What Triggers Labour to Start?

Pregnancy is a long process, but it all comes down to one important final event: labour. It’s something many women spend months, even years, wondering about, anticipating, and sometimes dreading. The experience is like no other, a mystery until you go through it for the first time. Even science cannot fully explain it. What triggers labour, what causes labour to start naturally, and why does it happen when it does?

As you reach late pregnancy, around 37 to 40 weeks, these questions often feel more urgent. Many start looking for signs of going into labour and thinking about how to start labour naturally. Recognising the signs of going into labor and understanding what your body is doing can help you feel more prepared.

In this article, we explain what happens before and during labour, including what triggers labour and the most common signs of going into labour, so you can feel ready for the final stage of pregnancy.

What Triggers Labour?

While you may be looking at your due date, 40 weeks after your date of conception, as something concrete, it really amounts to little more than an educated guess. In reality, term labour can happen anytime between 37 and 42 weeks. In fact, nearly a third of women don’t give birth within ten days of their expected due date, and only about five percent of babies are born on their actual due date.

So what exactly goes on in your body in those last few weeks that determines the onset of labor? What causes labor to start? The answer lies in a complex mix of hormonal changes, your baby’s readiness, and physical changes in your body. As your baby matures and signals that it’s ready for life outside the womb, your body begins to respond. Hormones like prostaglandins help soften and thin the cervix, while oxytocin triggers the contractions that eventually lead to labour.

Here are just a few signs your body is getting ready for labour.

Braxton Hicks Contractions Can Start Even Weeks Before Labour

Firstly, weeks or days before your delivery, you’ll probably start having something called Braxton Hicks contractions. These are not the real contractions that push the baby out during labour. Instead, they help your body prepare for the real thing. It’s essentially your uterus tightening and relaxing as it gets ready for birth. They are usually painless, though some women mistake them for true contractions, which is why they’re often called “false labour.” Unlike real contractions, they don’t lead to the onset of labor because they don’t cause the cervix to open.

Your Cervix Will Get Thinner and Softer

Speaking of your cervix, it also goes through important changes right before labour. As part of the hormonal process that causes labor to start, your cervix begins to soften, thin out, and prepare to open. This process, driven in part by prostaglandins, is essential for labour to progress.

You may also notice something called a show, which is the mucus plug being released. It often appears as a pinkish or blood-streaked discharge. While it’s not exactly pleasant, it’s a normal sign that your body is preparing for the onset of labor.

Signs of Going Into Labour 

In the days or hours before labour, your body may show early signs. Many parents wonder how do contractions start and notice them first as mild, irregular tightening of the uterus. You might also experience your water breaking, lower back pain, a bloody show, or cervical dilation as your body prepares for birth. Recognizing these signs of going into labor can help you know when it’s time to head to the hospital or birth center.

Other Signs of Your Body Getting Ready for Labour

• Cramping

• Loosening of joints

• Having diarrhoea, as your rectum is one of the pelvic muscles that loosens pre-labour

• Many women also report the phenomenon of nesting, or the desire to clean and organise in preparation for their baby’s arrival

• Lightening, which is when you suddenly have more room to breathe before labour. This happens because your baby engages or shifts further down your pelvis so that its head is facing toward your cervix in preparation to come out of the birth canal

Discover our toolkit for labour, where we discuss everything from creating a birth plan and packing your hospital bag to understanding the different types of births, pain relief options, and the role of partners.

How does labour start?

While all of the above early signs of labour can occur days and even weeks before you give birth, there are other symptoms that occur hours before labour that are even more useful as signs that labour has started. One of the best-known ones is when your “water breaks,” which usually happens no more than 24 hours before you go into labour.

Listen to conversations about birth experiences for more personal stories and insights on what it feels like to go into labour.

What Happens When Your Water Breaks?

Well, when your baby develops inside your womb, it lives in a bag of fluid, your amniotic sac. When your baby is ready to emerge, that sac will break, and all of the fluid will have no place to go other than to come out of your vagina. But it’s not always the dramatic event you see in movies. Sure, it may come out in a big rush, but it also may just trickle. And there’s a chance it won’t even happen at all and that your baby will be born still in the amniotic sac. That’s why you can’t rely on your water breaking as the only surefire sign that you’re going into labour.

You'll Know Labour Has Started When You Experience Regular Contractions

The only true symptoms of going into labour are the ones that are used to define the beginning of labour: having contractions. This is when your body works to open up your cervix so that your baby can come out. This happens when your uterus presses down on your baby, whose head then presses down on your cervix. This, and the release of the hormone oxytocin, will trigger contractions.

Contractions will probably feel like physical discomfort, dull aches, and pressure in your pelvis, back, and lower abdomen. A lot of women compare them to strong period cramps. Toward the beginning of labour, they’ll start out as weaker, shorter, and farther apart from one another. As you get closer to giving birth, they’ll become longer, stronger, and more frequent.

The Three Stages of Labour

Stage 1: Early Labour and Active Labour

Stage 1 consists of two steps: Early labour and active labour.

Early Labour Lasts from Hours to Even Days

The phase when your cervix dilates from zero to six centimetres is called early labour and it can last for quite a long time, as long as hours or even days. During early labour, your contractions will be mild and irregular at first and then progressively become more intense and frequent. Even though you may want to head to the hospital immediately, many doctors recommend staying at home during early labour, where you’ll be more comfortable and are less likely to need medical intervention.

During Active Labour, Contractions Feel More Intense

After your cervix expands to six centimetres, you’ll reach what is called active labour, when your cervix dilates from six to ten centimetres. During this stage, your contractions will come every three to four minutes, will last around 60 seconds each, and will feel much more intense and uncomfortable, to the point that it’ll be difficult not to focus on them. At this stage, you’ll want to head to your birthing place, whether that be the hospital or just a prepared birthing area in your home. Active labour will generally last between four to eight hours.

Stage 2: Pushing and Birth

Stage 2 of labour will be when you actually deliver your baby, which includes all of that pushing you hear so much about. This can take anywhere from a few minutes up to a few hours, though you can expect it to take longer if you’re giving birth for the first time.

Stage 3: Delivering the Placenta

Unfortunately, stages 1 and 2 are not the end of labour. In stage 3, you’ll deliver the placenta, which can take anywhere from five minutes to an hour. You’ll continue to have contractions and will need to push again in order to get the placenta out. After that, your uterus will immediately continue to contract in order to get back to its normal size. It’ll take up to six weeks for this process to be completely finished.

Learn more: Postpartum - A survival guide for the fourth semester.

Hormones Released During Labour

Just like with every part of pregnancy, there are a lot of hormones at play in the labour process.

• Oxytocin: It is often known as the cuddle hormone, as it is released when people snuggle up or bond. Oxytocin also plays a role in labour, as it can act as a contraction trigger (and also the letdown of your breast milk).

• Relaxin: This hormone is the reason for the loosening of your cervix, joints, and bowels, which comes along with labour.

• Prostaglandin: Helps open the cervix and allows the body to be more receptive to oxytocin.

• Beta-endorphins: A type of endorphin that not only helps with pain relief but also creates feelings of joy and euphoria. Beta-endorphins also slightly suppress your immune system so that it doesn’t overreact to the “foreign object” that is your baby.

• Epinephrine and norepinephrine: Also known as adrenaline and noradrenaline, which you might know as the fight-or-flight hormones. Typically associated with stress, a rise in epinephrine increases your levels of prostaglandin and cortisol, which stimulate contractions and help give you the energy to push during stage 2 of labour.

Learn more about pregnancy hormones; Why do they always seem to be all over the place?

What Triggers Labour?

All this useful information aside, you might still be wondering: does your body or the baby decide when labour starts? Or what hormone does the baby release to start labour? The truth is that the precise cause of labour remains one of the many medical mysteries that scientists continue to study. While we may not have all the answers, we have listed a few theories that provide some fascinating insights into the labor process and the onset of labor.

Hormonal Triggers

One of the key theories about what initiates labour revolves around hormonal changes. As the pregnancy progresses, the hormone progesterone helps maintain the uterine lining, preventing contractions. However, as the pregnancy nears full term, hormone levels drop, triggering a set of events which prepare the uterus for labour. This shift allows the uterus to contract and helps set the stage for delivery. Hormones released by the baby, such as cortisol, may also play a role in signalling the body to initiate labour.

Physical Factors

Physical developments within the baby’s body may also influence the start of labour. For instance, telomeres, which are a part of our DNA associated with aging, are present in higher quantities in the amniotic fluid as labour begins. Researchers believe this might signal to the baby that it’s time to be born. Similarly, the development of the baby’s lungs is critical. Around 32 weeks, the lungs produce surfactant protein (SP-A), which not only prepares the baby to breathe after birth but also activates immune cells in the uterus. These immune cells trigger an inflammatory response that could help initiate labour.

Emotional and Psychological Influences

While the physical and hormonal factors are significant, emotional and psychological aspects can’t be overlooked. Stress, relaxation, and the mother’s overall emotional state can impact hormone levels, such as oxytocin, which plays a crucial role in uterine contractions. A calm and supportive environment may aid the natural progression of labour, although it’s still largely influenced by the body’s internal processes.

Well, the potentially disappointing truth is that the precise cause of labour is one of the many medical mysteries that scientists still don’t have a real answer to. The best we can do is share a few theories that scientists are considering for possible causes of labour.

Inducing Labour at the Hospital

Now, all of this science-y talk is all well and good, but you can’t exactly inject yourself with surfactant proteins if you want to induce labour. So, what can you do?

Interestingly, about 25% of all labourers in the United Kingdom are induced, most often because the mothers are considered overdue to give birth, usually at around 42 weeks. Doctors will choose to induce labour in order to reduce risk to both mother and baby, as there is a higher chance of stillbirth and other complications if you go over 42 weeks pregnant.

• In the hospital, inducing labour is done by applying a topical form of the hormone prostaglandin to the cervix.

• If this isn’t an option because of reasons such as the mother having had prior uterine surgery, a doctor may choose to open the cervix mechanically with a catheter or graduated dilators instead.

• To encourage a woman’s water to break, a practitioner might swipe their finger along the membranes that connect the amniotic sac, which triggers the uterus to release prostaglandin, softening the cervix and causing contractions.

• If this doesn’t work, the doctor may even manually rupture the amniotic sac.

• If, after a few hours, none of these steps brings on regular contractions, doctors will typically administer Pitocin, a synthetic form of the hormone oxytocin, intravenously. This is usually successful at triggering contractions within half an hour, and these contractions are stronger, more regular, and more frequent than those that occur with natural labour.

Natural Ways to Encourage Labour 

In some situations, women may feel the urge to help things along and induce labour at home before medical induction is considered. While there are various methods people commonly turn to, it’s important to understand that most lack scientific backing and are often based on anecdotal evidence. While some women swear by these methods, there is no definitive proof that they actually work. So, if you're wondering how to bring on labour, how to start labour, or how to start contractions after water breaks, here are a few methods commonly tried:

• Moving around:  Light activities like walking or climbing stairs are thought to help your baby drop further into your pelvis, potentially encouraging the start of labour and helping to start contractions.

• Having sex: Sex can stimulate the uterus and trigger the release of oxytocin, both of which are thought to help induce labour and bring on contractions. Semen also contains prostaglandins, which might affect the cervix.

• Membrane sweep: A healthcare provider can gently separate the membranes from the cervix, which may release prostaglandins and help bring on labour.

• Relaxation: Techniques like deep breathing, prenatal yoga, or meditation can reduce stress and support your body’s natural readiness for labour.

• Acupuncture: When performed by a trained professional, acupuncture may stimulate uterine activity and help encourage contractions.

Ultimately, whether you choose to try to induce labour at home, use these ways to start labour, or wait for it to happen naturally, it’s important to carefully consider your individual situation and consult with your healthcare provider.

Can You Induce Labour at 37–39 Weeks?

37 Weeks
At 37 weeks, babies are early term, so doctors usually recommend waiting for natural labour. Many wonder how to induce labor at 37 weeks, but any attempts should be discussed with your healthcare provider.

38 Weeks
By 38 weeks, babies are fully developed, though most doctors still prefer natural onset. Parents often search for 38 weeks pregnant how to bring on labour, and some natural methods may be considered safely.

39 Weeks
At 39 weeks, labour is full term and medical induction may be offered. Searches include how to speed up labor at 39 weeks and 39 weeks pregnant induce labor. Always consult your doctor before trying to bring on labour.

Common Myths About Labour Triggers

When it comes to labour, there are many myths floating around. From spicy foods to bizarre old wives’ tales, it can be hard to know what to believe. Let’s clear up some of the most common misconceptions with the facts:

Myth: Eating spicy foods induces labour
Reality: There’s no evidence to support this! While spicy foods might cause indigestion, they won’t kick-start contractions.

Myth: Walking a lot speeds up labour
Reality: Staying active is great for overall health, but there’s no proof that walking can trigger labour to start.

Myth: Castor oil induces labour
Reality: Castor oil may upset your stomach and cause diarrhea, but its effects on inducing labour are uncertain.

Myth: A full moon causes more births
Reality: It’s a fun idea, but studies show no link between moon phases and childbirth rates.

Myth: Pineapple softens the cervix
Reality: Pineapple contains bromelain, but not in large enough amounts to make an impact on labour.

Labour begins when your body and baby are ready—no shortcuts or old wives’ tales can change that. Keep calm, and trust the process!

When to Contact Your Doctor

Contact your doctor if you notice reduced baby movement, your water breaks without contractions, or you have vaginal bleeding. These can signal complications and need medical evaluation.

Recover Better After Childbirth

No matter how you gave birth, the first six weeks postpartum are considered a recovery period. Your body has been stretched and stressed to the max and needs a chance to regroup. Keep in mind that every new mum is different, so every woman will recover at a different rate with different postpartum symptoms.

After birth, your stomach muscles are separated and much weaker. The gentle compression of a postpartum belly wrap encourages your muscles to push together, activating your deep core muscles, healing your tummy pouch, and avoiding long-term complications. Learn more about the Lola&Lykke Postpartum Support Band for better recovery.

If you have more questions about childbirth, pregnancy, or postpartum care, visit our free consultancy service - Ask Lola&Lykke Experts. Your safe and non-judgemental support platform.

FAQ

How can I bring on labour fast?

Some natural methods may help jumpstart labor, such as gentle walking, nipple stimulation, or sexual activity. Always consult your doctor before trying anything.

Can orgasm bring on labour?

Yes, orgasm can release oxytocin, which may help kickstart labour, but results vary.

What helps you go into labour tonight?

There are no guarantees, but ways to go into labor now can include movement, relaxation techniques, or professional methods like a membrane sweep.

How do contractions start?

Contractions begin as your uterus responds to hormonal signals, gradually increasing in intensity and frequency.

Can walking start labour?

Walking and gentle movement can encourage the baby to move into position and sometimes help bring on labour.