There is a lot of gambling features involved in pregnancy. The probability of having a girl or a boy is pretty much 50/50. However, in the US the ratio shows that there are 51% boys and 49% girls. Previous experiences do not affect future ones; probability has no memory. Thus the probability of having a girl next is 50%, regardless of if you’ve had boys or girls in the past. To think otherwise is known as the gambler’s fallacy. In the US parents are 6% more likely to stop having children if the first two children are a boy and a girl. From parents with two same-gender children, those with two girls are 3% more likely to stop having children than those with two boys. Parents of 3 same-gender children are only 2% more likely to have a 4th child than parents with mixed-gender children. Even after 3 boys, you are only 6.4% more likely to have a 4th boy than a girl. If you have had 2 or 3 boys, you are only about 2% to 6% more likely to have another boy. If you have had girls, you are slightly more likely to have a boy next.