Study design and sample size This was a randomized clinical trial involving ninety patients who were undergoing conventional IVF or intracytoplasmic sperm injection (ICSI) treatment at our Reproductive Medical Center. The subjects were recruited and studied for a period of 6 months between January and June 2008. The study was approved by the Ethics Committee of Shen-Zhen Maternity and Child Healthcare Hospital. Subjects all signed an informed consent form.