First Trimester Tests

Tests Performed During the First Trimester

The partnership you will develop with your doctor or nurse-midwife during your pregnancy will be of the utmost importance. To become an active participant in your own care you should consult with your health care provider about which tests are appropriate for needs and family history. Below is information on tests that may be used.

Vaginal Examination

These exams are performed for the following reasons during early pregnancy:

  • Confirming pregnancy
  • Correlating the size of the uterus with the date of the last menstrual period
  • Estimating the size and shape of the pelvis
  • Obtaining vaginal secretions to detect infection or cervical cancer (Pap smear)

Vaginal exams may be performed toward the end of pregnancy for the following reasons:

  • Assessing effacement and dilation of the cervix
  • Determining the station of the baby
  • Obtaining vaginal secretions to detect infections

At times, vaginal exams can be uncomfortable, and may cause a reddish or dark-brown vaginal discharge.

Urine Tests

At each prenatal visit, it is necessary to test urine in order to:

  • Detect infection
  • Check for sugar and ketones, potential indicatoes of diabetes
  • Check for protein, which may indicate infection or pre-eclampsia.

Blood Tests

Blood may be drawn during the 1st or 2nd prenatal appointment, for the purposes of:

  • Confirming pregnancy (1st visit)
  • Testing for anemia
  • Determining your blood type
  • Testing for antibodies to HIV and AIDS virus
  • Determining your Rh type
  • Testing for syphilis
  • Testing for German measles immunity
  • Testing for antibodies to Hepatitis-B virus

Checking Blood Pressure

In order to detect pre-eclampsia or pregnancy induced hypertension (PIH), your blood pressure will be checked at every office visit.

Checking Your Weight

Sudden weight gains are potential indicators of pre-eclampsia, and checking your weight at every prenatal office visit is a method of monitoring general nutritional health.

Abdominal Exam

Your abdomen will be examined at each prenatal visit to measure the growth of the uterus which indicates fetal growth and gestational age. In the last weeks of pregnancy, it will also give your doctor or nurse-midwife important information about the size and position of the baby.

Checking Fetal Heart Rate

Utilizing a handheld ultrasound device called a Doppler, the baby's heart-rate is checked during every prenatal office visit to assess the well-being of the baby.

Breast Examination

Breasts are examined to detect any abnormalities that would warrant further examination. For example, nipples are checked to see if they are flat or inverted, to ensure successful breastfeeding later.

Additional Tests (Non-Routine)

The following diagnostic tests may be ordered by your doctor or nurse-midwife in order to evaluate the health of mom and baby. They are not routinely performed on every pregnant woman. For example, if a woman is over 35 years of age, an amniocentesis may be recommended. Screening tests like this can indicate an increased risk for a genetic problem.


This procedure is usually performed after 15 to 20 weeks of gestation. A needle is inserted through the mother's abdomen (and uterus) to obtain a sample of fluid from the amniotic sac. Testing the amniotic fluid provides information on certain metabolic disorders, birth defects, or chromosomal abnormalities such as Down syndrome, sickle cell anemia, and many others.

Though it may sound painful, amniocentesis is ually a gentle, fairly comfortable procedure.

Chorionic Villus Sampling (CVS)

Testing the chorionic villi can provide information about genetic defects and chromosomal abnormalities. If ordered, the CVS procedure is usually performed between 10 and 12-weeks of gestation. A catheter is inserted into the uterus through the opening in the cervix (transcervical CVS) or through the abdominal wall via a needle (transabdominal CVS) to obtain a sample of chorionic villi, which are finger-like wisps of placental tissue.

CVS is not a painful procedure.

As with amniocentesis, there is concern that having the CVS test may cause a woman to miscarry. The likelihood of miscarriage due to CVS is not known with certainty. About 4% of women who have had CVS have had a miscarriage following the test, though it is unclear which of the miscarriages were actually due to the test, as it is generally believed that many miscarriages occur spontaneously. Several studies suggest that CVS has about a 0.5-1.0% greater risk than amniocentesis for causing a miscarriage. To some patients, having the CVS performed during the first 3-months of pregnancy (& getting the results quickly) is considered an advantage, so they are willing to assume a slightly higher-risk, as opposed to waiting for an amniocentesis. There is also a small but important risk of infection in the uterus following CVS. Following your CVS, you should be given an instruction sheet about how to watch for possible infections and other complications of the test.

Important note: Talk with your doctor or nurse-midwife regarding the benefits versus the risks.

First Trimester Screens and Tests


Ultrasound: A transducer that sends sound waves is placed on your abdomen or in your vagina to form a picture of your baby on a screen.

Why It May Be Offered

If your dates are uncertain or if you have a high-risk medical condition, this test may be done to measure your baby's growth.

Chorionic villus sampling (CVS): A small amount of tissue is removed from your baby's developing placenta under careful ultrasound guidance by a specialized doctor. This is done with a catheter (in your vagina) or a needle (in your abdomen), depending on your placenta's location. Your baby's cells are grown in culture and the chromosomes are studied.

To women age 35 or older to check for chromosomal disorders (such as Down syndrome). Or to those identified at risk for specific genetic disorders where a test exists.

Cultures: They are taken in order to detect sexually transmitted diseases.

So you can be treated and your baby will not be at risk.

Cystic fibrosis carrier test: This blood test or cheek swab will determine if you and/or your partner have a single dose of an altered gene for cystic fibrosis. Not all carriers are identified.

To determine if you are at risk for having a baby who will have cystic fibrosis.

Pap smear: A swab collects cervical cells which are then viewed under a microscope.

A regular screening test most women have annually or at the beginning of pregnancy to detect abnormal cells or signs of cervical cancer.

Prenatal profile: Blood is drawn from your arm to screen for blood type, antibody information and diseases.

A test given often to rule out possible complications; given to most pregnant women by their health care providers as a standard screening.

First Trimester Screen: A new, optional noninvasive evaluation that combines a maternal blood screening test with an ultrasound evaluation of the fetus.

To identify risk for specific chromosomal abnormalities. Additional information on first trimester screens