Is Ulthera safe before pregnancy?

Ultherapy has not been studied on pregnant patients, so I would hold off if currently pregnant. It works by thickening the fibromuscular layer of the face and neck as well as the dermis (second layer of skin), which leads to the lifting and tightening. If one loses or gains weight, it doesn't really have an effect on what the treatment itself does. Perhaps your before and after photos may be skewed, but otherwise there is no reason to wait to do it.

There are no studies that have been done with long term followup of those who had ultherapy and then became pregnant in a year or so after comparing them with those that didn't become pregnant. So I can't quote statistically or factually but the way I consider these noninvasive collagen-stimulating and tightening procedures is that they improve your baseline so that the after result whether you get pregnant or not, is that you will probalby have gained new collagen and the skin more tight than before. Should you have Ultherapy, and become pregnant later, and if your face changes dramatically during the pregnancy in shape and skin stretching, the final result after all the post partum changes have disappeared, might be better than if you didn't have the treatment but that isn't to say that your skin might not be looser than before pregnancy. After six months, or more, Ultherapy is often repeated in patients who were or weren't recently pregnant (but not during the pregnancy) so this can be done for someone before they become pregnant and after they deliver to improve the facial and neck skin.Unlike surgical procedures such as tummy tucks, that are avoided before pregnancy because of the more invasive procedure and riks it carries, and one would not want to jeopardize the surgical improvement when the skin of the abdomen becomes so stretched in pregnancy, the facial skin doesn't stretch that much and there is no surgical wound from ultherapy that could be worsened by the stretching in pregnancy.The information provided in Dr. Shelton's
answer is for educational purposes only and is not intended
to constitute medical advice. The information provided should
not be relied upon as a substitute for consultations with a qualified
health professional who may be familiar with your individual medical
needs.

If you are planning on having another child, I would wait until you have had the baby and lost your weight to do any treatment.  Being at a stable weight and having your hormones back to normal would most likely help with maximizing your result.     

I recommend that you wait after you deliver your child. There are hormonal alterations during pregnancy which may affect skin laxity (may) and therefore getting it BEFORE pregnancy may reduce the outcome you seek. Once the hormonal milieu has normalized, approximately 6 weeks after delivery, Ultherapy outcomes should be optimized. Read the Ultherapy ebook provided on the link below. 

If you plan on being pregnant in the near future, it may be best to wait until after your pregnancy to undergo an Ultherapy treatment. Although Ultherapy is not a weight loss treatment, the results of Ultherapy are more ideal when patients are at a stable weight beforehand. Because your skin will naturally stretch during pregnancy, it may be beneficial to undergo the treatment after your child is born.