Preterm Labor: What happens? Part 1 - Dr. Pedron explains.


It will take more than one post to talk about preterm labor. This is a huge problem and the most common cause of perinatal loss.

To have a conversation about preterm birth we first need to understand some definitions. 

Though full term is generally considered to be 39 weeks gestational age, preterm birth is actually delivery less than 37 weeks

What happens between 37 and 39 weeks is also very important for your baby. We’ll talk about that another time.

What is preterm labor?

Preterm labor is defined as contractions and cervical dilation prior to 37 weeks. 

Your cervix is of course the structure between the vagina and the uterus that keeps your baby safely inside the womb. Normally it is about the size and consistency of a roll of quarters.

Contractions are what happens when the uterine muscle flexes its might. Normally contractions happen from very early in pregnancy. These might be felt as cramps. Later, as the uterus grows and the uterine muscle strengthens, women become more aware of contractions. They can be felt by placing a hand on the uterus and may even be painful. Most women refer to these as Braxton-Hicks contractions.

Fun fact; John Braxton Hicks was the 18th century obstetrician who first defined these contractions!

Unless you have cervical insufficiency, which we’ll also talk about another time, it takes a certain number and strength of contractions to dilate the cervix. When the cervix dilates, delivery may ensue.
If the muscle (the uterus, or womb) contracts when and how often it is supposed to, hopefully at term when your baby is normally supposed to arrive, that part of your pregnancy will be fine. Likewise, if the cervix stays closed, long and thick, your baby is going to stay inside until the time is right.

Let’s stop here for today. Next week we’ll pick up right where we left off and discuss some of the reasons preterm birth occurs.

Learn more about UnityPoint Clinic Maternal Fetal Medicine online or talk with your primary care provider about a referral. 

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