Twins should be delivered at 37 weeks to minimise the chance of a stillbirth, researchers have found.

A study in The British Medical Journal (BMJ) found that 37 weeks is optimal gestation length for twins to minimise stillbirths and newborn deaths.

Furthermore, the researchers found no clear evidence to support routine delivery before 36 week’s gestation.

The risk of stillbirth is known to be higher in twin pregnancies than in pregnancies with just one child.

Therefore, uncomplicated twin pregnancies are often delivered early in an attempt to prevent stillbirth.

However, the optimal gestational age for delivery that minimises risks to newborns was not known.

Current recommendations vary on the timing of delivery, starting from 34 up to 37 weeks’ gestation in twin pregnancies where the babies share the same placenta, and from 37 up to 39 weeks in twin pregnancies where they have two individual placentas.

The researchers analysed the results of 35,171 uncomplicated twin pregnancies, within the past 10 years, with reported rates of stillbirth and instances where the child died up to 28 days after delivery.

In all cases the pregnancy lasted more than 34 weeks.

The researchers looked specifically at the balance between the risk of stillbirths from expectant management, also known as “watchful waiting”, and the risk of neonatal death from delivery beyond 34 weeks.

They found that, in pregnancies with two placentas, the risk of stillbirths and neonatal death were the same until 37 weeks’ gestation.

However, delivery at 38 weeks led to an additional 8.8 deaths per 1,000 as a result of an increase in stillbirths.

In pregnancies with one placenta, the risk of stillbirth appears to be higher than neonatal death beyond 36 weeks’ gestation.

But more data are needed to make a clear recommendation on best time to deliver these types of pregnancies.

Rates of neonatal morbidity and admission to the neonatal intensive care unit showed a consistent reduction when increasing gestational age in both types of pregnancies.

Based on these estimates, the researchers suggest that, for twin pregnancies with two placentas, delivery should be considered at 37 weeks’ gestation “to prevent the significant increase in stillbirths associated with expectant management compared with the risk of neonatal deaths associated with early delivery”.

The study concludes that this information “will complement the ongoing national and international efforts to reduce the rates of stillbirths and unexpected neonatal complications in babies born near term”.

Speaking at NHS Expo today about the study, Simon Stevens, chief executive of NHS England said the findings were “huge”.

He said: “That’s research that’s been available across the world for at least a decade and that’s just looking at the records of 35,000 pregnancies.

“The NHS supports 670,000 women to give birth each year. Imagine what we can do to improve the quality of care by harnessing the insights from these kinds of real world data.

“But in order to do that we need the clinical infrastructure at hospital level, linked interoperability with what’s happening in general practice.”