The Role of Prostaglandins in Labor

Prostaglandins are tiny chemicals in our bodies that help regulate different biological processes. You can think of them as little helpers that play a big role in things like reproduction, including pregnancy and childbirth. They help soften the cervix (that’s the part of the uterus that opens during labor), make the uterus contract, and even help break the water bag when the baby is ready to come out.

The most famous prostaglandins involved in labor are PGE2 and PGF2α. Doctors have been using these prostaglandins and their synthetic versions since the 1960s to induce labor or make it stronger. It’s like giving nature a little nudge when it’s not quite ready to start the show.

Other prostaglandins, like PGI2 and PGD2, have different roles. Although they’re not used in the same way during labor, they are still players in the complex game of pregnancy. All these prostaglandins belong to a larger family of similar substances called eicosanoids. Think of eicosanoids as the extended family of prostaglandins.

#Why Do We Care About Prostaglandins?

Understanding how these chemicals work can help doctors manage labor better. This is especially important when it comes to preterm labor, which can be a serious issue for many babies and their parents. Preterm labor is when a baby is born before 37 weeks of pregnancy. It’s one of the biggest reasons for health problems in newborns.

Many scientists have suggested various indicators or “Biomarkers” that might help predict when someone will go into labor early, but so far, nothing has been reliable enough to use in a hospital. In fact, around half of the individuals showing signs of preterm labor will actually go on to deliver at full term. This makes it tricky for doctors to know who really needs extra care.

If we can accurately measure certain biomarkers, especially in urine, we might be able to give targeted help to those who really need it. This is where our hero, prostaglandins, comes back into play. There’s some evidence that levels of prostaglandins in a woman’s urine go up when labor starts. Since urine is easy to collect, it could be a good option for doctors looking to identify women who might go into early labor.

#The Mystery of Labor Onset

Despite the importance of prostaglandins, we still don’t fully understand how they kick off labor. If we did, it would make things much simpler for everyone involved. There’s a lot of speculation about what triggers preterm labor, and many suggestions have been made, but no clear answers yet.

Some studies have shown that when women are close to labor, certain prostaglandin levels rise, but there’s no guarantee that this happens for everyone. This is important because having a reliable indicator for labor could mean the difference between a healthy delivery and preterm birth.

#What Researchers Set Out to Do

Researchers wanted to find out if measuring specific prostaglandins in urine could help understand when labor is about to start, particularly for women experiencing threatened preterm labor. They also wanted to see if there are any other eicosanoids involved during labor that could potentially be useful.

Their plan was pretty straightforward. They would look at the urine of pregnant women at different points—both those in labor and those who weren’t—especially focusing on those at risk for preterm labor. This included women who showed signs of labor but hadn’t actually delivered yet.

#Finding Participants

The researchers got approval from a local ethics board and made sure everyone involved knew what they were getting into. Women from a Calgary hospital were recruited from May 2018 to July 2020. The participants were divided into groups based on whether they were at term (37 weeks or more) or preterm (less than 37 weeks), and whether they were in labor or not.

The groups looked like this:

1. Term Non-Labor (TNL) - 32 participants
2. Term Labor (TL) - 49 participants
3. Preterm Non-Labor (PTNL) - 15 participants
4. Threatened Preterm Labor with Preterm Delivery (TPTL-PTD) - 43 participants
5. Threatened Preterm Labor with Term Delivery (TPTL-TD) - 44 participants

The term non-labor group included women ready for induction or a C-section. The term labor group consisted of women whose labor started on its own and who delivered between 37 and 42 weeks.

#Collecting Samples

Once the women were recruited, they provided urine samples in sterile containers, which were then frozen for later analysis. The researchers also collected clinical information, like how dilated the cervix was, and how long the membranes had been ruptured. This additional data helped provide a fuller picture of what was happening with each participant.

#Analyzing Prostaglandin Levels

To measure the levels of specific prostaglandins in the urine samples, researchers used a technique called enzyme-linked immunosorbent assay (ELISA). They had several kits that allowed them to measure various prostaglandin metabolites, including PGFM and PGEM, among others.

When the results came in, they were able to compare levels of these substances between different groups of women. Overall, women in labor showed higher levels of certain prostaglandins compared to those who were not in labor. This was expected and supported the idea that prostaglandins play a role in the labor process.

#What the Results Show

The research found that certain prostaglandin levels were higher in women who were actually in labor compared to those who weren’t. For example, the levels of PGFM, PGEM, and PGF2α were notably elevated in the term labor group, while the preterm labor group didn’t show significant differences based on delivery timing.

However, the researchers didn’t find strong evidence that urinary levels of prostaglandins could reliably predict labor. While the levels went up during labor, they didn’t appear to change significantly beforehand, at least not consistently.

It seems that just because a woman might have some signs of early labor, there’s no guarantee that it’ll lead to preterm delivery. This is a bit of a letdown for anyone hoping for a surefire way to predict labor.

#Cervical Ripening and Prostaglandins

Cervical ripening is a key part of the labor process. This is when the cervix softens and prepares for the baby to be delivered. The researchers found that one type of prostaglandin, PGEM, was positively linked to cervical ripening, but only when women were at term. In preterm situations, other substances showed a negative association, which was a bit puzzling.

Despite extensive research showing that prostaglandins can help with cervical ripening, it’s still unclear whether the rise in these chemicals is what causes cervical ripening or simply a result of it. So, it’s a classic chicken-or-egg dilemma in the world of biochemistry.

#What About Preterm Labor?

The study also wanted to see if prostaglandins could help distinguish between preterm labor cases that resolved and those that didn’t. Some previous studies suggested that certain prostaglandin levels might be higher in women who end up giving birth prematurely. But this study didn’t find strong evidence to support that idea.

Interestingly, the researchers did find that PGIM levels were higher in women who eventually delivered at term compared to those who delivered preterm. This suggests that while prostaglandins are important, they might not be the hero we’re looking for when it comes to predicting preterm labor.

#The Bigger Picture: Other Eicosanoids

The study didn’t just stop with prostaglandins. Researchers also wanted to look at other types of eicosanoids in urine that could potentially be useful as indicators for labor. They discovered several new eicosanoids that could also be involved. Some of these were detected in at least half of the samples tested.

Interestingly, some earlier studies indicated that specific eicosanoids might be more effective in predicting preterm birth than the traditional prostaglandins. This opens up new avenues for research and could lead to a better understanding of what’s happening during labor and delivery.

#Wrapping It Up

While prostaglandins play an important role in labor and delivery, this research indicates they aren’t the magic solution for predicting when labor will begin. There’s still a lot to learn about how these substances work, especially in the context of preterm births.

Scientists are hopeful that further exploration into these and other eicosanoids could lead to the discovery of more reliable biomarkers for labor. With some luck and continued research, we could soon have a clearer picture of labor—helping doctors and parents alike prepare for the big day.

So, the next time you hear about prostaglandins, remember that these little chemicals are working hard behind the scenes, even if they haven’t quite figured out the timing of the curtain call.