A trained acupuncturist applied the placebo to the same acupuncture points as for the real acupuncture.

"Placebo acupuncture is similar to acupressure and therefore is good enough to improve the pregnancy rate. Or else, it's possible that real acupuncture may, in some way, reduce the pregnancy rate of acupuncture.

"So far there is no evidence that real acupuncture would adversely affect IVF outcomes because, in a previous meta-analysis of several acupuncture studies, the pregnancy rate was higher in the acupuncture groups than in the control groups.

"Further studies should be conducted to compare placebo or non-invasive acupuncture and controls without acupuncture," Ng added.

Infertile patients can suffer from high levels of stress and anxiety, which can adversely affect the outcome of IVF.

Dr Ng said: "We found a significant decrease in serum cortisol concentration and the anxiety level following placebo and real acupuncture. Reduction in stress in both groups may also contribute to a better pregnancy rate following placebo and real acupuncture," he added.