Health and Symptoms / 27 April, 2023 / Dr Clare Thompson
Treating stretch marks is a common issue that comes up time and again in my clinic. The unwelcome appearance of these pesky red marks cropping up over the body serves as a stark reminder of a pregnancy or else a significant amount of weight gained at some point in time. Although the end result of having a healthy baby is undoubtedly worth a few blemishes, it is certainly nice to know that there are ways that they can be minimised and treated.
I’m sure you will have seen the many adverts of a glowing, expectant mother clutching her pregnant belly and proclaiming the wonders of various creams and oils in keeping her skin stretch-mark free, but studies in fact suggest that there is little evidence behind these claims and that creams may only be targeting the top layer of skin whilst treating the itching and dryness associated.
Although stretch marks are mostly genetic there are absolutely things that you can do to prepare your skin for pregnancy and reduce the chances of long term scar formation associated.
Stretch Marks (Striae Distensae) are a type of ‘scarring’ that happens when the skin is stretched beyond the limits of its elasticity due to rapid expansion or contraction of the skin. They often appear as red or purplish raised marks and slowly fade and flatten to a silvery-white pattern over time.
The dermis is the middle layer of the skin which contains nerve endings, sweat glands, sebaceous (oil) glands and blood vessels. When connective tissue is abruptly stretched it causes tearing which allows deeper skin layers to show through, forming stretch marks.
As the body grows, the strong connective fibres in the dermis slowly stretch. However, with rapid growth the fibres over stretch and break. Stretch marks appear purplish initially because of the blood vessels showing through tears in the dermis. Stretch marks eventually fade over time to a silver-white pattern as the blood vessels contract and the pale fat underneath the skin becomes visible instead.
Before stretch marks begin to emerge the skin can appear thin and pink and may be irritated or itchy.
Cortisol is the stress hormone which is produced by the adrenal glands and is converted to cortisone which weakens the elastic fibres in the skin. Stretch marks are more likely to develop when there are high levels of circulating cortisol or where topical cortisone (steroid cream) is used for prolonged periods of time.
Fibroblasts are the ‘construction workers’ in the dermis of the skin which are responsible for collagen production. Collagen is a fibrous protein found in the skin and other connective tissues of the body. Collagen is important to the way the skin looks and feels because it is the main structural component providing firmness and shape.
The skin structure of stretch marked skin shows slower growth of fibroblasts and less production of elastin, collagen and fibronectin. The altered appearance of stretch marked skin reflects the structural changes in the dermis. Studies also show that people with stretch marks have a different phenotype (genetic makeup) in the fibroblasts compared with healthy skin. This is consistent with the hypothesis that there is a genetic tendency for people to develop stretch marks.
Regardless of the cause, all stretch marks display the same changes in the dermis which are similar to those seen at a cellular level in scar formation.
Almost 50% of pregnant women will develop some stretch marks to varying degrees, usually appearing after 25 weeks gestation when there is sudden weight gain and stretching of the dermis. A lot of this will have a genetic undertone but the hormonal changes in the body and the stretching of the skin to the abdomen, hips and breasts also plays a role. High circulating levels of hormones produced in pregnancy act to soften the pelvic ligaments and increase their flexibility but also soften skin fibres giving an increased risk of stretch marks.
Higher maternal age at delivery is associated with a LOWER risk of stretch marking, possibly due to different circulating levels of oestrogen and its effects on collagen production.
People with a higher BMI will be at greater risk of stretch marks due to the greater stretch applied to the skin in obesity.
Teenagers and younger women are more prone to stretch marking than any other group and this is postulated to be due to the changes in skin collagen and connective tissue that are age-related and affect the likelihood of tearing. Areas of skin that undergo greater mechanical stretching may respond differently to hormonal signals from oestrogens and natural steroids. The skin cells in younger patients appear to express greater hormonal receptor activity and studies have suggested that there may be up to twice as many oestrogen receptors in the skin of patients who are prone to stretch marks. In young males stretch marks tend to arise at the shoulders and back, whereas young females often develop marks to the thigh, hip and breast areas.
‘23 and Me’ , the leading personal genetics company, has conducted the first study of stretch marks and researchers have identified 4 possible genes responsible for predisposing to susceptibility to stretch marks. Joyce Tung PhD and director of research at ‘23 and Me’ reports that they are beginning to uncover new genetic associations through a genome-wide association analysis across 33, 930 unrelated participants of European descent. Loose skin is thought to be caused by a deletion or mutation in the elastin proteins found in the skin cells. Variations of elastin and collagen gene expression in the dermis of the skin contributes to the reorganisation and overall loss of elastic fibres resulting in stretch mark patterns.
Prolonged or inappropriate use of topical steroids can cause stretch marks by inhibiting fibroblast activity and decreasing collagen production, thus ‘thinning the skin’. This is often why your Doctor will only suggest using steroid creams for short periods of time (eg/ in eczema).
Cushing’s disease is a condition in which there is an overproduction of the stress hormone cortisol. This leads to rapid weight gain, especially in the trunk, in addition to the skin becoming more fragile and thin with propensity for easy bruising, scarring and infection.
Ehlers-Danlos Syndrome is a rare inherited condition that disrupts the structure of proteins in the skin which can also cause stretch marks.
Marfans Syndrome is another genetic condition that causes weakness and decreased elasticity in the body tissues.
Diagnosis is clinical and fairly obvious from the appearance of the skin. Ultrasound techniques have also been used to detect and measure stretch mark type and maturation.
Creams, oils and topical preparations have all been proposed as potential therapies for stretch marks although there is little evidence to the support their efficacy.
There is no high quality evidence to support the use of topical preparations in the prevention of stretch marks during pregnancy. However, creams and oils do help with the dryness and itch symptoms associated.
Studies on the use of cocoa butter, olive oil and bitter almond oil have shown no absolute benefit when compared to control groups.
Products containing retinoic acid are UNSAFE for use in pregnancy and breastfeeding but studies suggest that topical application of retin-A can improve the clinical appearance of stretch marks. The process responsible for this clinical improvement is unknown.
Application of silicone gels can help promote collagen production and reduce pigmentation of stretch marks when compared to placebo groups.
This is a popular technique that Dermatologists use to polish the top layer of the skin by blowing fine crystals across it and removing the superficial layer to stimulate new growth of skin. The procedure can be of benefit in early stretch marks.
Laser therapy works to stimulate new collagen and elastin fibre synthesis in the dermis.
Pulsed dye laser techniques have been shown to be effective at improving the appearance of early stretch marks. Fractional laser treatment has better evidence for treating older stretch marks.
PRP (platelet rich plasma) is a blood plasma that has been enriched with platelets and contains several different growth factors to stimulate healing of soft tissues. Many Dermatologists are now using this technique with good results.
There is also some evidence that Centella Asiatica (gotu kola), which is a small herbaceous perennial plant, can prevent stretch marks by promoting collagen synthesis and fibroblast proliferation and increase intracellular fibronectin content. This helps to improve the tensile strength of newly formed skin while inhibiting inflammation that leads to the developing of hypertrophic scars and keloids.
By Dr Clare Thompson, The Courtfield Private Practice, South Kensington.
The Courtfield Private Practice’s head partner is Dr Tim Ladbrooke, the GP in Tatler’s Best Doctor Guide. The practice is expanding and and concentrating its focus on mothers and children.