The Paulina collection has been specifically designed to fit your growing shape right through 9 months - and even after. For the most flattering silhouette, the garments sizing is based on your pre-pregnancy size . Therefore we would recommend that if you were a size US 6 before, you would buy a Paulina size S now. However, if you feel you have gained more than the average pregnancy weight gain, we recommend that you select 1 size up.