When the skin is constantly rubbed, it initially becomes rough and then starts to develop acne-like bumps with continuing irritation like sweating or more friction. If the skin continues to be irritated for a longer period of time, a more serious acne lesion develops that grows in size and redness. They appear as small, red tender bumps called papules. There may be a combination of whiteheads and blackheads that also appear around the area affected, the difference being that whiteheads are closed and clogged pores whereas blackheads are also clogged but open pores. The symptoms may vary also depending on a persons skin type; overly oily or dry skin can cause a number of symptoms that heighten the possibility for acne mechanica to develop. Cause
Repetitive rubbing of the skin, in instances such as backpack strings rubbing on your shoulders or helmet straps rubbing on your chin are actions that can irritate the skin and cause acne mechanica. Acne mechanica is a specific type of acne that is caused by friction, heat, and/or pressure on the skin. Especially occurs when the skin is not exposed to air. It is commonly found in athletes because sweaty, constantly rubbed skin by a tight uniform, for example, can result in a rash. What may look like a rash is actually acne mechanica. Another common area for acne mechanica to show up is on the sides of your face where you hold your cell phone, especially with the added bacteria it carries on it.
The risk of preterm birth is inversely proportional to cervical length:
Less than 25 mm; 18% risk of preterm birth
Less than 20 mm; 25% risk of preterm birth
Less than 15 mm; 50% risk of preterm birth

Treatment
Cervical weakness is not generally treated except when it appears to threaten a pregnancy. Cervical weakness can be treated using cervical cerclage, a surgical technique that reinforces the cervical muscle by placing sutures above the opening of the cervix to narrow the cervical canal.Cerclage procedures usually entail closing the cervix through the vagina with the aid of a speculum. Another approach involves performing the cerclage through an abdominal incision. Transabdominal cerclage of the cervix makes it possible to place the stitch exactly at the level that is needed. It can be carried out when the cervix is very short, effaced or totally distorted. Cerclages are usually performed between weeks 12 to 14 of the pregnancy. The sutures are removed between weeks 36 and 38 to avoid problems during labor. The complications described in the literature have been rare: hemorrhage from damage to the veins at the time of the procedure; and fetal death due to uterine vessels occlusion. No significant differences in pregnancy outcomes were found in a study evaluating pregnancy outcomes after cervical conization. This study suggests for women with cervical insufficiency due to prior cone biopsy, cerclage is not superior to no intervention. As cerclage can induce preterm contractions without preventing premature delivery, makes the recommendation that it be used sparingly in women with a history of conization.