Subjects will be divided into two groups, the normal ovarian reserve group and the poor ovarian reserve group according to AFC. Poor ovarian reserve is defined as an AFC of less than 5, while normal ovarian reserve is defined as an AFC of 5 to 15 based on a previous study showing AFC being a good predictor of ovarian response (Tomas 1997). Subjects with normal ovarian reserve will be further subdivided into <35 and >/=35 years old while subjects with poor ovarian reserve will be further subdivided into first or subsequent cycles of IVF for subgroup analysis.