Definition of "Preterm birth"

Last modified: 11 hours

Preterm birth (aka premmies) is where a baby is born 34-36 weeks gestation. The cause of preterm birth is often unknown, but there are risk factors associated. TPL is short term for threatened preterm labor.

  • Uterine contractions, which occur more often than every 10 mins
  • Leaking of fluid from the vagina

Patient information

How do you know a preterm birth is happening?
When childbirth starts, at or before 36 weeks.

How do you know chidlbirth is starting?
Uterine contractions more often than every 10 minutes indicates labor has started. Alternatively, there may be rupture of membranes, which causes a gush of fluid to come out from the vagina.

What is the membranes?
It's the amniotic sac that cushions and surrounds bub.

  • After the 42nd week of gestation, the placenta, which supplies the baby with nutrients and oxygen from the mother, starts aging and will eventually fail
  • Cause unknown
  • Artificial induction for medical reasons for early delivery, including preeclampsia

Patient information

Why would a baby pop out at or before 36 weeks?
There might be a medical reason, such as impending seizure, which we call preeclampsia. We don't really know why it happens naturally, but there are risk factors we've identified.

Risk factors
  • Diabetes
  • Hypertension
  • Being pregnant with more than one baby
  • Being either obese or underweight
  • Number of vaginal infections
  • Tobacco smoking
  • Psychological stress

Patient information

What are these risk factors for bub coming out at or before 36 weeks?
High blood glucose, which we call diabetes. High blood pressure. Having twins, triplets, and so forth. Being overweight or underweight. Vaginal infection. Smoking. Just being stressed out.

  • Preterm, is 34-36 weeks. These weeks must be completed, so if it is 36 weeks+6 days, it is technically still late preterm
  • Prematurity (aka premature birth), is <34 weeks, where a baby is born before developing organs are mature enough to allow normal postnatal survival, and as such, are at greater risk for complications, including disabilities, and impediments in physical and mental development. NICU units only handle premature babies, i.e. <34 weeks
  • Extreme prematurity is <28 weeks
  • Premature birth is <34 weeks. Previable is <24 weeks

Patient information

Full term. Early term. Preterm. Premature. I hear these terms flying around. What exactly do they mean?
Full term is 39-40 weeks. Early term is 37-38 weeks. Preterm is 34-36 weeks. So the range of parameters from normal going extreme downwards, are 2 weeks (39-40), 2 weeks (37-38), 3 weeks (34-36), and then under that (<34).

So going back to preterm. What is it?
40 is normal. Well, 39-40 is normal. 37-38 is normal. But NEITHER of these are preterm. Preterm is the extreme situation of 34-36 weeks.

What is it when it's <34 then?
That's prematurity. Premature is when a baby is born before developing organs mature enough to allow normal postnatal survival, and it is only through modern medicine that they can actually survive !

How about <24 weeks?
Previable. In between premature and previable is <28 weeks, which is extreme prematurity.

  • PAMG-1 (placental alpha microglobulin-1), a biomarker that is the best single predictor of imminent spontaneous delivery within 7 days of a Pt presenting w/ Sx of preterm labor
  • Fetal fibronectin (fFN), a biomarker in cervical/vaginal secretions, indicating the border between the chorion and deciduas hs been disrupted. It indicates an increased risk of preterm birth
  • Cervical U/S, with a short cervix preterm undesirable, as it infers an advanced Bishop score
  • Prevention, in those at risk, w/ the hormone progesterone, if taken during pregnancy, may prevent preterm birth. There is limited evidence supporting this however
  • Avoid preterm birth (even early term birth) if possible. Only deliver preterm by labor. Thus, do not induce (including C-section)< 39 weeks, unless required for other medical reasons
  • Tocolytics, including nifedipine, may delay delivery for several days, so a mother can be moved to where more medical care is available, and the corticosteroids have that 1-2 day window to work
  • In prematures (<34 weeks, but usually >24 weeks), corticosteroids improve outcomes
  • Bed rest is NOT useful
  • Once the baby is born, care includes:
    • Keeping the baby warm through skin to skin contact
    • Support breastfeeding
    • Tx infections
    • Supporting breathing

Patient information

I think I have some of the risk factors for preterm birth, and I think it's going to pop out early. What might the doctor do?
We can give the hormone progesterone, although there is limited evidence supporting this. But whatever we do, we do not induce. Or C-section. Unless if there's good reason to. We don't want to "intentionally cause" preterm birth (34-37 weeks) - or even early term birth (37-38 weeks).

I've done the preventative thing, but it doesn't work. The baby is about to come out . What to do?!!
We give a drug that will try to stop contractions, nifedipine. This only gives us several days. But that's enough to allow us to make plans. And particularly, in premature babies, that is, those who are <34 weeks, corticosteroids.

Why do we give corticosteroids? Do they have asthma?
No. They don't have asthma... Well, we hope they don't . We give corticosteroids because it helps super-speed up their lung development.

  • It can carry risks for both the mother and the infant, including fetal malnutrition
  • Increased risk, especially the earlier a baby is born, of:
    • Cerebral palsy
    • Delays in development
    • Hearing problems
    • Problems seeing
  • 75% of preterm infants are expected to survive with appropriate Tx

Patient information

What's it like in the long term to be born at or before 36 weeks?
Remember that the baby develops in the womb. So if it's outside, it doesn't get that opportunity. So they can have delays in development. And they can have problems with the major organs, like with the brain as in cerebral palsy. Problems hearing. Problems seeing.

How many survive?
Modern medicine is magical. Wow. That was a lot of M's. Real alliteration there. Anyway, 75% will survive with appropriate treatment.

  • If the fetus passes meconium (its fecal matter), which is not typical until afterbirth, and breathes it in, it could become sick with meconium aspiration syndrome
  • Progress has been made in the care of premature infants
  • There has bene no progress in reducing prevalence of preterm birth
  • Preterm birth is the most common cause of death in infants worldwide
  • 40% of pregnancies are unplanned, and up to 50% of those are actually unwanted. Of unplanned pregnancies, 60% of women used birth control to some extent during the month pregnancy occured
  • In many countries, rates of premature births have increased between the 1990s and 2010s
  • 15 million babies are born preterm annually, in 12% of all deliveries
  • Premature births have increased
  • Complications from preterm births have decreased
  • Complications from preterm births, results in 740k deaths annually
  • The chance of survival at <23 weeks is close to 0, at 23 weeks is 15%, at 24 weeks is 55%, and at 25 weeks is 80%. The chances of surviving without long term difficulties is less
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Definition of Preterm birth | Autoprac

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