Preterm Birth Screening
Posted on 7th December 2018 at 20:32
Preterm or premature birth is when a baby is born before 37 weeks of pregnancy. In the UK, around 1 in 10 babies are born preterm. Most obstetricians and neonatal doctors will be more concerned when the premature birth occurs before 34 weeks and certainly before 32 weeks of pregnancy (very preterm). This is because the earlier the baby is born, the higher the risk of long term complications or health concerns for the baby.
Why is Preterm Birth a concern?
Preterm or premature babies can have difficulties with their long term health because their lungs, bowel or brain may not have had time to mature and so not work as well. With support from the neonatal (baby) doctors, many premature babies will grow, develop and can catch up. Neonatal care has improved in recent years, so overall outcomes are better than before.
Can a Preterm Birth be predicted?
In women at high risk of preterm birth, there are methods available that can help to predict if a premature birth will happen again.
This starts with checking a medical history to gather information about what has previously happened and measuring the length of the cervix or neck of the womb.
A woman may be at risk if she has had a previous preterm baby before 37 weeks, her waters have broken before 37 weeks, she has had a late miscarriage or pregnancy loss between 16 and 24 weeks of pregnancy. Having had one or more operations on the cervix where some of the cervix has been removed may also increase the risks of preterm birth.
How is the risk of Preterm Birth assessed?
In women at high risk of preterm birth, there are methods available that can help to predict if a preterm birth will happen again. This starts with checking a medical history to gather information about what has previously happened and measuring the length of the cervix or neck of the womb. A woman may be at risk if she has had a previous preterm baby before 37 weeks, her waters have broken before 37 weeks, she has had a late miscarriage or pregnancy loss between 16 and 24 weeks of pregnancy. Having had one or more operations on the cervix where some of the cervix has been removed may also increase the risks of preterm birth.
To assess the risk of preterm birth, the length of the cervix is measured by a transvaginal ultrasound scan and a normal cervix measures more than 25 mm long. When the cervix measures less than 25 mm, it is described as short and the woman will be at risk of a preterm birth.
Preterm birth clinics that do this risk assessment are available in some NHS hospitals but not all. So the management will vary depending on where a woman lives and her local hospitals policies. Also, preterm clinics have been shown to be good at reducing the number of preterm births in some hospitals in the UK.
How is a short cervix managed?
If a cervix is short, there are treatment options. A woman may be offered a cervical cerclage. This is where a stitch is put around the cervix to try and stop it from opening or offered vaginal progesterone pessaries, a hormone that has been found to reduce preterm birth in 3 to 4 out of 10 women. The National Institute for Health and Care Excellence (NICE) provides national guidance have has recommended that women who have had a previous preterm birth or late miscarriage and have a cervical length of less than 25 mm measured between 16 and 24 weeks of pregnancy are offered a choice of either vaginal progesterone or prophylactic cervical cerclage.
Having a cervical length scan may is useful but it is not available in all hospitals. At the Aster Baby Scan clinic, we can measure the length of the cervix and will refer you to your healthcare provider if any concerns are present.
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