How Does A Baby Know When To Be Born?

Many parents-to-be wonder how does a baby know when to be born? It’s fascinating to ponder the mystery of it.

In the last few decades, researchers have been doing their best to answer questions about how and why babies are born.

Let’s find out how women’s and babies’ bodies work around the time of birth and what exactly triggers labor.

Does your body or your baby decide when labor starts?

We know the birth process is a team effort. Mother and baby are perfectly ‘in tune’, from the time conception occurs.

Research has beautifully explained how the placenta works.

It acts as the baby’s lungs, filling the blood cells with oxygen, and also works as the baby’s liver, filtering out and getting rid of any waste products. These are the best-known functions of fetal circulation.

The placenta, with the help of the attached umbilical cord, is also in charge of providing all the communication between a woman’s brain and her baby.

It’s a complex mechanism. Hormones, cell markers, enzymes, and DNA all travel through the blood system from one to the other.

The baby sends the mother the information about what is needed and the mother provides.

As one of nature’s best-connected teams, mother and baby work together, almost as one, to achieve the baby’s complete development and, when the time comes, a successful birth.

The due date

Your due date is mathematically calculated to mark the time when your pregnancy reaches 40 weeks. Basically, it involves adding 280 days to the first day of your last period.

If only it were that easy to know the exact date your baby was going to be born!

This method is not an individualized way of calculating each pregnancy. It’s a general one, based on average statistics. For example, it doesn’t take into account the different lengths of women’s menstrual cycles.

Human pregnancy is considered full-term between 37 and 42 weeks. This means babies are fully formed and ready to be born at any time during this five week period.

In fact, only 3-5% of babies are born on their given due date.

You can learn more about the due dates here.

You might also like to try BellyBelly’s Due Date Calculator.

What determines when a baby is ready to be born?

If a baby can be born at any time between 37 and 42 weeks, you might be wondering how the process starts up. How does a baby know when to be born?

What is it that sends labor signals to pregnant women, and tells the baby it’s time to be born and get ready to go through the birth canal?

Let’s look at the leading research in this area.

Research from the UT Southwestern Medical Center discovered certain cell markers that appear just before labor.

A cell marker is a molecule with a very specific role: to identify specific cells and bind with them so they can work together.

When these cell markers enter the amniotic fluid, the baby releases a combination of hormones that travel to the mother’s brain. This triggers a response in the mother’s uterus and cervix, basically saying, ‘Let’s take action. The changes we were waiting for are finally here’.

The researchers also found there was another very important internal factor that tells the baby it’s time to come out: the baby’s lungs.

Their study found two special proteins (SRC-1 and SRC-2) are released from the baby’s lungs into the amniotic fluid just before the beginning of labor. This causes an inflammatory response in the uterus that sends labor signals to the mother’s brain.

These two proteins also start the release of surfactants, which are substances that help baby’s lungs to work effectively after birth.

The baby must have surfactant in her lungs. It’s essential for breathing after a baby is born. Surfactant is so important that if there’s a high risk of preterm labor, doctors will give the mother steroid injections. This is to speed up the production and release of surfactant to help baby’s lungs develop faster.

In these cases, the obstetric team will try to stop labor from happening for at least 24 hours. That’s how long it takes for the injections to help with the production of surfactant in the baby’s lungs.

You might like to read What Causes Labor To Start for more information. 

How does your body know when to go into labor?

As we’ve just seen, Mother Nature always knows best.

Helped by the delivery of certain markers, enzymes, hormones, and surfactants, you and your baby work together. This team work starts up the body systems that will put an end to the pregnancy, and lead to the birth of your baby.

What are some signs that labor is near?

At the end of pregnancy, when the time to give birth is getting closer, the cervix starts to change. It becomes shorter and thinner (effaces) and opens up (dilates) in order to allow the baby’s body to pass through the vagina.

The release of the mucus plug often follows these changes, as the cervix is no longer tightly closed. You might notice some back ache that in hindsight pointed to the mild uterine contractions acting on the cervix.

When the first labor signals start, you might experience the feeling that your pelvis feels full or heavy. This is  your baby moving lower into the pelvis.

For more information be sure to read Signs Of Labor – 7 Signs You Might Be In Labor. 

How does a baby know when to turn head down?

This is a common question many parents ask after learning the theory behind the triggers for labor.

The baby has been growing in your uterus, guided by nature and with very little conscious brain input from you.

So how does a baby know how to get into the optimal head-down position for birth?

As you might have guessed, the answer might be less complicated than surfactant components, lung development, and complex hormonal activity.

The reason a baby turns into the head down or vertex position is simply a matter of space. As the baby gets bigger, there is less room in the womb, and the baby looks for the most comfortable position.

In most cases, this is the one where the head of the baby is close to your pelvis and the rest of the body is higher up.

Here is some useful information if your baby is in the breech position after 36 weeks.

Are babies awake during labor?

This is also a common question. Many parents want to know whether babies are asleep or awake during labor.

During pregnancy, a baby spends most of the time sleeping, particularly in the last trimester. This deep need for REM sleep is important for brain and nervous system development.

However, during labor, the baby spends more time awake.

Understandably, during labor the baby can feel that something quite different is happening. It’s important that the baby is awake, especially when birth is close.

The theory behind this is babies need to be alert when they are born so the correct bonding and attachment can happen.

Labor is a lengthy process and a baby who has spent most of her life sleeping requires a bit of rest every now and then.

During labor women rest between contractions; some might even nod off. But because the baby doesn’t feel the contractions the same way the mother does, she can sleep for much longer than the time between two contractions. It’s normal for a baby to sleep up to 30 minutes every couple of hours.

Birth From Your Baby’s Point Of View is a fascinating look at what babies sense and feel as they’re being born. 

Do babies feel pain during birth?

A woman can communicate with care providers and tell them how much pain she experiences during labor.

She can express not only its intensity but where she feels pain – in her body, vagina, back, or belly.

But do babies experience pain during labor?

There are no solid ways to measure the perception of pain in utero, but evidence suggests a baby can perceive pain. This is seen in changes to fetal heart rate during a medical procedure, or the mother’s perceptions of the baby’s reactions when a blood sample is taken during labor to check the baby’s pH.

Mighty hormones

Natural endorphins and oxytocin are released during labor and they cross the placental barrier so the baby also benefits from their effect.

We must bear in mind that when a woman is given synthetic oxytocin during labor, her own natural production stops. The placenta works so well to control what passes to the baby that it doesn’t allow artificial hormones to enter the baby’s circulation.

When the woman has an epidural, the production of endorphins stops as she is no longer in pain, and the baby has to navigate labor without these natural pain relief hormones.

It’s believed the main reason a newborn baby sleeps so much is to recover fully from birth.

Good attachment and lots of nurturing and love will get those healing hormones flowing in no time.