Anything that you put in your body while your pregnant has to be researched carefully and fully to know its safety. Nothing in pregnancy can ever be considered 100% safe due to the fact true randomized control trials cannot be done on pregnant women. However, some things that seem harmless in could actually be potentially dangerous in pregnancy. A key example of this is Chamomile Tea.
Chamomile Tea is a common mild sleep aid that many people assume is safe and would not even bother to look up because of how gentle it is. However, this usually harmless tea can be very dangerous for your baby in pregnancy! To understand why we need to talk a little bit about fetal circulation.
While a baby is still inside their mothers womb they are receiving all of their oxygen through the placenta and cord. There are several adaptations in the heart that allow baby to receive and distribute oxygen before they are born. Since they are not using their lungs while in utero their lungs do not need much oxygen. One of these adaptations is an extra vessel called the ductus arteriousus. This extra valve connects the aorta to the pulmonary artery. While in uterus to shunts oxygenated blood away from the lungs (since they are not used) and directly to the rest of the body. Once a baby is born and breathing air this vessel closes.
Chamomile Tea has been linked to preterm closure of the ductus arteriousus in fetal lambs and in at least 2 cases of pregnant women. One of these cases where the vessel was seen restricted on ultrasound it reopened after she stopped drinking chamomile.
The reason for this is that Chamomile tea has a similar properties to Non-Prescription Anti-inflammatory Drugs (NSAIDs) like ibuprofen. While its potency is less than that of its drug relatives drinking frequent amounts of chamomile could still potentially cause harm. We feel for this reason it is best to avoid any chamomile tea while pregnant!