It depends on your particular circumstance. Overweight and obese women do tend to have irregular periods, and infertility seen in these cases is usually due to ovulatory dysfunction. These menstrual irregularities are thought to be due to disturbances of hypothalamic GnRH and pituitary gonadotropin secretion (i.e. FSH and LH production), and to the hyperinsulinemia associated with obesity. Hyperinsulinemia has been associated with increased circulating androgens that in turn prevents ovulation from occurring “follicular arrest”, and can effect egg quality. It can also put overweight and obese women at increased risk for pregnancy loss. Ovulation and pregnancy rates tend to improve significantly after even modest weight loss in obese anovulatory women, but it's important to note that even a small reduction of body fat (by 5-10%) can have a significant impact on reproduction in overweight and obese women.