The position of a woman’s caesarean section scar in relation to their cervix has a bearing on the chance of having a subsequent premature birth, it's been claimed

Everyone working in maternity services is concerned about ­rising numbers of caesarean sections. More than 25% of all deliveries in the UK happen this way.

Furthermore, up to 20% of in-labour caesarean sections (CS) occur late in labour, which could affect up to 20,000 women each year. In some maternity units, CS has reached 40% of births, which means sections in the late stage of labour are also increasing.

The trouble is that women who have a CS in the late stages of labour are at increased risk of having a prem baby in future pregnancies. But UCL researchers have found a way to prevent this from happening.

The team studied 243 pregnant women between January 2017 to April 2021, who’d previously had a late-stage c-section, which can increase the risk of preterm birth in subsequent ­pregnancies from 2% to 15%.

So what is a preterm birth?

It’s one that happens before 37 weeks of ­pregnancy. There were around 53,000 babies born ­prematurely in 2021 in the UK. And in England and Wales, 7.6% of births were preterm – an increase from 7.4% in 2020. It turns out that the position of the women’s c-section scar in relation to their cervix – the neck of the womb – is crucial and the team used ­transvaginal (internal) ­ultrasound to assess it.

If the scar was low down the womb or within the cervix there was a much higher chance of the cervix becoming short in mid-pregnancy and of women delivering preterm.

To prevent this from happening, the researchers found placing a small stitch around the cervix lowered the risk of preterm birth to 4.1% in their patients. The stitch can be placed as a day-case procedure with excellent outcomes.

Author and obstetrician Professor Anna David, of UCL, said: “Caesarean sections are low risk if you have one in early labour or before labour starts. But couples and midwives need to be aware of the risks of having a c-section in the late stages of labour particularly at full dilatation.”

Generally speaking, the earlier a child is born, the higher their risk of problems. And around one in 10 of all preterm babies will have a permanent disability such as lung disease, cerebral palsy, blindness or deafness.

Professor David encourages the routine assessment of c-section scar position which takes only an extra minute to perform during a ­transvaginal ultrasound.

“If, from doing this, we can identify women with a short cervix and put a stitch in place, it reduces the risk of preterm birth massively and improves outcomes for both mother and child.”