Threatened Preterm Labour: The Signs, the Tests and the Question of Rest

Twenty-nine weeks. Since this morning, your bump has been tightening every twenty minutes, and this time there is a pulling in your lower belly. Is it "normal" at this stage, or should you head to the maternity unit? This is exactly what doctors call threatened preterm labour, when these contractions change the cervix before 37 weeks.

The term is frightening, but threatened preterm labour is not labour: it is a warning that allows action to be taken. It does not necessarily lead to a premature birth, and every day gained counts for the baby. Here is how to recognise it, what the team will check, the possible treatments and what to make of the famous "strict bed rest".

What is threatened preterm labour?

It is the combination of uterine contractions and changes to the cervix (shortening, softening or opening) between 22 weeks and 36 weeks plus 6 days of pregnancy, counted from the first day of the last period, according to French hospital protocols. From 37 weeks, the baby is considered full term.

Premature birth is common worldwide: about 13.4 million babies were born before 37 weeks in 2020, more than one in ten, according to the WHO. Its complications remain the leading cause of death in children under 5. That is why threatened preterm labour is taken seriously, even when everything ends well. Our article on premature babies explains what happens if the birth comes earlier than planned.

Contractions before term: which signs should alert you?

Mild, painless, irregular contractions are common in the third trimester. What changes with threatened preterm labour is their regularity and intensity. Quebec's INSPQ lists as warning signs:

• regular or frequent contractions, meaning more than seven in a day;
• a "real" contraction lasting at least 20 seconds, with a bump that hardens and pain;
• heavier vaginal discharge than usual;
• a leak of clear fluid, continuous or repeated: it may be the waters starting to leak.

Bleeding is always a reason to get checked quickly: our article on bleeding during pregnancy details the causes. And to tell late-pregnancy contractions from the real start of labour, see the signs of labour.

What tests at the maternity unit?

When you arrive, the team tries to answer one question: is the cervix changing, and how fast?

• Monitoring of contractions and the baby's heartbeat (CTG), to measure how often the contractions come and check that the baby is well.
• A transvaginal ultrasound of the cervix, recommended by the French college of gynaecologists (CNGOF) because it is more reliable than a vaginal examination alone. It measures the length of the cervix. A cervix longer than 25 mm significantly reduces the risk of giving birth in the following week (Pitié-Salpêtrière protocol, Paris). Below this threshold, the cervix is described as short.
• Sometimes a fibronectin test, a vaginal swab whose value is mainly reassuring when it is negative (CNGOF).
• Tests looking for an infection, particularly a urinary one: bacteria in the urine are treated during pregnancy.

These tests help avoid two mistakes: sending home a woman whose cervix is opening, or keeping in hospital for a long time a woman whose cervix stays long and closed.

What treatments for threatened preterm labour?

Treatment depends on how far along you are, the state of the cervix and the baby's condition. It rests on three pillars, with the medicines and doses decided by the medical team.

Medicines that calm contractions (tocolytics). They delay the birth by at least 48 hours on average (CNGOF). This time is precious: it allows the injections that protect the baby to be given and, if needed, the mother to be transferred to a maternity unit equipped to care for a premature baby. Beyond 48 hours, prolonging the treatment has no proven benefit.

Steroids to prepare the baby. These injections given to the mother speed up the maturation of the baby's lungs. According to French guidelines, one course reduces newborn mortality by about 40% and hyaline membrane disease, a breathing difficulty in premature babies, by half. Their effectiveness has been shown from 24 hours to 7 days after the injection, and no benefit has been shown after 34 weeks. The WHO recommends them for women at high risk of giving birth prematurely.

Prevention for future pregnancies. In women who have already given birth too early, teams may offer close monitoring of the cervix, progesterone, a cerclage (a stitch placed around the cervix) or a pessary (a soft ring), according to Geneva University Hospitals.

Antibiotics are not given routinely: they do not reduce prematurity when there is no infection (CNGOF).

Rest: what is proven and what is not

For a long time, threatened preterm labour meant weeks lying down, or even in hospital. Practice has changed. The Pitié-Salpêtrière protocol does not prescribe strict bed rest and sees no contraindication to moderate activity: washing, going to the toilet, getting up, walking a little around the house. Hospital stays often last as long as the steroid course, then follow-up continues at home.

French guidelines also note that home follow-up after hospital does not reduce prematurity, but clearly improves how women experience this period. The "rest" prescribed is therefore mainly slowing down: sick leave, no carrying heavy loads, no long journeys, naps. The exact instructions, and the length of the leave, are set by your doctor. If you are employed, our article on your rights at work during pregnancy sets out the details.

This slowing down is often harder than it looks, especially with other children at home. This is the time to accept help from the wider family with meals, shopping and school runs. To settle comfortably on your side, a pregnancy pillow relieves the back and hips.

Preparing for what comes next, calmly

Threatened preterm labour is also a chance to check a few practical points:

• Where you will give birth: not all maternity units have a neonatal unit able to care for a baby born very early. Ask your gynaecologist and your clinic; our guide to choosing a maternity unit in Morocco lists the useful questions.
• Your hospital bag: pack it now, without waiting for the eighth month. Our hospital bag page helps you forget nothing.
• Your medical file: keep your scan reports, test results and blood group card with you.
• Twins: a multiple pregnancy carries a higher risk of prematurity, with specific follow-up (see twin pregnancy).