Pregnancy stretch marks
Stretch marks are narrow pink or purplish streak-like lines that can develop on the surface of the skin. They're also known as stria or striae. If you get them, they usually appear on your tummy, or sometimes on your upper thighs and breasts as your pregnancy progresses. The first sign you notice might be itchiness around an area where the skin is becoming thin and pink.
What causes stretch marks?
Stretch marks are very common in the general population and don't just affect pregnant women. They can happen whenever the skin is stretched – for example, when we're growing during puberty or when putting on or losing weight, but hormonal changes in pregnancy can affect your skin and make you more likely to get stretch marks.
Our skin is made up of three main layers – the epidermis (the outer layer), the dermis (the middle layer) and the subcutis (the inner layer). Stretch marks happen in the middle layer, when the skin is stretched quite a bit over a short time. This stretching can break the dermis in places, forming stretch marks.
Whether or not you get stretch marks depends on your skin type, as some people's skin is more elastic. After your baby is born, the marks should gradually fade and become less noticeable, but they won't go away completely.
Pregnancy weight gain
You are more likely to get stretch marks if your weight gain is more than average in pregnancy. Most women gain between 10kg and 12.5kg (22 and 28lb) in pregnancy, although weight gain varies a great deal from woman to woman. How much weight you gain depends on your weight before you were pregnant. It's important that you don't diet to lose weight when you're pregnant, but you should eat a healthy, balanced diet.
If you are worried about your weight, talk to your midwife or GP. They may give you advice if you weigh more than 100kg (about 15.5 stone) or less than 50kg (about eight stone).
Stretch marks are not harmful. They don't cause medical problems and there's usually no need to see your GP, because there isn't a specific treatment for them. Over time, your skin will shrink and the stretch marks will fade into white-coloured scars.
Preventing stretch marks
Some creams claim to remove stretch marks once they've appeared, but there is no reliable evidence that they work. There is also limited evidence about whether oils or creams help prevent stretch marks from appearing in the first place.
A review of two studies looking at two specific creams marketed as preventing stretch marks found that massaging the skin may help to prevent stretch marks in pregnancy.
The studies suggested that there was little or no benefit for women who developed stretch marks in a previous pregnancy, but that women who had developed stretch marks in puberty seemed more likely to benefit from massaging cream.
However, more research is needed into whether creams or massaging the skin can help to prevent stretch marks.
Read more about other common health problems in pregnancy.