But researchers did find children of snoring mothers were more likely than other children to need additional hospital treatment in their first six years.
"Our study shows without a doubt that maternal sleep apnoea during pregnancy is associated with poorer childhood health," said lead researcher Yu Sun Bin.
The first step in addressing the problem was to identify sleep apnoea in pregnant women.
Better diagnosis and treatment of pregnant women with obstructive sleep apnoea could help protect their children from health problems in the early years of life, said Bin.
There was also a possibility the maternal apnoea put a child's intellectual ability at risk but this would need further study.
"Until more studies done, mothers with sleep apnoea should be reassured that their kids are not worse off," Bin said.
The next step was to have a large scale systematic screening of all mothers for sleep apnoea to gauge the extent of the problem.
At this stage they did not know why the reading ability was affected.
She said researchers had been left "very confused" by the reading result and said it needed further exploration in future studies.
Bin said the groundbreaking study had thrown up many questions regarding sleep apnoea and pregnancy including whether it was triggered by the growing womb.
If a mother was pregnant and knew she suffered from the sleep disorder Bin advised her to seek medical advice.
"It's important not to worry. Speak to your obstetrician and see what treatment options are there for you."
Sleep specialist Dr Stuart Jones called the findings "fascinating".
It was fairly common knowledge the sleeping disorder wasn't good news for the health of pregnant women, he said, but it was surprising the issue affected the cognitive development of their child.
The Counties Manukau District Health Board doctor recommended maintaining a healthy weight and being mindful of sleeping positions as ways to combat sleep apnoea.
"Research showed that people are more likely to snore if they're on their back rather than on their side," he said.
Jones said the results linked into the results of other studies which highlighted a link between habitual snoring throughout childhood and poor academic performances.