Pregnant women coached through their first delivery do not fare much better than those who just do what feels natural, according to a study released on Friday.

Researchers at the University of Texas Southwestern found that women who were told to push 10 minutes for every contraction gave birth 13 minutes faster than those who were not given specific instructions.

But they said the difference has little impact on the overall birth, which experts say can take up to 14 hours on average.

"There were no other findings to show that coaching or not coaching was advantageous or harmful," said lead author Dr. Steven Bloom, the interim head of obstetrics and gynaecology at the Dallas-based university.

"Oftentimes, it’s best for the patient to do what’s more comfortable for her," he added.

Bloom and his team studied 320 first-time mothers who had simple pregnancies and did not receive epidural anaesthesia.

About half were given specific instructions by certified nurse-midwives during the second stage of labour, when they were fully dilated. The rest were told to "do what comes naturally."

On average, coached mothers trimmed the final stage to 46 minutes compared to 59 minutes, according to the study sponsored by the National Institute of Child Health and Human Development at the National Institutes of Health.

Women in both groups experienced about the same number of forceps use, Caesarean deliveries and skin tears, among other complications.

The results were published in the January issue of the American Journal of Obstetrics and Gynaecology.

Less clear was whether extra pushing encouraged by a coach could lead to bladder trouble.

In an earlier study, the researchers tested bladder function in 128 of the mothers three months later.

While such problems usually resolve on their own over time, women who had been coached had a smaller bladder capacity and felt the urge to urinate more often, they previously found.

Senior author Dr. Kenneth Leveno, a professor of obstetrics and Gynaecology at the school, said it was still not clear if the bladder problems could lead to long-term complications and more studies are needed.

"We don’t want to alarm patients about this," he said.

Friday’s finding that coaching "confers neither benefit nor harm might be pre-empted if it is confirmed that coaching has deleterious long-term effects," the study concluded.

More here.