Lip fillers are not recommended during pregnancy. There isn’t enough evidence to determine the safety of fillers during this time as no studies have been performed.
Additionally, there’s normal swelling that comes with pregnancy, which may impact the appearance of the lips. If filler is performed during this temporary state, it may not necessarily be the same amount of placement as if there were no swelling.
There can also be a greater risk of infection, post-procedure swelling, and bruising during pregnancy. That said, for someone who received filler prior to becoming or knowing they are pregnant, it’s unlikely to cause any issue, as many fillers are made up of hyaluronic acid, a sugar molecule found naturally in our bodies.