Predicting when your baby will be born and whether she’ll arrive early, on time or late has been a mystery since the time of Hippocrates, the ancient Greek physician known as the father of medicine, who developed the Hippocratic Oath, still accepted by physicians today. Medical experts in 2020 are still trying to solve the mystery to predict whether the timing of your baby’s delivery will be preterm, at term or post-term.
Jade Elliott spoke with Dr. Helen Feltovich, a maternal fetal medicine OB/Gyn and associate professor at Intermountain Healthcare who manages high-risk pregnancies to shed some light on the mystery of the possible causes of preterm birth.
What is the definition of preterm birth?
Babies born at 37 weeks or later are considered at term. For babies born before 37 weeks, the earlier they are born, the more likely they are to have health issues. So, we categorize preemies into these general categories.
Babies born between:
34-37 weeks are considered late preterm
34 or 32 weeks are considered early preterm
26-28 weeks are considered very early preterm
Does preterm birth just happen on its own or are there reasons why it would be recommended for a mom to give birth before 37 weeks?
Preterm birth can be either medically-indicated (because continuing pregnancy is not safe for the mother, baby or both) or spontaneous (labor happens on its own). Currently, at least 2/3 of preterm births are spontaneous, and, while we do know some factors increase the risk of preterm birth, most preterm births actually have no biological explanation. Unfortunately, by the time labor is happening, we have no therapies at all that can stop it.
Why is it so difficult for physicians to predict preterm birth?
While physicians have various ways to try to guess at when a baby will deliver, like how long or dilated the cervix is, none of these work well, even during labor itself, to predict when a baby will be born. Preterm birth is particularly vexing to OB/Gyn caregivers because of its potentially serious health consequences to the newborn.
What are some of the challenges in preventing preterm birth?
Preventing preterm birth is even more challenging because we have only two basic approaches, that have been around since about the 1950-1960s and they both have limits in their effectiveness. One of these approaches is progesterone (hormone) supplementation, which although it’s been tried in various formulations and doses, prevents preterm delivery less than half of the time.
The other approach is mechanical support of the cervix by cerclage (basically stitching a purse-string around the cervix), which prevents preterm birth less than half of the time.
Although these therapies don’t work all the time, they certainly work some of the time in the right patients. So, it’s very important to see a high-risk pregnancy specialist, ideally before pregnancy, to discuss which approaches might be appropriate for the next pregnancy.
This lack of overall progress seems astonishing, but it’s because preterm birth is so complex, and there are so many factors that come into play, and so many different pathways.
What are some of the possible risk factors that may lead to preterm birth?
Studies show the two strongest risk factors for preterm birth are:
- History of PTB, and
- Short cervix during your current pregnancy
Other risk factors include:
- Infection or inflammation
(There are many different types of infections or causes of “sterile” or non-infectious inflammation. Some studies have shown that COVID-19 increases the risk of preterm birth).
- Smoking or substance abuse during pregnancy
- Short time between pregnancies (less than 18 months)
- Expecting multiples, twins, triplets, etc. 50 percent of twins come early.
- Vaginal bleeding
- Abnormal shape of the uterus
- Maternal and fetal stress (probable, difficult to measure/prove)
What about stress – how does that have an impact?
Stress is a very difficult thing to measure, because there is physiological stress, psychological stress, and a combination of the two and they do all kinds of things in a person’s body. That said, it is becoming increasingly clear that social determinants of health that are associated with both physiological and psychological stressors (like education, income level, ancestry, race or ethnicity, access to healthcare, social support, etc. can change preterm birth risk.
The COVID-19 pandemic is highlighting this, because in some countries (like the Netherlands), the rate of preterm birth has decreased among higher income women, thought perhaps due to less stress because of working from home, etc, while in the U.S. (where we do not have widespread governmental support for income maintenance, or universal healthcare), the CDC data suggests an increased risk of preterm birth. This is an extremely complex issue, which affects an extremely complex and multifactorial outcome (preterm birth), but this pandemic is showing us new ways to look at potential contributors to and solutions for preterm birth.
What kinds of symptoms of preterm labor should a woman call her doctor about?
- Call your obstetric provider right away if you notice any of these signs or symptoms:
- Change in type of vaginal discharge (watery, mucus, or bloody)
- Increase in amount of discharge
- Pelvic or lower abdominal pressure
- Constant low, dull backache
- Mild abdominal cramps, with or without diarrhea
- Regular or frequent contractions or uterine tightening, often painless
- Ruptured membranes (your water breaks with a gush or a trickle of fluid)
- See a specialist if you have a history of preterm birth or complications in your pregnancy
If you have had a preterm birth in the past, it’s important to see a high-risk pregnancy specialist, ideally before you become pregnant, to discuss your particular situation and the types of strategies to decrease your risk of recurrent preterm birth.
What does the future look like for preventing preterm birth?
We need to think about preterm birth not as a diagnosis, but rather one possible outcome of a variety of different causes and processes. We need to follow the successful path of our cancer colleagues.
Before the 1950s, “cancer” was considered a singular diagnosis, and treated similarly with surgery, chemotherapy and radiation, no matter where or how it occurred in the body. But today, through the use of imaging biomarkers like those identified with PET or CT scanning combined with fluid biomarkers found in blood or urine or the tumor itself, we understand that there are thousands of different types of cancers, and the approach to treating them should be individualized to a specific tumor in a specific patient at a specific point in time.
This involves understanding the internal (for example, genetic) and external (for example, environmental stressors) environment of a person. This is called precision (or personalized) medicine, and it’s why now the previously unthinkable has become true – some cancers are curable!
Could understanding a patient’s genetics and environmental factors help doctors determine what might help prevent preterm birth in a certain patient?
This is where we are slowly starting to go with preterm birth.
One of our maternal fetal medicine doctors at Intermountain, Dr. Sean Esplin, recently led a nationwide study looking at an imaging biomarker (length of cervix measured by ultrasound) and fluid biomarker (presence of fetal fibronectin in the vagina) related to preterm birth. More than 9000 women were evaluated, and the study showed that even the combination of these two biomarkers did not effectively predict preterm birth.
However, more importantly, it told us we need more, and better, imaging and fluid biomarkers to direct their therapies. What will happen from further investigations is we will have many more biomarkers so we can develop new therapies and target them to a particular person in a particular pregnancy. When we are able to do that, we will undoubtedly have the same sort of success as our oncology colleagues – and the previously unthinkable will happen – a cure!
Decades ago, nobody thought cancer would actually be curable, but today we know that several cancers are actually curable, or at least can be managed as chronic diseases. This is where we can go with the problem of preterm birth!
For more information: Go to https://intermountainhealthcare.org/ and search for high risk pregnancy or maternal fetal medicine.
The Baby Your Baby program provides many resources for all pregnant women and new moms in Utah. There is also expert advice from the Utah Department of Health and Intermountain Healthcare that air each week on KUTV 2News.