not necessarily. It depends on whether your period is normal or not. If your period is 28 days or so, it is likely that underweight and low body fat will not affect ovulation and will not reduce your chances of getting pregnant.
Women need to consume at least 17 percent of their body for natural ovulation. When the body’s fats are too low, this disrupts the flow of hormones from the brain to the pituitary gland that urges the ovaries to release the egg. So even if you have a lot of healthy eggs, you will not be able to get pregnant because you did not go to the womb.
If you do not get your period regularly, your doctor will suggest that you take more nutrients to increase body fat. Do not pray for me to suit your weight for any length, regularity and menstrual cycle again.
But there is another good reason why you should increase your weight at any normal rate – that women who begin to carry weight are at increased risk of having a low-weight baby.