Netballer finds birth like mother of all marathons

Former Silver Fern Tania Dalton felt as though she had run five marathons after giving birth for the first time.

Dalton, who made headlines when she continued to play netball while pregnant, had believed being fit would make her labour easier. It didn't.

The contractions that started one Sunday lunchtime resulted in the birth of her daughter, Tayla, more than 28 hours later.

"The labour was heinous," Dalton remembers. "I didn't have any pain relief. I thought I was pretty tough but it was the biggest pain I have felt in my life. I was shattered for about a month."

Dalton's experience fits the hypothesis put forward in research by Auckland University PhD student Jennifer Kruger.

Mrs Kruger, a midwife and nurse, studied the effect of high-intensity sport on a group of elite female athletes, including netballers, basketball players and aerobic gymnasts.

Using MRI scans, she studied the pelvic floor muscles of 10 women who had participated in high-impact sport and training for at least five years and had reached a national or international standard. They were still active in their sport at the time of testing.

When the findings were compared with data from 10 similar-aged women who were not athletes, she found that the athletes had significantly bigger pelvic floor muscles.

Mrs Kruger said that could play an important role in the second stage of labour because the muscles needed to be able to stretch and relax to allow the baby's head through the birth canal.

"If the muscular complex has changed in any way, either become less compliant or increased in muscle mass, as is evident with elite athletes, the ability of the baby to make progress may be compromised."

That could result in a lengthy second stage of labour and increased risk of incontinence.

Mrs Kruger said it appeared that high-impact sports such as netball and aerobics, which required constant jumping and bracing, caused the muscle changes. But activities such as pilates, which concentrated on "core stability work", also consistently activated those muscles.

Mrs Kruger said it was difficult to say how much exercise was good for pregnant women. Research had found that women who did moderate-intensity exercise before and during pregnancy had shorter labours and potentially easier deliveries than women who were sedentary.

Dalton, who reduced the amount of abdominal exercise she did while pregnant, was still swimming five times a week, running about three times a week and doing team training before Tayla was born.

"I was jumping higher and running faster than I ever was before. I did my best fitness test ever while pregnant."

She recently gave birth to her second child, Charlie, and this time it was much easier.

Karen Guilliland, national director of the NZ College of Midwives, said it was impossible to generalise about how a woman's labour would go based on fitness. "Like all life processes it depends on the context and person."

Ms Guilliland said pregnancy was not the time to start a new fitness regime, but provided a woman felt comfortable she could continue her previous exercise routine.

Mrs Kruger now plans to extend her research to study two groups of elite athletes aged 18 to 36. The first group would include athletes pregnant with their first baby and the second those who had never been pregnant. A 3-D ultrasound will be used to study how the pelvic floor muscles function.