Pre-ovulation and post-ovulation have nothing to do with the birth of a boy or a girl; the sex of the fetus depends on the sex chromosomes of the fetus. Normally, the fetus has two sex chromosomes, one from the father and one from the mother. If the X sperm provided by the father combines with the X egg of the mother, the fetus will be female, and if the Y sperm provided by the father combines with the X egg of the mother, the fetus will be male, and the combination of such sperm and egg will be random, with equal chances of giving birth to a boy or a girl, and it has nothing to do with the preovulatory or postovulatory period. If both spouses have a sex chromosome disorder, genetic counseling can be conducted under the guidance of a medical professional to meet the need for a healthy baby and to avoid adverse pregnancy outcomes; otherwise, it is not possible to manipulate the sex of the fetus through medical means.