How To Prevent Preterm Birth

Until quite recently, preterm birth has been considered to be an unavoidable and accidental consequence of pregnancy. Thankfully, those times have changed and preterm birth is now considered to be preventable, at least in a proportion of cases. Several decades of research have provided us with the knowledge to safely lower the rate of preterm birth.
In Australia 1 in every 12 pregnancies end too early – leading to more than 36,000 preterm births every year. Most children are born too early to go on to lead normal and productive lives. But for many others, there may be serious medical problems followed by life-long disability. The following preterm birth prevention interventions will be recommended for application into all clinical practices over the coming years. The Every Week Counts is also a fantasitc resource for all mothers and mothers-to-be to reduce their likelihood of experiencing a preterm birth. Read the latest edition here.

Always attend your mid-pregnancy ultrasound scan

Make sure that the length of your cervix is measured whenever you have an ultrasound scan between 16 and 24 weeks of pregnancy.  The length of your cervix in mid-pregnancy is a strong predictor of your risk of preterm birth. There are no symptoms to tell you that this may be happening. If the cervix is shortened then your doctor needs to be consulted urgently to prescribe the appropriate treatment to reduce your chance of preterm labour.

Measuring the length of your cervix

In those cases in which the cervix can be imaged clearly on the trans-abdominal scan (the routine method of scanning), a length of 35 mm or more is adequate. If the operator cannot image your cervix clearly, or if the measurement is less than 35mm, then an internal (transvaginal) scan needs to be performed. The length of the cervix on the trans-vaginal scan below which treatment is required is 25 mm. This length is less than required at trans-abdominal scan because routine (trans-abdominal) scans have a full bladder which can stretch the length of the cervix, while internal scans are performed with an empty bladder at which time the true (unstretched) length of the cervix is measured.

What if my cervix has shortened?

If your cervix is less than 25mm on an internal scan your doctor needs to prescribe natural vaginal progesterone 200mg given as a pessary. This pessary (like a simple tablet) is inserted into the vagina each night at bedtime. This treatment should continue until 36 weeks gestation and is expected to halve the risk of preterm birth. In cases in which the cervix length is less than 10mm on the internal scan, or in some cases where there is a history of previous preterm birth, the cervix may need to close surgically by the placement of a stitch. This technique is known as cerclage of the cervix and the decision requires specialist opinion and treatment.

Check if you have a history of preterm birth

Vaginal progesterone 200mg pessaries are also to be prescribed for any case in which there is a history of spontaneous preterm birth in a previous pregnancy between 20 and 34 weeks gestation. The treatment is used each night from 16 to 36 weeks’ gestation.

Make Every Week Count

No pregnancy is to be ended prior to at least 39 weeks’ gestation unless there is medical or obstetric justification. While most babies born in the days and weeks before this time can be expected to survive and live a healthy life, there are definite risks to the child being born before 39 weeks of pregnancy, including learning and behavioural problems at school age. If, however, there are risks to the pregnancy then your doctor may advise earlier birth on safety grounds.

Do not smoke cigarettes

Women must not smoke, or be exposed to cigarette smoke, during pregnancy. Smoking is a major and totally avoidable cause of preterm labour. There are excellent services available through the Western Australian Department of Health. Speak to your doctor about ways you can quit and look on-line at the Quitline website.

Get a referral to a Preterm Birth Specialist

For women at very high risk of preterm birth, you may speak to your doctor about being referred to specialists in the field of preterm birth prevention. Typically, a management plan is developed and the woman is then referred back to her referring practitioner when the high-risk period is concluded. The Preterm Birth Prevention Clinic at King Edwards Memorial Hospital in Western Australia has Maternal-Fetal Medicine specialists, ultrasound imaging facilities for cervix length measurement, and mental health care and midwifery services.

Use fertility treatments with appropriate caution

In vitro fertilisation (IVF) and ovarian stimulation increase the risk of preterm birth. Part of this increased risk results from multiple pregnancies, part results from the cause of the underlying sub-fertility, and part results from other factors that remain unclear. The Alliance recommends that fertility treatments be used with appropriate caution and applied with a full understanding of the potential to increase the risk of early birth.

Seek pre-conception counselling

Medical professionals will be encouraged to advise women to prepare for a future pregnancy by optimising their health and seeking pre-conception counselling. This is especially important for women who have an increased risk of preterm birth resulting from a personal or family history of early birth, prior surgical intervention on the woman’s cervix, or recurrent miscarriages, or those at the extremes of maternal age or where the inter-pregnancy intervals may be less than 18 months.

Other risk-minimising strategies

Other health optimising strategies will be encouraged such as the normalising of body weight, avoidance of alcohol consumption and recreational substance abuse, the taking of supplementary folate daily for at least three months before conception, the stabilisation of autoimmune conditions and the control of blood glucose levels or blood pressure in women with diabetes or hypertension respectively.