further testing.
Glucose Tolerance Test
Elevated glucose challenge test levels require follow-up with a three hour glucose tolerance test. The three-hour GTT requires fasting overnight. Fasting blood glucose is drawn, followed by consumption of a concentrated glucose drink . Blood is drawn at one, two and three hours after drinking the liquid. Levels over 95 mg/dl while fasting, or higher than 180 mg/dl at one hour, 155 mg/dl at two hours and 140 mg/dl at three hours are considered abnormal. Women with abnormal GTTs may have gestational diabetes and require frequent monitoring of blood glucose levels . Some need insulin injections in pregnancy. Babies born to diabetic mothers, who may be larger than normal, often have trouble during birth due to size and may have low blood sugar levels after delivery.
Group B Streptococcus
Group B streptococcus, or GBS, is a bacteria that 10 to 30 percent of pregnant women carry in the vagina or rectum; it may cause no problems to them but can infect and sicken their newborn. Pregnant women are tested for GBS around 35 to 37 weeks of pregnancy via vaginal and rectal swabs and treated with intravenous antibiotics during labor if found to have the infection. Around 5 percent of babies who contract GBS during the birth process die, so women who haven’t had GBS testing receive antibiotics routinely during labor.
Urine Tests
At each prenatal visit, urine tests check for protein, bacteria and other abnormalities in the urine. Up to 10 percent of pregnant women have bacteria in their urine, even though they have no symptoms, the March of Dimes states. Bacteria in the urine can cause kidney infection or preterm labor in some cases. Protein in the urine can indicate pre-eclampsia, also known as pregnancy-induced hypertension, a serious complication of pregnancy. Sugar in the urine may indicate diabetes.
