The chances of having a boy in the third trimester are still about 50%. The gender of the third child is not related to the gender or looks of the second child, and the chances of having a boy and a girl in each trimester are each about 50%. The chance of having a boy in the third birth is about 50%, and the corresponding chance of having a girl in the third birth is also about 50%. The human body has 23 pairs of chromosomes, of which the 23rd pair is the sex chromosome. There are two types of sex chromosomes, and the child receives one chromosome from each of his parents, the XX chromosome for girls and the XY chromosome for boys. Since the mother has an XX chromosome, she can only pass on the X chromosome to her child, while the father has an XY chromosome, so the sex of the fetus depends on whether the X or Y chromosome is inherited from the father, and therefore the chances of having a boy and a girl in each fetus are each about 50 percent. Each child is independent, and the sex of the third child has nothing to do with the sex or looks of the second child. If you need to prepare for pregnancy, please consult the obstetrics or family planning department of a regular hospital.