DNA Testing In Pregnancy - What You Need To Know

By: Lynn Pattimakiel, MD • Posted on February 22, 2016

Pregnancy Risks After Age 35

Like many other working women today, I found my prince charming later in life. My husband, Mark, was definitely worth the wait!

Mark and I always knew that we wanted to have children but felt the urgency of the dreaded biological clock. We were both aware of the stigma associated with having children over the age of 35.

Were we going to have difficulty conceiving? Was our child going to be at high risk for health problems?

When I first found out I was pregnant, I was incredibly excited but also in disbelief. The whole experience felt surreal. Funny enough, even though I work in the medical field, I managed to keep messing up my pregnancy tests. How hard could this be? You just pee on the stick, right?

Although otherwise completely healthy, being over 35 landed me in the “high risk” category. This definitely can be an unsettling place to be. I quickly realized that it didn’t mean that my baby was guaranteed to have a health problem, but that I would benefit from more frequent monitoring, and qualified for some extra testing. With all this extra attention, I decided to think of this status as being taken care of as a VIP!

When a Pregnancy is Considered High Risk

Other conditions that may put you in the high risk category include chronic medical conditions such as:

Diabetes
High blood pressure
Seizures
Heart disease
Active smokers
Multiple gestational births
Personal or family history of chromosome abnormality
Infections
Certain medications

On the first meeting with my obstetrician, I was counseled on my personal risks based on my medical history and family history. We discussed the importance of regular visits to monitor for conditions such as:

Preeclampsia
Placental problems
Gestational diabetes

Screening Tests During Pregnancy

My obstetrician also discussed my options for screening tests.

Sequential Screening

The first available testing is called sequential screening. This combines an ultrasound and blood testing to determine the risk of some fetal chromosome abnormalities and birth defects.

Ultrasounds

During the first trimester, I had an ultrasound to measure the nuchal translucency.

This is a measurement of the fluid filled space behind the neck, which is often increased in size in certain chromosomal abnormalities.

(This detects approximately 90-92% of fetuses with down syndrome and 90% of fetuses with Trisomy 18. There may be a false positive rate of 5%.)

The first time I heard my baby's heart beat brought a flood of relief and joy. The first time I saw her on the ultrasound I felt truly amazed by the miracle of life. Even though she was so small I could identify her head and her little nose. She was really moving around in there!

Blood Work

I also had my blood work drawn between weeks 15-21 to screen for open neural tube defects.

New Blood Test for Chromosomal Abnormalities

I was surprised to learn about a new advancement in testing for chromosomal abnormalities called Non-Invasive Prenatal Testing (NIPT) or MaterniT21. This test is offered to the following:

Women who are at higher risk.
Women who had an abnormal screening test.
Women who had an abnormal ultrasound finding.

What is Non-Invasive Prenatal Testing (NIPT)?

NIPT is performed through a simple maternal blood test and detects a small amount of circulating fetal DNA which can be analyzed for abnormalities. This test can be completed as early as 10 weeks gestation. It is sent to an outside lab for processing and the wait time for results is 7 days.

It identifies chromosomal abnormalities such as the following at a higher accuracy then the sequential screening alone:

Down syndrome
Edwards syndrome
Patau syndrome
Turner syndrome
Klinefelter syndrome
Triple X syndrome

This testing can detect approximately 99% of fetuses with Down’s syndrome and trisomy 18. False positive results are rare. Although a great advancement, it does not detect all chromosomal abnormalities. This testing is not covered by all insurances, so make sure to have the discussion with your physician before completing the test.

Benefits of NIPT Compared to Amniocentesis

NIPT is less risky than sampling through amniocentesis. Amniocentesis is testing of the amniotic fluid from the amniotic sac which surrounds the fetus. This invasive procedure may carry the rare risk of miscarriage.

If the NIPT testing is positive, confirmation is recommended with either chorionic villus sampling or amniocentesis.

Another benefit of the NIPT testing is that we were able to find out the sex of our baby as early as 10 weeks, instead of waiting for the standard ultrasound that is completed between 18-20 weeks, which evaluates gestational age and fetal anatomy.

The decision to screen for chromosomal abnormalities is a personal choice, but I viewed it as having extra information to help best prepare me for the arrival of my baby.

I feel although still labeled as high risk, the perks of having a baby at this time of my life are numerous. I feel more grounded, financially secure and hopefully have gained some maturity and wisdom to help handle the exciting adventure being delivered our way. Being a more mature, married woman and expecting the miracle of birth was definitely worth the wait!

Be Strong. Be Healthy. Be in Charge!

-Lynn Pattimakiel MD

pregnancy, high risk pregnancy, fertility, women's health, women, dr. lynn pattimakiel

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