First trimester of pregnancy

Fetal development during the first trimester

The most dramatic changes and development occur during the first trimester. During the first eight weeks, a fetus is called an embryo. The embryo develops rapidly and by the end of the first trimester it becomes a fetus that is fully formed, weighing about .5 to one ounce and measuring, on average, three to four inches in length.

Know your blood type

All pregnant women are tested for the Rh factor during the early weeks of pregnancy. A mother and fetus may have incompatible blood types; the most common is Rh incompatibility. Rh incompatibility occurs when the mother's blood is Rh-negative and the father's blood is Rh-positive and the fetus' blood is Rh-positive. The mother may produce antibodies against the Rh-positive fetus, which may lead to anemia in the fetus. Incompatibility problems are monitored and appropriate medical treatment is available to prevent the formation of Rh antibodies during pregnancy.

The first prenatal visit

Your first prenatal visit is the most thorough. A complete medical history is taken, a physical examination is conducted, as well as certain tests and procedures are performed to assess the initial health of the mother and the embryo. The first prenatal visit may include:

Personal medical history - this may include taking record of any of the following:

• previous and current medical conditions - such as diabetes, high blood pressure (hypertension), anemia, and/or allergies
• current medications - prescription and over-the-counter
• previous surgeries

Maternal and paternal family medical history - including illnesses such as diabetes or mental retardation, and genetic disorders such as sickle-cell disease or Tay-Sachs disease.

• personal gynecological and obstetrical history, including past pregnancies, and menstrual history (such as length and duration of menstrual periods).
• education - including a discussion regarding the importance of proper nutrition, regular exercise, the avoidance of alcohol, drugs, and tobacco during pregnancy, and a discussion of any concerns about domestic violence.
• pelvic examination - this type of examination may be performed for one/all of the following reasons:
• laboratory tests - including:
  • urine tests - to screen for bacteria, sugar, and protein
  • blood tests - to determine blood type
  • blood-screening tests - to detect diseases (such as rubella, also called German measles)
  • genetic tests - to detect inherited diseases (such as sickle-cell anemia, Tay-Sachs disease)
  • screening tests - to detect infectious diseases (such as sexually transmitted diseases)

The first prenatal visit is also an opportunity to ask any questions or discuss any concerns that you may have about your pregnancy.