Past Your Due Date? What It Really Means for You and Your Baby

Are you past your due date and feeling the pressure? Many women hear that their baby is “overdue” and feel rushed to induce labor. But what’s the real risk of waiting a little longer? In this post, we’ll dive into the truth behind due dates, the risks of going beyond 42 weeks, and how you can make an informed choice for you and your baby.

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Can your baby be “overdue”? Can your placenta get too old to work properly? Does a too-big baby lead to problems during labor?

Those and more are the questions women need answered when they approach their due date with no signs of labor.

Though due dates are often inaccurate, they are important to women and they can be important for the health of moms and babies. And while many care providers start to worry as soon as you’ve past 40 weeks, the concern is heightened if you get to 42 weeks pregnant.

But why?

Is it really dangerous to wait to go into labor naturally, even if it takes a little longer than expected?

That’s exactly what I’m going to go over in this blog post.

The Deal With Due Dates

The first thing that we need to discuss is due dates. You can’t be “42 weeks pregnant” unless you knew a due date (when you were going to be 40 weeks) in the first place. And that’s one reason this whole “post term pregnancy” thing is tricky.

(“Post term” is what you are labeled once you hit 42 weeks.)

A woman’s due date is typically 40 weeks (or 280 days) from the first day of her last menstrual period. But a lot of factors can affect how accurate that 40-week estimate is.

First, who said women were supposed to have their babies exactly 280 days after their last period started? In truth, it’s just a rough estimate…one now based on cultural norm rather than research.

Second, that 40-week estimate is based on a 28-day menstrual cycle. But not all women have a 28-day cycle.

Third, every woman has a unique physical makeup. Her medical history, genetics, health habits, and more can affect how likely she is to give birth at that 40-week mark.

For those reasons and more, putting too much stock in one day as the expected day of birth really does more harm than good.

Being “Early” or “Late”

While I’m not a fan of the concept of due dates (I like “due window” better), the medical management of pregnancy revolves around due dates, so I’ll quickly explain how you’ll hear the timing of birth talked about.

According to current definition, this is how things are broken down:

A baby born before 37 weeks is considered “preterm” or “premature”
A baby born between 37 weeks 0 days and 38 weeks 6 days is considered “early term”
A baby born between 39 weeks 0 days and 40 weeks 6 days is considered “full term”
A baby born between 41 weeks 0 days and 41 weeks 6 days is considered “late term”
A baby born at 42 weeks and 0 days or later is considered “post term”

“Late term” and, especially, “post term” are what we’re focusing on today.

It’s worth pointing out that “true” post term babies are rare.

As is summarized in this professional article, “The reported frequency of post term pregnancy is approximately 3–12%. However, the actual biologic variation is likely less, because the most frequent cause of a post term pregnancy diagnosis is inaccurate dating.”

In simpler terms, most of the time a “post term pregnancy” isn’t actually post term; the due date was just too early.

Why the Worry About Being “Overdue”?

So why do doctors worry so much when women go past their due date? To some degree, it’s not all on them. Hospitals and medical organizations take a long time to apply good practices even after there’s ample evidence backing those practices up.

Plus, new doctors learn from older doctors. And if the older doctors induced women once they were past their due date, the new doctors are probably going to do the same thing.

In addition to that, there’s just a lot of fear.

Doctors have been trained to see pregnancy as a high-risk condition, especially when it goes longer than they expect. And when a doctor fears something, he is going to pass that fear onto his clients, intentionally or not.

Whether because of financial or scheduling reasons or simply because they are unaware of the realities of longer pregnancies, doctors often provide biased or incomplete information to pregnant women.

Because of that, it’s easy for a woman to accept an induction (or other medical intervention) without knowing the full risks and benefits of all her options.

All that said, if a woman’s due date is accurate and she gets to 42 weeks, her risk of a few things does increase…slightly. But it’s more complicated than a simple widely-given recommendation.

When Induction is Likely Unnecessary

Before we get to the risks of true post term pregnancy, I want to share a few things with you that can help you know things are still good with your pregnancy and your baby after that 40-week mark.

When You’ve Had a Healthy Pregnancy

First, if you’ve had a healthy pregnancy, it’s unlikely that your baby’s health will suddenly change after the due date, which, like we talked about, is more accurately a general window of time than a strict deadline.

If you have been eating well, staying as active as you can, and being mindful of your mental and emotional health, you have every reason to believe that things are going to be just fine, even if you reach (or go past!) 42 weeks of pregnancy.

Of course, as always, be in tune with your body and your baby. If anything is wrong, you will likely know it intuitively before a doctor detects it.

When Your Baby Is Still Active in the Womb

This is where “kick counting” comes in. I actually didn’t hear about kick counting until after I’d had my first baby. I didn’t know it was something women did.

The idea behind kick counting is that if you’ve been paying attention to how often your baby moves, it will be obvious to you if the frequency of that movement decreases. Decreased movement can be an early indicator of distress (for example, in the case of restricted blood flow through the placenta).

Some care providers and women believe that a mother’s perception of her baby’s kicks and movement is the best indicator of her baby’s well-being. I can get behind that.

So if you still notice your baby moving and rolling around in your belly as much as they always have, you can probably assume all is well.

When the Tests Look Good

This one is tricky, and we’ll get into that. But if amniotic fluid levels are normal, your baby has a normal heart rate, and they have been growing consistently, simply going past your due date should not be a problem.

Risks of Going Past 42 Weeks

Overall, there are 6 main risks of going past your due date that you’ll hear doctors and others talk about. They generally become more of a risk the closer you get to 42 weeks. (We’ll talk about the legitimacy of each of the risks in a moment.)

These 6 post term pregnancy risks are…

Stillbirth
Postmaturity syndrome
Macrosomia (a big baby) and related injury
Meconium aspiration
Decreased fluid levels
Placental “aging”

While other things could be added to the list, these 6 are the most cited and could be considered the root cause of other risks that may arise.

How Risky Are These Risks?

While the 6 risks I listed above are legitimate concerns, they are often both overstated and under-explained.

So allow me to simply state and thoroughly explain each.

We’ll start with stillbirth.

Stillbirth

Stillbirth is when a baby dies in their mother’s womb after 28 weeks of pregnancy (in the third trimester).

Of course, both parents and doctors want to do all they can to avoid a stillbirth.

When it comes to going “overdue” in your pregnancy, doctors will often tell women that they need to induce labor to avoid the increased chance of stillbirth.

They’re right about one thing: the risk of stillbirth does gradually increase as pregnancy continues beyond 40 weeks. Let’s look at the numbers.

At 37 weeks, the risk of stillbirth is 2.1 per 10,000 pregnancies.
At 40 weeks, the risk is 4.2 per 10,000.
At 42 weeks, the risk of stillbirth is 10.8 per 10,000.

So, put one way, the risk of stillbirth doubles from 37 weeks to 40 weeks and then increases by another 2.5 times from 40 weeks to 42 weeks.

But put another way, your chance of stillbirth at 37 weeks is 0.021%, at 40 weeks it’s 0.042%, and at 42 weeks it’s 0.11%. Yes, it increases, but it is still a tiny number!

Here’s my point:

The crux of the issue isn’t the risk of stillbirth. It’s each woman’s perception of that risk.

The increased risk of stillbirth has to be weighed against the risks of baby being born early (induction). BOTH have risks.

For some women, the small chance of stillbirth (that 0.11%) is enough for them to choose to take on the risks of their baby being born a little early. This may be the case for someone who has experienced pregnancy loss before.

For other women, the combined risks of induction and prematurity outweigh the small increase in the risk of stillbirth.

There isn’t a right answer here.

But it’s not the doctor’s place to decide.

Postmaturity Syndrome

Postmaturity syndrome is diagnosed based on how a newborn baby looks. The appearance of this syndrome may include…

Dry, loose, peeling skin
Overgrown nails
Longer, thicker hair on the head
Visible creases on palms and soles of feet
Small amount of fat on the body
A “wide-eyed” look
No vernix on skin (the white creamy substance normally present at birth)

People say that 20% of babies who are born post term will have postmaturity syndrome. That works out to be roughly 2% of babies (likely less) that will be born with this unique appearance.

Beyond the agreed-upon physical appearance, the idea of postmaturity syndrome is confusing if you really try to break it down.

Here’s what I found in all my digging.

A Form of Fetal Growth Restriction?

Some people say postmaturity syndrome is different from fetal growth restriction (FGR). Others say it is a form of FGR. With what I’ve learned, the latter makes the most sense. The claim that a healthy baby’s growth might stop as soon as they reach their “due date” (remember, that’s a cultural norm, not physiology) just doesn’t make sense.

It makes far more sense to me that a baby who appears the way described above would have been struggling for much more than the last 2 weeks or so of pregnancy.

Caused by the Length of Pregnancy?

It’s also common to hear that postmaturity syndrome is simply caused by a long pregnancy. I frankly don’t think that has any legs to stand on, either.

Every person is different—mother, father, and child. So assuming every baby will follow the exact same time line of development and birth is illogical. (Just think about how different menstrual cycle lengths can be from woman to woman!)

Ask pretty much any home birth midwife and she’ll tell you that she’s seen plenty of women that have had long pregnancies (even 42 weeks and beyond) with no complications.

Symptom of Other Complications?

The last thing to know about postmaturity syndrome is that it is almost always listed with other complications of post term pregnancies: low amniotic fluid, placental problems, and meconium aspiration (each of which we’ll cover in a moment).

But no one seems to clearly distinguish between these risks and postmaturity syndrome.

What I’m saying is what if postmaturity syndrome—meaning the way these babies look—is a symptom of other complications and not a risk in and of itself?

Whatever the case (it seems we’ll have to go on gut instinct for now), one study did show that infants born with this “postmaturity syndrome” did just as well at 1–2 years old in terms of IQ, physical milestones, and avoiding illness.

Macrosomia

Another concern doctors have when women go past their due date is macrosomia, or a big baby. Babies can get abnormally big (bigger than they “should” genetically) but it’s rare. And it’s most common for women with diabetes.

But macrosomia is defined as a baby bigger than 8 pounds, 13 ounces. That’s it. It’s just one static threshold based on weight.

The main reason big babies cause worry is because of the possibility of shoulder dystocia.

True shoulder dystocia is a medical emergency. But it’s uncommon. And if handled well, it is usually resolved within a few minutes without any injury to baby or mom.

Plus, shoulder dystocia can happen even when a baby is average-size or small!

Most of all, what’s important to know about macrosomia is that a doctor’s assumption that a baby is big (correct or not) is actually more dangerous to a woman and her baby, in terms of outcomes, than an actual big baby.

Meconium Aspiration

The next concern people have when a baby goes past their due date is meconium aspiration. Meconium aspiration is when a baby poops while still in the womb (the poop is called meconium) and that baby breathes the meconium into their lungs.

Meconium staining—when babies poop into the amniotic fluid before birth—is fairly common. It can be a normal sign of a baby’s development. Meconium staining alone is NOT an emergency.

Meconium in the fluid becomes an emergency when it is inhaled. That happens about 5% of the time when there is meconium staining. But of those who really struggle to breathe after birth because of meconium aspiration, about 97% of them will recover, most of them quickly!

So is meconium aspiration a risk?

Yes. But a very small one.

And get this: meconium aspiration is linked to fetal distress. If a baby isn’t receiving enough oxygen, they will often take gasping “breaths” of amniotic fluid. If there is meconium in their fluid, this gasping will likely lead to inhalation.

And do you know what one of the main causes of fetal distress is during labor? Induction.

So if you want to avoid meconium aspiration, worry less about going past your due date and more about your baby’s experience of late pregnancy and birth.

Decreased Fluid Levels (Oligohydramnios)

Amniotic fluid is an essential part of pregnancy. But the fluid level naturally changes throughout pregnancy.

The amount of amniotic fluid increases until 34–36 weeks of pregnancy and then starts to decrease after that, for as long as the pregnancy continues.

So. Is decreased fluid levels a problem or the physiological norm?

Well, both.

For most women, a slight decrease in amniotic fluid levels after 40 weeks likely isn’t going to indicate a problem. It’s just what is bound to happen and baby will usually be just fine.

Occasionally, amniotic fluid levels will decrease too much or will be accompanied by other signs of fetal distress and therefore are a “problem.”

(I will point out, though, that the cut off “low” amniotic fluid levels was chosen arbitrarily.)

If amniotic fluid levels truly are lower than would be ideal, possible complications include…

Umbilical cord prolapse and compression (which may require birth by c-section)
Meconium aspiration
Low heart rate
Premature birth (before 37 weeks)
Stillbirth

Rarely, having too little amniotic fluid for too long can cause your baby’s muscles to lose their function and cause lasting disability.

These complications are the same whether oligohydramnios (the fancy term for low amniotic fluid levels) happens before or after 40 weeks. It just depends on how much fluid there is.

Placental “Aging”

Finally, we need to talk about the idea that a placenta ages and gets too old to function properly if pregnancy lasts longer than 40 weeks.

While studies have found evidence that placentas do show signs of maturing and changing over time, there is no reason to suspect that they lose their ability to function well. In fact, placentas are usually quite good at adapting to circumstances and doing what is needed to continue to provide the baby with what he or she needs.

In cases where the placenta really isn’t providing enough nutrients and oxygen to the baby, that risk will usually be obvious long before 40 weeks.

To dig more into the issue of “placental insufficiency” and the “myth of the aging placenta,” go to Is the “Aging” of the Placenta a Problem?.

Induction or Going “Overdue”?

Now you know the 6 main risks of going past your due date. You have a better understanding of the real likelihood of each risk and what it might mean for you.

And that means that you can now make a truly informed choice about getting an induction around your due date or letting your baby go “overdue.” That is something every woman deserves.

Until next time,

Allison

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Past Your Due Date? What It Really Means for You and Your Baby