C-sections may increase an infant’s risk of developing asthma, diabetes, and obesity, according to a new report by the Institute of Reproductive and Child Health in Beijing.

When analyzing past research, report authors Dr. Jan Blustein and Jianmeng Liu found 23 studies linking Cesarean births to asthma, 20 linking them to type 1 diabetes, and 9 linking them to obesity.

However, if a link exists, the difference doesn’t seem to be huge. 9.5% of children born via C-section develop asthma, but so do 7.9% of children born vaginally. Still, it’s a difference worth noting.

But what causes the difference is up for debate. One theory is that healthy bacteria are passed to the infant during vaginal birth. Another is that hormones released during natural birth help minimize an infant’s risk. Another is that the health problems that make a C-section necessary in the first place are passed onto the child, and the process of birth doesn’t actually affect anything. But right now there simply isn’t enough data to know which theory, if any, is correct.

Of course, C-sections can be life-saving for both mothers and children, and neither Blustein nor Liu view them as a bad thing. They simply feel the increased risk factor should be taken into consideration in cases where C-sections are elective. According to Dr. Blustein, “It’s a discussion that’s important to have in view of the rising rate of C-sections. The magnitude of risk elevation is small, but even when we are talking about increasing the risk modestly, we still need to talk about it.”