I could find no reference in any medical literature that proves that this product is harmful to the developing foetus. However, I don't believe such products have been available long enough for us to be aware of all the side effects. Dosage is largely related to the amount applied and the presence of any open areas which may enhance absorption. (In general, if a product has an odour similar to paint thinner or oil-based paints, it is best to avoid exposure at all times during pregnancy.)

The active ingredient in self-tanning products is DHA or dihydroxyacetone. It is an organic chemical and is absorbed through the skin. Undoubtedly, it is delivered through the placenta to the baby, albeit in small amounts.

As this product provides no real benefit and sunscreen would have to be applied anyway (self-tanning products provide no protection from UV radiation), I advise avoiding it. Avoidance is the wisest course of action as we don't know its potential effect on the various phases of foetal development.