"Our findings suggest that artificially sweetened beverages during pregnancy are not likely to be any better at reducing the risk for later childhood obesity than sugar-sweetened beverages," said Cuilin Zhang, from the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD).
According to researchers, as the volume of amniotic fluid – which surrounds the unborn baby in the womb – increases, pregnant women tend to increase their consumption of fluids.
To avoid extra calories, many pregnant women replace sugar-sweetened soft drinks and juices with beverages containing artificial sweeteners.
However, the study, appearing in the International Journal of Epidemiology, found that children born to women who drank sweetened beverages were 60 percent more likely to have a high birth weight.
At age 7, children born to mothers who drank an artificially sweetened beverage daily were nearly twice as likely to be overweight or obese.
Consuming a daily artificially sweetened beverage appeared to offer no advantages over consuming a daily sugar-sweetened beverage.
Conversely, women who substituted water for sweetened beverages reduced their children's obesity risk at age 7 by 17 percent, the researchers observed.
For the study, the team analysed data from more than 900 pregnancies that were complicated by gestational diabetes, a type of diabetes that occurs only during pregnancy.
Previous studies conducted in animals associated weight gain with changes in the types of bacteria and other microbes in the digestive tract
Others suggested that artificial sweeteners may increase the ability of the intestines to absorb the blood sugar glucose, the researchers said.