According to a new report, pregnant women who take acetaminophen found in popular, over-the-counter painkillers such as Tylenol and Actamin, may be boosting their baby’s risk of asthma.

The report, found in the journal Clinical & Experimental Allergy, follows six studies performed by the Medical Research Institute of New Zealand that found the use of the painkiller by pregnant women during any stage of pregnancy was linked with a 21 percent increased risk of asthma in their young children.

Although some experts say the use of acetaminophen during pregnancy has contributed to the rising rates of asthma worldwide, others say there is still no concrete evidence that this painkiller causes asthma.

In a U.S. study of 1,505 women, the use of acetaminophen did not increase the risk of asthma overall. In fact, the study showed that expecting women who used the painkiller only during the first or third trimesters were linked with a reduced risk of asthma.

Although noticeable in some instances and not in others, the link between asthma and acetaminophen is something researchers cannot yet explain. One speculation is the breakdown products of the painkiller may increase the risk of inflammation. If the inflammation affects the airway, this could increase the risk of asthma.

More studies are being performed on this link, but until solid evidence is found, experts agree pregnant women may continue taking acetaminophen.