Genetic screening

One question that frequently comes up in my office is whether my pregnant patients should have genetic screening.  This is a really complex issue, and it's also very personal.  I usually lay out the pros and cons of testing, and help my patients decide for themselves whether to have the tests.

First of all, genetic screening should be an optional test.  I don't recommend across the board that all patients have it.  It's important to know what is being tested, and what you will do with that information once the test is completed.

Genetic screening is a way to decide which pregnant patients are at high risk of having a child with chromosome problems, such as Down Syndrome (an extra copy of chromosome 21) or other more serious trisomies (extra copy of either chromosome 13 or 18).  The test is not diagnostic, meaning it does not tell you whether your baby has a chromosome problem or not.  When the results of the test come back, they say something like "positive screen for trisomy 21, risk 1:100".  A positive screen is an arbitrary cutoff point, usually if the risk is greater than that of an average 35 year old woman.  As you can imagine, a positive screen can cause significant anxiety, but since it is a screening test only, there is a high false positive rate, and a diagnostic test such as amniocentesis or chorionic villus sampling is the only way of knowing for sure if your baby is affected.  I think it is important for women to decide ahead of time what they would do if they had a positive screen.  If an amniocentesis is completely out of the question, they may not want to have the screen.  Likewise a negative screen does not completely rule out chromosome problems.  If a woman is at particularly high risk of chromosome problems, such as a history of an affected infant, she may want to skip the screening altogether, and go straight to diagnostic testing.

There are several ways to screen for trisomies.  The earliest results come from what's called "First Trimester Screening".  This involves an ultrasound of the back of the baby's neck, called Nuchal Translucency or NT, between 11 weeks and 13 weeks 6 days gestation, as well as a blood test on the mother to check the levels of specific proteins, PAPP-A and free beta-hCG.

In the second trimester, between 15 and 22 weeks, the Quad test is offered.  This involves checking the mother's blood for 4 different proteins, total hCG, AFP, unconjugated estriol, and Inhibin-A.  There is no ultrasound with the second trimester screen.  This test also provides a screen for open neural tube defects such as spina bifida and anencephaly, where the brain and/or spinal column do not close completely during development.

These tests can be done individually, sequentially, or integrated (confusing, I know).  A large study published in the New England Journal of Medicine in 2005, called the FASTER trial, showed that for a set 5% false positive rate, the detection of Down syndrome was highest, 96%, if the patient had fully integrated screening.  This means the first trimester screen with ultrasound and blood test and the second trimester Quad test were done, and all the results were integrated to give a risk.  Sequential testing refers to the same tests, but results are given after each test is completed, instead of waiting until after the Quad test to integrate the results.

So, if you're still confused, what does this mean?  Bottom line, think about first of all, whether this information is important to you.  Do you want to find out before you have your baby if there are any chromosome problems?  What would you do differently if you found out your baby had a trisomy?  For some women, if they know they will have a baby who has a potentially lethal defect, they would opt to terminate the pregnancy.  For other women, termination would never be an option.  Others may want to know just to be prepared for what will happen when the child is born.  Some women are comfortable not having this information, and would not want to know ahead of time.

The one genetic screen that most women do have during pregnancy is a detailed anatomic ultrasound sometime around 20 weeks of gestation.  Although it can not diagnose genetic problems, major anatomic defects can raise suspicion for chromosome issues and diagnostic testing could be performed then.  There is also a chance that the ultrasound would look totally normal, but the baby has Down syndrome or other chromosome problems.

It's a lot to think about.  With new developments in what we can find out prior to delivery, more complex decisions have to be made.  There are a lot of ethical issues also involved in the discussion.  I believe every person has the right to make an informed decision about what testing they do or do not desire during pregnancy.  I welcome comments or questions related to this topic...

"The Talk"

I have a 10-year-old daughter and last year, in the 4th grade, she brought home a paper from school stating that they would be learning about puberty the following week.   I knew that I needed to talk to her about this before she heard it at school.

Now, I talk to people about this kind of stuff every day, but it is really different to reveal the mysteries of the universe to your child.  We've discussed bits and pieces of this topic over the years, usually in vague terms.  I still remember, though, how my daughter (then age 6) explained to my son (then age 3) while they were riding in the back of my minivan how "babies come out of a woman's vagina...and if it can't come out that way, they have to have a C-section."  My son just said "oh" and started talking about the new topic already on his mind.

But now it was time to get into a little more detail, and this time it was more specifically directed at what would be happening to HER.  Although I am obviously able to speak about these matters in clear scientific terms without feeling embarassed,  I still felt like somehow I would be taking her childhood away by discussing these adult topics.

I wracked my brain trying to figure out how to bring up the topic, and how much information should be given.  I even took an informal poll of my friends who have kids the same age to hear how they brought it up and what exactly needed to be said.  Finally, I settled on buying the book "The Care and Keeping of You", part of the American Girl series, which deals with puberty as well as general hygiene and personal care issues.  As anyone with a 10-year-old knows, personal hygiene isn't always at the top of the priority list, so I thought it would be good to review that as well.

We sat down together on a Friday night, and skimmed through the book.  I explained things, using the pictures in the book to illustrate my points.  To my amazement, she handled the discussion with a lot of maturity, and asked very appropriate questions.  It was even sort of a bonding moment for us, as corny as that may seem...

We still haven't covered the "ins-and-outs" of sex (pardon the pun), but I know that's an important topic for parents to discuss with their kids.  My daughter can handle it, I just need to take baby steps...I need to come to grips with having my kid grow up:)

This week, I ran across an article in the Wall Street Journal about how we parents should share this information with our kids from the time they start to speak, and answer their questions as they come.  It takes away the awkwardness of the situation, and makes sex and sexuality a normal part of everyday life.  I couldn't agree more.  A link to the article is here:  http://online.wsj.com/article/SB10001424052970204358004577032421571545382.html

One thing I've learned is that parenting isn't always easy, and most of the time you don't know what the heck you're doing.  I also know that kids can handle a lot more than we give them credit for.

World Prematurity Day

My niece, the day after she was born.  10 inches long, 1 lb 2 oz

Me holding her at about 2 months of age. 

About 1 month old... 

My nephew the day he was born.

About 6 weeks old.

Me holding my nephew, about 6 weeks old.

November is Prematurity Awareness month, so I thought I would start this blog with an issue that is very close to my heart.

In 2004, my sister was expecting her first baby in October.  Everything was going perfect until one early morning in June when bleeding and contractions began.  My niece was born later that day at 24 weeks of gestation, weighing only 1 pound 2 ounces, despite valiant efforts to stop the preterm labor.  It was a horrendous experience to watch my sister and her husband face.  None of us knew whether their baby would even live, and then what disabilities she may face if she did live.  With the prayers of many friends and family members, and a wonderful team of physicians and nurses in the NICU, after 110 days in the hospital, she came home.  She is now a healthy 7-year-old.  The following year, we re-lived the experience when my sister had her second child, my nephew, at 27 weeks gestation.  He fought the odds as well, and is a rambunctious 6-year-old today.  No specific cause was determined for why this happened to her.  Although we are so grateful for the outcome, we know that it doesn't always end this well.  I have delivered many premature babies and it is heartbreaking to watch the emotional rollercoaster that their families go through.

In the United States, 1 in 8 babies are born too early (less than 37 weeks gestation, or more than 3 weeks too soon).  Worldwide, there are 13 million babies born prematurely each year.  Prematurity is the number one cause of death for newborns.  Today, I looked at Nebraska's "report card" for premature birth, which you can find on the March of Dimes website.  We received a C.  11.5% of babies born in Nebraska are premature.  Many of those are due to unpreventable causes such as preterm labor or preeclampsia (a high blood pressure and vascular disease of pregnancy), but some can be prevented.  There is much research in this area, mostly funded through the March of Dimes, whose aim is for a prematurity rate of 9.6% or less by 2020.

So, what can be done?  Two major issues, especially in the state of Nebraska, which contribute to preterm birth, are lack of insurance coverage leading to inadequate prenatal care, and maternal smoking.  Another cause, which is improving, is elective preterm birth.  Even before 39 weeks of gestation, there are increased rates of prematurity-related health problems for newborns, including breathing problems, feeding problems, and difficulty maintaining body temperature.  The American College of Obstetricians and Gynecologists (ACOG) has set forth recommendations regarding when an elective induction or repeat cesarean delivery is considered safe.  Many hospitals have made these recommendations into hospital policy, and many physicians have adopted these policies even if the hospital does not have specific rules on elective delivery.

As a woman, what you can do is take care of yourself.  If you're a smoker, stop smoking.  Work on improving your diet and exercise habits.  Get prenatal care so that risk factors for preterm birth can be identified and managed for the best possible outcome.

I am so thankful that I did not have the personal experience of delivering a baby prematurely.  My hope is that fewer families will have to experience it.

www.marchofdimes.com