Mothers with hepatitis B are not more likely to infect their newborn by breast-feeding so long as their child has been properly vaccinated for the disease, a new study by Fudan University suggests.

Fudan University's School of Public Health released its study in London's journal BMC Public Health last month, saying that the risk of infection, no matter the severity of the disease among mothers, was nearly the same between babies who were breastfed and those given milk powder.

The school analyzed 36 studies conducted by medical experts in various countries, including China, the US and Italy, which comprised some 5,650 samples from babies whose mothers suffer from hepatitis B. The vaccinated babies were split into two groups: one was breast-fed and the other received milk powder.

The Fudan study showed that 4.2 percent of the 2,717 babies, who were breast-fed by mothers with the disease, contracted hepatitis B later in life, while 4.4 percent of the 2,933 babies, who were given milk powder by their mothers with the disease, still got hepatitis B when they were older.

"The results show that the risk of infection remains similar for babies who are breast-fed, and for those who are not," Zheng Yingjie, lead researcher of the study, from Fudan University, told the Global Times Monday.

"For the babies that were given milk powder, it remains unclear as to how they contracted the disease later in life," he said. "But they likely transmitted the disease through other channels, such as sexual intercourse."

Mother-to-infant transmission, blood transmission and sexual transmission have long been regarded as the main channels for contracting hepatitis B, but vaccination has played a big role in preventing babies from getting the disease since the 1990s, said Zheng.

"Before the 90s, about 90 percent of babies, born from mothers with serious cases of hepatitis, were infected with the disease later in life," he said. "But this number dropped to just five percent after the vaccinations started being used a couple of decades ago on the Chinese mainland.

"Besides, most of the 5 percent who are infected, contract the disease in their mother's womb, before they can be given the vaccination," he added.