What *actually* starts labor?

Can We Predict the Start of Labor?

People (me included) say all the time, “Babies come on their own time.” And, this is true, they do. But, they don’t just randomly choose a day. It isn’t luck of the draw or even chance. So if there is something more to it, what *actually* starts labor? Let’s dive a bit deeper!

I know you’ve heard this before if you are not new around here, but your baby’s body and your body literally work together to start labor. They have been working together this whole time during pregnancy and will continue to work throughout birth and as long as you breastfeed. My mama would argue she can still feel when something is off from me (I live in Boston and she’s in Mississippi!) Your mama instinct is so strong. There are so many birthing people who say they feel like an induction isn’t the right choice for them and there’s research to show that you might be right! 

*You’re going to notice that some of these articles seem old. They are old because this isn’t new. This is something we are well aware of in the birth world. 

So, What Starts Labor?

Your baby’s lungs! That’s right, when your baby is ready to be born, their lungs will actually produce a hormone that mixes with your amniotic which triggers labor. “During the last part of your pregnancy, your baby's lungs mature and he or she puts on a protective layer of fat, taking on the characteristic chubbiness of a newborn. Researchers now believe that when a baby is ready for life outside his mother's uterus, his body releases a tiny amount of a substance that signals the mother's hormones to begin labor (Condon, Jeyasuria, Faust, & Mendelson, 2004). In most cases, your labor will begin only when both your body and your baby are ready.”

It’s also super important to remember that in late pregnancy your body is doing tons of work that is unseen. I’m not talking about dilation or effacement--things we can measure. I’m talking about things we can’t/don’t measure for like hormonal changes, the dropping of your baby, or the positioning of your baby’s head (more than facing forward or facing backward). There are so many things that your body does, like your hips and pelvis slowly opening up (an additional 30% in late pregnancy and throughout labor!) to make more space for baby and your breasts beginning to make and store colostrum! Your baby’s hormones will be speaking to your hormones and that will tell your body what to do. “The fetal hypothalamo-pituitary-adrenal axis plays a fundamental role in stimulating increased estrogen production in late gestation. Estrogen then activates maternal circadian rhythms that increase oxytocin secretion. As a result, uterine contraction patterns are switched from contractures to contractions.” (Nathanielsz, 1998) There’s plenty of research out there sharing the importance of your baby’s development in birth and some researchers suggest that answering critical questions about the hypothalamo-pituitary-adrenal axis can be key to reducing the number of preterm births and decrease the number of NICU stays (Wood and Wood, 2016). 

As your baby begins to produce these hormones, your body will begin to respond by prepping itself. This, for many pregnant people, looks like walking around a few centimeters dilated or effaced a bit! Your body is designed to be on the lookout for these signals from your baby! “Oxytocin receptors are probably crucial for the onset of human labor, and the stimulus for the increase in uterine prostaglandins may be oxytocin originating from the fetus.” (Fuchs, Fuchs, Husslein, Soloff, Fernstrom, 1982)

Remember, your baby is a separate being from you, but still dependent on you! They work together, but we shouldn’t force your body to try to control your baby.

So, What about Past Due Babies?

Don’t worry! Nature has that figured out too! We have to keep in mind that birth is a natural event--NOT a medical event. If you think about birth, humans are the only ones who trust other folks to birth their baby, birth in a medical environment, have tons of interventions and procedures “just in case”....If we step back and give nature the space to unfold as it’s intended to do, we can usually trust things to go right. 

So, if your baby isn’t here on your due date (uh hmmm, please remember that first time babies are usually born 40+5 to 41+2), there’s some research to take a look at before making your next move! “They found that changes in telomeres, part of our DNA that responds to aging, become present in the amniotic fluid as the placenta and other pregnancy tissues get older (source). These cells could be telling the baby that it's time to be born. "What made us suspect this signal is that we have always believed that labor can be triggered by the baby,"says lead author Ramkumar Menon, Ph.D., an assistant professor in the department of Obstetrics and Gynecology, and co-author George R. Saade, M.D., a professor and chief of Obstetrics and Maternal Fetal Medicine.”

So while babies will ‘come on their own time,’ they are actually still developing up until that point. We want to make sure we are balancing having a healthy respect for your baby’s growth and development when we talk about due dates and inductions! You can see more information on how your risk of c-section increases if your birth is augmented by way of induction here! 

The science is very clear what starts labor and that IS the baby’s body communicating to the gestational parent’s body via hormones and secretions that increase oxytocin and estrogen in the parent that then stimulates contractions. 

You can grab a free download to help master your mindset at the end of pregnancy! It can be so hard to patiently await your little one! I hear that 100%, but I also want to remind you to leave a healthy amount of space for your baby to work their magic as they are designed to do! If you want to learn more information to help you have an informed and confident birth, join our waitlist to be the first to know when The Birth Lounge opens again!

Ps. If you want a good birth story and one that empowers you to wait to trust in your baby, read this one!