Complete Blood Count
This blood test checks for anemia – low red blood cell count. Because of the increase in the volume of blood that a pregnant woman must have as part of her normal physiology in the first trimester, production of red blood cells is very important. Some women are unable to produce all the red cells they need, resulting in anemia that shows up over time. We also use the complete blood count to identify whether a woman has normal levels of platelets (the building block that is used in clotting).
Glucose Tolerance Test
Pregnant women will often have elevated glucose in their blood circulation due to all the hormones produced by the placenta. Hormones force the mother’s body to circulate nutrition (fats, proteins and sugars) for the fetus can to pull across the placenta to its circulation. If the mother has a slight tendency towards diabetes, these placental hormones can result in elevated sugars or “glucose level.” This in turn can result in a baby that is unusually bigger or heavier and perhaps more difficult to deliver and at risk for getting stuck in labor.
To identify pregnant women who might be at higher risk for this elevated glucose level, a glucose tolerance test is performed which essentially asks, “How does mom handle an extra sugar load?” A syrup drink containing 50 grams of glucose is given and the glucose level in the mother’s blood is tested an hour later to see if she is able to clear the extra glucose from her blood stream. Women who have levels over 140 are then administered a diagnostic test involving a larger amount of sugar syrup. Four different blood levels are drawn prior to taking the sugar, and then again one hour, two hours and three hours after taking the syrup. A pregnant woman who has elevated levels in this three-hour test is considered to have gestational diabetes. Most often the elevated sugars can be treated with appropriate changes in diet, in consultation with a nutritionist. In some cases, hanges in diet are not able to bring the glucose levels down adequately, and insulin becomes necessary for the rest of the pregnancy.
In women who have the blood type called Negative (such as O Negative, A Negative or B Negative), their red blood cells do not carry the Rh factor on their surface. The Rh factor is a very strong stimulator of immune antibody response in someone who is Rh Negative. If an Rh Positive cell gets into a person who is Rh Negative, they will mount an immune response that will become very strong, especially with repeated introductions of the Rh positive factor. This response could be strong enough to cross a placenta and attack and destroy the red cells of an Rh Positive fetus.
To prevent an Rh Negative mother from developing an immune response (determined by testing for the presence of antibody) to Rh Positive blood, a Rhogam shot is given at about 28 weeks and again after birth. The Rhogam block off the response to any fetal red cells that will have traveled across the placenta in the third trimester or during labor. This also prevents the mother from ever having a strong enough immune response that might harm future pregnancies.
Group B Strep
At 36 weeks we administer the Group B strep (GBS) test to screen for Group B Streptococcus. Group B strep is normal bacterial that lives in the vagina of some women and does not usually cause infections.
However, newborn babies can develop severe infections from GBS, which they get passing through the birth canal.
To test if the bacteria is present, a sample from the lower part of the vagina and the rectum is taken with swaps. Bacteria from the swaps are grown in a culture to see if GBS is present. Women who have a positive culture will be treated with antibiotics during labor to prevent the baby from getting GBS.