Prenatal blood screening provides the base for a healthy pregnancy. It is a vital tool that ensures a safe pregnancy and a healthy child. Once the pregnancy is confirmed, doctors usually advice certain routine blood tests. These tests help determine the blood type and Rh factor – positive or negative and reveal the presence of any infection. Moreover, it also runs a check on the presence of any risk that might show up complications later in pregnancy.

Blood type and the Rh factor:
Besides the four basic blood types A, B, AB and O, the Rh factor plays a major role in healthy pregnancy. If the mother’s blood type, particularly the Rh factor, is different from that of the baby, the mother’s immune system starts producing antibodies might react to the baby's blood, destroying its red blood cells.

Though, rarely a problem in the first pregnancy, antibodies created during the first pregnancy can threaten subsequent pregnancies causing severe problems to the unborn child, including foetal anemia, heart failure or even death.

However, these complications can be prevented by administering an unsensitised Rh-negative mother with two doses of Rh immune globulin, one at 28 weeks of pregnancy and the other within 72 hours of delivery.

Sexually transmitted disease
Exposure to certain sexually transmitted diseases like HIV can be revealed by prenatal blood screening. Also, the VDRL test checks for the presence of syphilis. Untreated syphilis is known to cause stillbirth or neurological damage to the child.

Anemia

A hemoglobin test gauges the level of red blood cells in the body. Few red blood cells reveal the presence of anemia. As red blood cells are the carrier of oxygen to all body tissues as well as to those of the foetus, severe complications may arise if not treated. The most common anemia is iron deficiency and can be corrected by taking iron supplements.

Hepatitis Test
An infectious disease that can damage the liver, pregnant women with Hepatitis B antigen may transmit the infection to their infants.

The blood screening checks if the mother is a carrier of Hepatitis B antigen. If so, the baby can be vaccinated with the Hepatitis immunoglobulin and Hepatitis B vaccines just after birth to protect against infection.

Chickenpox and Rubella
Blood tests help to determine if the mother is completely immunized for chickenpox and rubella.

As one cannot be immunized against chickenpox and rubella once pregnant, it is ideal to go in for the blood screening before planning the pregnancy. Once vaccinated, health experts’ advice to wait for three months before trying to conceive again.