Things That Probably Won’t Happen

Should older moms-to-be worry about having a baby with Down Syndrome?

Posted Apr 10, 2014

Probably no one would argue that worrying is a good idea, especially here on the Pyschology Today website, right? Perhaps you have seen a cross-stitched sampler that reads, “Worry is like a rocking chair: it keeps you busy and gets you nowhere.” Or something like that.

Yet in pregnancy we seem to forget this, especially if the mother is a bit older. Just last week a colleague who is cautious but probably would not qualify as an official worrywart was describing his 42-year-old daughter’s pregnancy. He said that they worried because of her age but that she got lots of screening tests and everything was fine.

In fact, things were most likely going to be fine.

Sometimes people act like worrying is a sign of being conscientious and that screening tests are actually a form of prevention instead of diagnosis. One of the reasons women have been told to panic about having children later in life is that it may taken longer than expected. We have discussed these expectations in previous posts here and here.

Older womenespecially those over 40are often encouraged to think that their age may be bad for the baby. This is a huge subject, because the potential adverse outcomes are manypreterm birth, low birth weight, Down Syndrome, physical birth defects like cleft palate, and autism. They have different roots causes. Here we will take Down Syndrome as an example, because it is strongly correlated with maternal age, and it is most common genetic disorder and form of intellectual disability.

One caveat: studying birth defects is difficult because these fetuses are more likely to be lost to abortion, miscarriage, or stillbirth. Slightly different numbers are presented from different sources.  One analysis based on a very complete data source from England and Wales calculate the odds of having a baby with Down Syndrome by maternal age roughly as follows:

Age 30 – 1 in 937

Age 35 – 1 in 352

Age 37 – 1 in 199

Age 39 – 1 in 111

Age 40 – 1 in 85

Age 42 - 1 in 54

Expressed as a rate, among women aged 35, there are about four Down Syndrome babies per 1,000 live births. Among women aged 40-45, there are about 20 per 1,000.

What is your reaction to those numbers? Mine is that having a baby with Down Syndrome is unlikely at any age. Among mothers age 40, they have a 98 percent chance of not having a baby with Down Syndrome. It is not as unlikely as winning the lottery, but it is not something I would plan on. I would even argue that we should not change our life plans dramatically based on that level of risk. (I know others will disagree. They always do.)

Also, saying that there’s a strong association between an outcome and maternal age is not the same as saying that age caused the birth defect. Putting aside rates and odds (with a sigh of relief for those who disliked math class), most babies with Down Syndrome are born to mothers who are less than age 35.  

Here’s a remarkable fact from Wilcox’s review of the research: only 60 percent of identical twins have the same birth defect.

Same genes + same environment = different babies. 

 (This is really where religion starts to fill in science’s gaps, doesn’t it?)

Does that mean you shouldn’t get screened for genetic disorders during pregnancy, because it will just cause needless stress? Not necessarily.  Some women avoid getting screened if they feel certain that they would never abort a fetus with a birth defect. That’s fine, but you should know that the screening, which includes a blood test and an ultrasound, may be reassuring. If you are over 35, your risk projection will be elevated based on age alone, and the findings of the screening may make the risk less likely. 

In other words, the screening could very well make you worry less, although you should follow our advice and minimize the worrying anyway.

Another thing to note: some research suggests that when people think about Down Syndrome, their have concerns that are actually worse than the reality. (That’s true of most worry, isn’t it? It’s easy to catastrophize.) Although Down Syndrome is not curable, most people with Down Syndrome live long and productive lives, contrary to popular misconception. Also, according to one study, when asked to imagine having a child with Down Syndrome, women expressed concerns that were not supported by the available research, such as that it would be hard on their marriage or that it would lead to sibling resentment.

We won’t give you a bright smile and say, “Don’t worry.” That does nothing to help a person stop worrying. If you want to tame your raging thoughts, then you certainly have come to the right website.  Just remember, as mothers, the surest way we can make ourselves miserable is to overestimate the influence we have on our children. We need to struggle against this tendency right from the time of conception.

 If you want to find out about new posts, follow us on twitter: @beyondeggtimer 

About the Author

Sharon I. Praissman is an adult (medical) and psychiatric mental health nurse practitioner.

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