Fish diet is healthy; at least, that's what we are taught. However, a new study suggests that eating too much fish when pregnant may raise the child's obesity risk.

Previous reports suggest that pregnant moms should consume more fish because it lowers their baby's risk of autism and improves the child's cognitive scores. Latinos Health previously reported that consuming fish when pregnant makes the babies smarter. Unfortunately, a new study seems to show otherwise -- in a different aspect.

According to Los Angeles Times, newborns with mothers who ate fish for more than three times a week grew faster in the first two years. Moreover, they were likely to be overweight or obese when they reach 4 and 6 years old.

The researchers believed that there were two explanations for their findings. First, the omega-3 fatty acids that were abundant in fish might have predisposed fetal stem cells to differentiate into fat cell. Second, it could also be the pollutants found in fish that disrupted the fetal hormones related to metabolism and prompted the storage of more fats.

The team of researchers, which is led by Leda Chatzi, M.D., Ph.D., of the University of Crete, Greece, analyzed data from 26,184 pregnant women and their children in European and U.S. studies to examine potential link with maternal fish intake and childhood growth, overweight or obesity. The children under the study were followed until they were 6-years old.

They learned that expectant moms with high consumption of fish or who ate fish more than three times a week gave birth to children with high BMI, Science Codex has learned.

High maternal fish intake during pregnancy was also associated with rapid growth from birth to two years and with increased risk of overweight/obesity for children at ages 4 and 6, compared to maternal fish intake of once a week or less. The magnitude of the effects of fish intake was greater in girls than boys.

"Contamination by environmental pollutants in fish could provide an explanation for the observed association between high fish intake in pregnancy and increased childhood adiposity," the authors wrote.

However, they noted that, while they consider the consumption of different fish types, their data did not include the different species, cooking procedures and the water source -- if the fish was from the river or the sea.

"Moreover, in the absence of information regarding levels of persistent organic pollutants across participating cohorts, our hypothesis that fish-associated contaminant exposure may play a role in the observed associations remains speculative," the researchers concluded.