These are pink or purplish lines which usually occur on the tummy or sometimes on the upper thighs or breasts. Some women get them, some don’t. It depends on your skin type. Some people’s skin is more elastic. You are more likely to get stretch marks if your weight gain is more than average. It’s very doubtful whether oils or creams help to prevent stretch marks. After your baby is born the marks should gradually pale and become less noticeable.