If you are overweight then obese, losing measurement can boost your chances of getting pregnant. As found out thin women with lesser BMI conceive quickly than overweight women. Those who exercise daily keep their hormones in control. Increased weight can derange blood reproductive hormones. Once hormones are deranged ovulation doesn't happen and good quality eggs are not released. But a decrease in BMI to the extent of 5%-10% can dramatically improve ovulation or pregnancy rates. Obesity also has adverse effects on male fertility. Infertility related to PCOD is a common feature in bulky women. Being substantially underweight also can lead to infertility. A healthy weight with a well-planned diet and exercise is essential for a fertile life.