The Odds of Having a Baby Girl After Two Baby Boys

Sure, you’ll love them just the same no matter what sex they are. But the fact of the matter is that most parents planning to have more than one child, given the choice, would opt for at least one of each sex. While science has not progressed to the point where you can select in advance the sex of a baby, statistics are available to help determine the odds of whether you’ll have a girl or a boy.

Breaking the Law of Averages

In theory, a couple has a 50 percent chance of having a boy and a 50 percent chance of having a girl 1. And since you're tossing a new roll of the dice every time, those odds should remain the same with each new conception. But that’s not reality. In the U.S., 51 percent of all babies born are boys. Although medical experts have yet to pinpoint an explanation for this phenomenon, some believe male-producing sperm are faster than female-producing sperm, giving them a slight advantage in the race to fertilize an egg. Regardless of the reason, based on actual percentages, any couple’s odds of having a boy are slightly greater.

The Male Majority

Although the law of averages says the odds of having a boy or a girl should be about equal every time, again, reality paints a slightly different picture. Commonly a couple who wants a mixed sex family thinks they’re “due” to have a girl after having boys on the first two or three attempts, but statistics show the odds actually decrease with every male birth. A couple who already had two boys has a 47.7 percent of having a girl on their third try. After three boys, the odds of having a girl drops to 43.6 percent.

The Weaker Sex

The same law of averages doesn’t apply to families whose first child is a girl, however. Whereas a graph depicting the odds of having a girl after each consecutive boy would show a steady decline, a graph detailing the opposite would look more like the layout of a child’s roller coaster. A couple who already has a girl has a slightly better chance of having a boy the second time around, with just 45.5 percent of parents following a firstborn girl with a second. However, if a couple beats those odds and has two girls, their chance of having a third rises to 54 percent. And anyone who’s brave enough to take a fourth shot at having a boy will find the odds to be slightly more favorable: After three girls, the chance of having a fourth drops to 47.3 percent.

Changing the Odds

There may be no scientifically proven methods of selecting the sex of a child, but some people believe there are ways to influence whether a baby will be a boy or a girl. A study conducted in Holland determined that women who eat a lot of food that’s high in calcium and magnesium — such as milk, almonds, broccoli and yogurt — have a stronger chance of giving birth to a girl. Another theory maintains that conceiving two or three days before ovulation increases the odds of having a baby girl. Still another claims that shallow penetration during conception increases the odds of having a girl because male-carrying sperm dies off quicker than the female carrying variety — so the longer the trip, the lower the chance the male-carrying sperm will complete the journey.