Akira Namba, a doctor of obstetrics and gynaecology at the Saitama Medical University hospital, said that swollen breasts, a loose pelvis and, in the case of a caesarean section, damaged abdominal muscles pose a significant challenge to the returning of a sportswoman, affecting not just fitness but also balance.
"It is also quite tough to undergo full-scale training in parallel to breastfeeding," News.com.au quoted Namba, as saying.
However, Lamba said that with the modern training techniques and growing scientific awareness, many new mums are able to overcome the difficulties suggesting that childbirth boosts athletic prowess by raising the flow of androgen and other hormones.
"These athletes are professionals who knew how to control regimens and wanted to come back as soon as possible in order not to lose their value as athletes after childbirth," he said.
"Even so, post-natal tests on muscular strength and other athletic abilities have shown no particular improvements.
"But in psychological terms, a new arrival in the family can have a positive effect on the athlete's awareness," he added.
There are also evidences, which support the study.
Paula Radcliffe, who won the New York marathon in November 2007, had her first child in January.
Jana Rawlinson's returned from childbirth and won world 400m hurdles gold in Osaka in August.
Both of them said that the rigours of pregnancy and labour had improved them as athletes by giving them more confidence and even making them stronger.
"I do think it gives you an extra inner strength as well and extra balance as a person," Radcliffe said.
"This was about establishing myself to all the people who thought having a baby would be the end of my career," she said.
Patrick O'Brien of the Royal College of Obstetricians and Gynaecologists said that pregnancy and childbirth were demanding on the body so they make a person strong afterwards.
"Pregnancy and childbirth are quite demanding on the body, so going through that must make somebody stronger afterwards," he said.