Prenatal Testing in the First Trimester: What and Why?

Prenatal testing will go on throughout your pregnancy. Most tests are routine and not uncomfortable, and they will give your obstetrician a lot of valuable information regarding your health and the health of your baby. The intention of most of these prenatal tests is to confirm that everything is just fine, but they also aim to identify any complications that may be developing. The first trimester of pregnancy is a time of important development for your baby. Your OBGYN will want to make sure that everything is moving along exactly as it should.

Initial Bloodwork

The first round of prenatal bloodwork will check to make sure you are in good health, and it will look for conditions that could affect your pregnancy. Your blood type will be checked, and your OBGYN will make sure you don’t have anemia. Your obstetrician will also check your Rh factor, a protein in the blood cells. If you are Rh-negative and your fetus is Rh-positive, this can lead to incompatibility problems, which your doctor will want to prevent.

This initial bloodwork will also check for conditions such as syphilis, Hepatitis B, and HIV and will check your immunity for German measles.

Urine Test

You will have a urine test at your first prenatal visit and probably at every subsequent visit as well. In early pregnancy, your urine can be tested for the hCG level, which will confirm you are pregnant. Your OBGYN will also look for signs of kidney infection, glucose or albumin to identify possible problems with gestational diabetes or high blood pressure. Your urine will continue to be monitored for abnormalities throughout your pregnancy.

Do You Want Genetic Testing?

As the first trimester approaches its completion, your obstetrician may ask you if you want genetic testing. These tests are not 100% accurate but may give information on whether your baby is at risk for certain congenital conditions.

You may prefer to decline this and just let the pregnancy run its course rather than going through the stress of trying to detect possible problems. If you do decide to go through with genetic testing, you should discuss all the options and possible complications with your doctor.

Non-Invasive Tests

Some genetic tests are non-invasive and work like a specialized ultrasound. One or more of these tests may be offered to you, particularly if you are over 35. Non-invasive tests don’t pose any risk to you or the fetus. They screen for chromosomal abnormalities such as spina bifida and Down syndrome. If abnormalities are detected, further testing may be recommended, because screening tests don’t actually diagnose. An abnormal result on a screening test sometimes proves to be false.

Amniocentesis or CVS

Amniocentesis and chorionic villus sampling (CVS) are examples of tests that are more invasive. They take samples of the amniotic fluid or placenta to more accurately diagnose genetic abnormalities or genetic defects such as sickle cell anemia, cystic fibrosis, muscular dystrophy or Down syndrome. CVS is performed during the first trimester and amniocentesis would be done during the second trimester. A genetic counselor may be able to help you decide if you want to go through with one of these tests.

Ultrasound

Early in pregnancy an ultrasound can be useful to confirm viability and get accurate dating. If you are unclear when your last period was, an ultrasound can be performed as early as 6-7weeks of pregnancy to estimate your due date. Or your obstetrician may wait until the second trimester to do this non-invasive diagnostic test. You will most likely have an additional ultrasound in each of your second and third trimesters to monitor fetal development and screen for any potential problems.

When Should You Schedule Your First Test?

Some prenatal labs will be drawn on your first pregnancy-related visit to your OBGYN. Urine samples will also be taken each visit thereafter in order to measure things like your protein and glucose levels. 

In general, you’ll want to schedule a visit with your OBGYN as soon as you think you might be pregnant, and these initial screenings are a big reason why. The data gathered will provide both a useful baseline and an early indicator for your baby’s health. You and your OBGYN will then discuss a schedule for further testing. Usually, the first trimester testing schedule looks something like this:

• Initial Visit: Blood and urine screenings Often we perform ultrasound with the initial visit to validate dating or establish viability/dating.
• Between weeks 6-12: First Trimester Ultrasound
• Between Weeks 10-12: CVS and other genetic screenings (as noted, these genetic tests are considered optional).Often a second ultrasound performed her for assessing nuchal translucency which is also a part of genetics so you could just leave as is. 

Based on your individual needs, there may be other screenings or diagnostics your OBGYN will want to incorporate into your schedule. You’ll talk to your OBGYN about the value and benefit of each of these screenings and then decide on an appropriate and timely course of action. The goal of prenatal testing is to monitor the health of your baby and provide you with peace of mind that everything is progressing normally.

What Happens if You Miss Your First Trimester Testing?

If you do not have access to prenatal testing during your first trimester, it’s important to talk to your OBGYN about what your options may be. Some first trimester tests may simply be moved to “as early as possible” in the schedule order. For example, blood tests and ultrasounds are common throughout your pregnancy. 

Other tests and screenings may also be combined for your convenience, but you’ll want to talk to your OBGYN about specifics for your situation.

First trimester prenatal tests are very important, but you shouldn’t panic if unavoidable circumstances have caused you to miss them. The goal is simply to get your testing back on track as quickly as possible.

Are There Risks to Screenings?

Ultrasounds, blood work, and urine screenings pose absolutely no risk to you or to your fetus. They are completely routine. You also don’t need to do anything special to prepare: you can eat and drink normally (unless instructed to do otherwise by your OBGYN). As mentioned earlier, one risk to genetic screening is that it could be a false positive screen that leads to further testing and sometimes more invasive diagnostic procedures. Ultimately this could cause more stress and worry.

The Importance of Prenatal Testing

First trimester prenatal testing is designed to provide information to parents as early in the pregnancy as possible. Screenings can detect problems early and, often, therapies can be deployed to help ensure a healthy and productive pregnancy. The goal of your OBGYN will be to monitor your health and the health of your growing baby.

The point of optional genetic screenings, on the other hand, is to provide parents with time: If the tests reveal nothing to worry about, you’ll have more time to enjoy your pregnancy without some specific anxieties hanging over your head. 

On the other hand, if genetic screenings reveal a cause for concern, you will have more time to consider your options and plan accordingly. For example, you may wish to schedule further screenings, depending on the results of your first trimester screenings.

All your testing options should be discussed with your OBGYN so that you understand what tests are being run and why.

If you’d like to see a gynecologist at NSAGO, please contact us at our Wilmette or Glenview locations.