Prevention & Treatment

Can Preterm Birth be Predicted?

Preterm Birth occurs in 8 – 10% of all pregnancies.

However, two important factors determine whether that risk is increased in a particular patient. These are:

A. History of Preterm Birth: • A patient with a history of one previous preterm birth has a 10 – 20% chance of delivering prematurely again.
• A patient with a history of two or more previous preterm births has up to a 40% chance of delivering prematurely again.

B. Cervical length:
The length of the cervix is measured by transvaginal ultrasound as of 12 weeks gestational age.
The following measurements for cervical length have been suggested:
Longer than 2.5 cm: there is a ~97% chance of delivering full-term.
Shorter than 2.5 cm: there is a ~40% chance of delivering prematurely.
Shorter than 1.5 cm: there is a ~50% chance of delivering prematurely.

Note that serial progressive shortening of the cervix with time is more reliable than a single measurement.

Can Preterm Birth be Prevented?

Many strategies have been suggested to promote a healthy pregnancy and increase the pregnancy’s duration.

1. Good Nutrition:
A well-balanced diet is an important part of a healthy pregnancy. Suggestions for healthy eating are outlined later in this book.

2. Quitting Smoking:
Smoking during pregnancy has been shown to increase the risks of delivering a baby preterm. Methods to help you quit smoking are discussed later in this book.

3. Modified Activity:
If you are at risk of delivering your baby early, your doctor may recommend that you rest at home. This option is discussed later in this book.

4. Infections:
Screening for and treating vaginal and urinary tract infections have been shown to decrease the risk of preterm birth.

The antibiotics used to treat these infections are SAFE FOR USE IN PREGNANCY.

5. Cerclage:
This method involves stitching the cervix closed, either as a preventative procedure early in the pregnancy or as an emergency procedure during the pregnancy.

There are two types of Cerclage:

A. Vaginal Cerclage:

a) McDonald Cerclage: the stitch is placed around the neck of the cervix, at the top of the vagina, like a purse string.

b) Shirodkar Cerclage: the stitch is placed through the walls of the cervix like a noose.

Both of these procedures achieve the same effect.

B. Abdominal (Cervico-Isthmic) Cerclage:

The stitch is placed, by laparotomy (through an abdominal incision) or laparoscopy (using a telescope) or by vaginal dissection at the junction between the cervix and the uterus like a purse string.
This stitch is indicated only in patients with:
• An absent vaginal portion of their cervix
• A previously failed vaginal cerclage

This stitch is permanent, and requires the patient to deliver by Cesarean Section.

Cerclages may not be appropriate for everyone and may not prevent all cases of preterm birth. Talk to your doctor about whether a cerclage is right for you.

6. Drugs to Treat Preterm Labour

Contractions of the uterus that open the cervix may be treated by certain medications.
The most commonly used are:
• Indomethacin (Indocid TM)
• Nifedipine (Adalat TM)
• Trinitryl glycerine (Nitro Patch TM)

These medications are useful in slowing labour. This is important in order to:
• transfer the mother to a high-risk centre
• give the mother steroid (Celestone TM) help the baby’s lungs develop.
These medications may also help relieve a uterus that is irritated and contracting, but not in true labour.

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Approach to the Prevention of Preterm Birth and Care Plan

Special Pregnancy Program

Referrals »

Fetal Medicine: 416-586-4800 x 7756
Fax: 416-586-3216

Maternal Medicine: 416-586-4800 x 7000
Fax: 416-586-5109

Main clinic hours: Monday to Friday, 8am to 4pm

Prenatal Diagnosis & Medical Genetics

Referrals »

phone: 416-586-4800 x 4523
fax numbers:
416-586-4723 or 416-586-8384

Perinatal Mental Health

Referrals »

Phone: 416-586-4800 x 8325
Fax: 416-586-8596