Preterm labour can complicate about 10% of
pregnancies. It refers to regular contractions with changes in the cervix prior to 37+0 weeks
of gestation. Preterm labour can result in a very premature baby – but if recognized
early, interventions can be done to lower the risk to the baby. Here are some important things that you need
know about diagnosing preterm labour: When I take a history in a woman with suspected
preterm labour, here are some important questions I ask: Is there a prior history of spontaneous preterm
labour? At what gestational age? This is the most important risk factor for preterm labour.
What is the current gestational age and how was this determined? Accurate dating is important
to determine management and prognosis for the fetus.
When did the contractions start and how painful are they? Is there any vaginal bleeding? Significant
pain may be an indication of placental abruption or uterine rupture. Significant bleeding can
be concerning for placental abruption, placenta previa or vasa previa.
Is there any fluid leakage? A common cause of preterm labour is preterm rupture of membranes.
Consider the colour of the fluid – amniotic fluid is clear while green fluid is suggestive
of meconium and fetal distress. Is there fetal movement? This is important
in assessing fetal well being. When examining the patient, here are some
important things to remember: Start with a sterile speculum exam. Lubricate
the speculum with saline to visualize the cervix and swab the posterior fornix for the
fetal fibronectin test. Fetal fibronectin test has a good negative predictive value
for preterm labour. Transvaginal ultrasound is helpful to assess
cervical length. A cervical length>30mm has a high negative predictive value for delivery
prior to 34 weeks of gestation. A cervical length