Parents and teachers often wonder why some children perform better on academic tests than other kids. Is it the children's diet, their bookish home life, their 24-hour access to Mozart and computers? A new British study sheds some light on the age-old question by suggesting that unplanned children lag behind planned children on academic tests. Meanwhile, children born through in-vitro fertilization, or IVF, appear to perform best of all. Three key questions:

What exactly did the researchers find?
They studied data from about 12,000 kids born in the U.K. between 2000 and 2002. Children who were born after an unplanned pregnancy had verbal skills that lagged four to five months behind kids who were the result of planned pregnancies. As for children who were born after an IVF pregnancy, their verbal skills were three or four months ahead of the planned children.

Why do unplanned kids do so poorly?
Affluence levels. Researchers believe that the learning gap can be explained by socioeconomic differences between poor families and affluent ones. Children who were "born after unplanned pregnancies were more likely to have poor, young, or less-educated mothers," says Martin Beckford in Britain's Telegraph. They therefore might also have less access to educational toys and things like puzzles, books, and trips to the library. When the families' income levels were factored out of the data, the difference between planned and unplanned kids largely disappeared.

But why do kids born after IVF pregnancies do so well?
Once again, socioeconomics favor these kids. The children born after IVF procedures were more likely to have parents who can afford the expensive treatments. Besides being more affluent, these parents, the researchers found, were more likely to be older, better educated, and more involved with their kids — all factors that give children a "leg up" on their schoolmates.

Sources:, MyHealthNewsDaily, New Scientist, Telegraph