The following signs and symptoms confirms the occurrence of preterm labor:

• Spotting or early bleeding due to the early effacement of the cervix.
• Progressive and frequent uterine contractions. usually 5 or more contractions per hour.
• Low back pain secondary to the impinging head of the baby in the birth canal.
• Fluid leak or gush primarily due to the premature rupture of membranes.
• Bloody mucous discharge suggests that the cervix is starting to open.

• Hypoxemia

  Recognition of the early signs of pulmonary edema enable swift clinical diagnosis and steps to be taken to prevent disasterous condition due to progressive hypoxemia. [ncbi.nlm.nih.gov]

• Wet Rales

  Physical examination disclosed wet rales over both lungs, sinus tachycardia and tachypnea. [ncbi.nlm.nih.gov]

• Abdominal Pain

  METHODS: Prospectively collected data of pregnant women presenting with symptoms of preterm labor (abdominal pain or tightening) at 24-34 weeks' gestation were retrieved from the research databases of the EQUIPP and PETRA studies for subanalysis. [ncbi.nlm.nih.gov]

  Wellbeing of Women ELS Jane Currie (A David primary supervisor) “Do women presenting with abdominal pain and negative urine dipstick tests in pregnancy have subclinical urinary tract infection?” [ucl.ac.uk]

  These symptoms include an increase in the amount of vaginal discharge, vaginal bleeding/spotting, a change in the type of discharge (eg. more watery or mucous-like), abdominal pain /cramping similar to period pains, and more than four contractions in [myvmc.com]

  These symptoms include an increase in the amount of vaginal discharge, vaginal bleeding/spotting, a change in the type of discharge (eg. more watery or mucous-like), abdominal pain/cramping similar to period pains, and more than four contractions in one [healthengine.com.au]

• Epigastric Pain

  Hypertension and epigastric pain could not be controlled after the operation. [ncbi.nlm.nih.gov]

• First Trimester Bleeding

  The following etiologic factors may lead to preterm labor: Multiple pregnancy Chorioamnionitis Severe congenital defects of the fetus Hypertension Premature rupture of membranes Polyhydramnios First trimester bleeding Cigarette smoking Illegal drug use [symptoma.com]

  trimester bleeding The mother's health problems or lifestyle choices that can lead to preterm labor include: Cigarette smoking Illegal drug use, often cocaine and amphetamines Physical or severe psychological stress Poor weight gain during pregnancy [medlineplus.gov]

• Back Pain

  Lower backache If you’re nearing the home stretch of your pregnancy, back pain may be all too familiar. [monbaby.com]

  Symptoms of preterm labor include contractions, cramps, back pain, or leaking of fluid from the vagina. Preterm labor may result in preterm birth. Babies born too early are at risk for many serious health problems. [stlouischildrens.org]

  The signs of premature labor include regular contractions that increase in intensity, back pain, pressure in your vagina, vaginal discharge or bleeding, and decreased fetal movement. [livestrong.com]

  If you have any symptoms of preterm labor, including contractions, cramps, back pain, or leaking of fluid from your vagina, contact your healthcare provider right away. [urmc.rochester.edu]

• Arthritis

  Corticosteroids: Hormones given to help fetal lungs mature, for arthritis, or for other medical conditions. Fetal Fibronectin: A protein that helps the amniotic sac stay connected to the inside of the uterus. [acog.org]

  Corticosteroids: Drugs given for arthritis or other medical conditions. These drugs also are given to help fetal lungs mature before birth. Fetal Fibronectin: A protein that is produced by fetal cells. [m.acog.org]

• Thigh Pain

  The critical signs include contractions greater than 4 per hour, rhythmic back or thigh pain, increasing pelvic pressure, unusual discharge, vaginal spotting/bleeding, or rupture of membranes, tenesmus, and urgency. [www1.cgmh.org.tw]

  The critical signs of recurrent preterm labor include contractions greater than 4 per hour, rhythmic back or thigh pain, increasing pelvic pressure, unusual discharge, vaginal spotting/bleeding, or rupture of membranes. [emedicine.medscape.com]

• Vaginal Discharge

  If you have any of these signs or symptoms before your 37th week of pregnancy, you may be experiencing preterm labor: Change in your vaginal discharge (watery, mucus or bloody) or more vaginal discharge than usual Pressure in your pelvis or lower belly [marchofdimes.org]

  The results of vaginal discharge tests and maternal serum C-reactive protein (CRP) level at admission, placental biopsy, and perinatal outcomes were searched. The prevalence of abnormal vaginal flora was calculated. [ncbi.nlm.nih.gov]

• Regular Uterine Contractions

  This communication describes a case of a pregnant woman who had an allergic reaction and regular uterine contractions after the ingestion of lobster meat, to which she was known to be allergic. [ncbi.nlm.nih.gov]

  Definition Preterm labor : Regular uterine contractions with cervical effacement, dilation, or both before 37 weeks gestation. [amboss.com]

  Signs & Symptoms of Preterm Labor The most common signs that you may give birth to a preemie include regular uterine contractions. Some women describe these symptoms as severe menstrual-type cramps in the lower part of the abdomen (tummy area). [healthcare.utah.edu]

  This study aimed to evaluate the effectiveness of nifedipine versus a placebo for inhibiting uterine contraction in threatened preterm labor. [dovepress.com]

  The effective dose was maintained for at least six hours after the cessation of regular uterine contractions; the dose was then progressively decreased until the infusion was ended. [nejm.org]

• Pelvic Pain

  If you are entering labor, you may notice symptoms such as a heavy feeling in the pelvis, cramping, spotting or bleeding, backache, and intermittent pelvic pain that lasts 30 to 90 seconds. [nyulangone.org]

  Vaginal bleeding Vaginal discharge that is unusual Severe, persistent, frequent headaches Pain or burning upon urination, or decrease in urination Persistent nausea or vomiting Leakage of fluid from the vagina Sharp pelvic pain or severe cramping Frequent [sidelines.org]

  Back pain: A constant low, dull back pain may be a sign of labor. Increased pelvic pressure: If you feel a significant increase in pressure in your pelvic area, call your doctor. [whattoexpect.com]

• Uterine Tenderness

  Clinical findings showed uterine tenderness, fever, leukocytosis and elevated C-reactive protein. H. cinaedi was isolated from amniotic fluid obtained by transabdominal amniocentesis. [ncbi.nlm.nih.gov]

  Preterm labor can be precipitated by chorioamnionitis which should be suspected in women with fever and uterine tenderness. [clinicaladvisor.com]

• Vulvar Edema

  With no further treatment, the vulvar edema gradually resolved during the next week. [ncbi.nlm.nih.gov]

The diagnosis of preterm labor precludes with the accurate determination of fetal gestational age that falls beyond 20 weeks and lower than 37 weeks, with concurrent regular contractions and vaginal spotting.

The following tests and procedures may be utilized to help in the diagnosis of preterm labor:

• Pelvic Examination will give the obstetrician an idea of how the baby may present during delivery, estimate the firmness of the uterus, and determine whether the cervix has started to open.
• Ultrasound: A pelvic sonogram can determine the accurate age of the fetus, its relative presentation, amniotic fluid volume, length of cervix and baby’s size.
• Uterine monitor will determine the actual spacing of the uterine contractions.
• Fetal monitoring is used to monitor the fetal heart rate during the course of the labor to determine the child’s well-being.
• Laboratory test: Vaginal swabs may be taken to determine the presence of fibronectin and the possible presence of infectious organisms. 
• Maturity amniocentesis: This laboratory study involves the extraction of amniotic fluid when the age of gestation is beyond 32 weeks to determine the fetal lung age and determine the presence of amniotic fluid infections [6].

• Capnocytophaga

  A case is reported of a woman in preterm labor with intact membranes from whose amniotic fluid, placenta, and infant's gastric aspirate an unusual organism, Capnocytophaga, was identified. The findings are discussed. [ncbi.nlm.nih.gov]

The following treatment modalities are done to prevent the progression of preterm labor to preterm delivery:

• Cervical cerclage: This surgical procedure is done to reinforce the cervix and prevent preterm birth in an incompetent cervix condition.
• Corticosteroids: Patients in preterm labor between 24 to 34 weeks of gestation may benefit from betamethasone or dexamethasone injections to hasten the lung maturity of the neonate before preterm birth [7].
• Tocolytics: This group of medications may be given to patients in preterm labor to halt the uterine contractions and its progression. Tocolytics are not routinely given to preterm labor cases beyond 34 weeks, deliveries are postponed till the 37th weeks to significantly lower neonatal mortality and morbidity [8]. The use of magnesium sulfate as a tocolytic agent has been found to decrease the incidence of cerebral palsy and low birth weight infants [9].

Patients with less frequent contraction without bleeding may still be able to tocolyze the preterm labor till term pregnancy. However, patients presenting with rapid contractions with eminent bleeding may have an increased chance to progress to preterm delivery.

The relative prognosis of neonates born through preterm labor varies directly with age of gestation, and varies inversely with the number of congenital defects seen. This prognostic relationship is also true with maternal and neonatal morbidity and mortality ratings respectively.

Complications

The following medical conditions are common complication of preterm labor:

• Preterm delivery
• Premature rupture of membranes
• Premature neonate
• Neonatal sepsis
• Recurrent preterm labor

The progression to preterm labor is influenced by the maternal health, lifestyle and inherent anatomical defects. The following etiologic factors may lead to preterm labor:

• Multiple pregnancy
• Chorioamnionitis
• Severe congenital defects of the fetus
• Hypertension
• Premature rupture of membranes
• Polyhydramnios
• First trimester bleeding
• Cigarette smoking
• Illegal drug use
• Severe psychological and physical Stress
• Obesity
• Previous preeclampsia [1]
• Poor weight gain during pregnancy
• Short cervical length [2]
• Cervical incompetence
• Abnormal uterine shape
• Abruptio placenta and placenta previa

Preterm labor initiates more than half of preterm deliveries and is considered as the leading cause of neonatal mortality in the United States today [3]. Preterm births accounts for the 70% of neonatal morbidity and mortality [4].

The relative risk of preterm births due to preterm labor may be averted by the prompt and early identification of risk factors among mothers with less than 37 weeks of gestation. The active reduction of extreme prematurity (less than 32 weeks) will significantly reduce the mortality, morbidity and the inherent expenses during the delivery [5].

The pathophysiology of preterm labor lies on the nature of the inciting factor that induces labor. Preterm infection like chorioamnionitis or maternal septicemia may trigger uterine labor prematurely. The relative mass of the conceptus pressing against the thinning cervix may be influenced by twining or multiple pregnancies. Consequently, the cervical competence and amniotic fluid volume is also an important contributory factor in the progression of the preterm labor.

Extrinsic factors that trigger neurotransmitter release in the maternal system like cigarette smoking, psychological stress and physical stress may induce premature contractions of the uterus.

Mothers who begin to feel uterine contractions should take a short walk, change position or rest for a few minutes to quell the preterm contractions at home. Frequent false contractions in the preterm period is a risk factor for preterm labor in the late preterm stages (34-36 weeks) [10].

Persistent contraction despite these remedies must be brought in to the nearest obstetric care facility for proper assessment and monitoring. Adequate rest and fluid intake during intermittent uterine contractions may prove to be beneficial in some cases of preterm labor.

Preterm labor is a clinical condition defined as the premature opening of the cervix due to frequent uterine contractions before 37 weeks of gestation. When such event is unabated, this may result to the delivery of a premature baby that may require special care upon birth and may be at risk to long term complications. Mothers who underwent preterm labor may be at risk to another preterm labor on her next pregnancy.

Definition

Preterm labor is defined as the frequent uterine contraction that lead to the opening of the cervix before term pregnancy.

Cause

Multiple pregnancy, infections, stress, cervical incompetence, deficient amniotic fluid, placental abruption, and placenta previa may lead to preterm labor.

Symptoms

Frequent uterine contractions with shorter intervals, bleeding per vagina, cervical effacement and early rupture of membranes are common symptoms.

Diagnosis

Pelvic examination, ultrasound, fetal and uterine monitoring and amniocentesis are used to diagnose preterm labor.

Treatment and follow-up

Cervical cerclage, corticosteroids to enhance fetal lung maturity, and tocolytics to control preterm contractions are the treatment options.

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2. Durnwald CP, Walker H, Lundy JC, Iams JD. Rates of recurrent preterm birth by obstetrical history and cervical length. Am J Obstet Gynecol. Sep 2005; 193(3 Pt 2):1170-4.
3. American College of Obstetricians and Gynecologists. ACOG Practice Bulletin. Assessment of risk factors for preterm birth. Clinical management guidelines for obstetrician-gynecologists. Number 31, October 2001. (Replaces Technical Bulletin number 206, June 1995; Committee Opinion number 172, May 1996; Committee Opinion number 187, September 1997; Committee Opinion number 198, February 1998; and Committee Opinion number 251, January 2001). Obstet Gynecol. Oct 2001; 98(4):709-16.
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8. Cheng Y, Kaimal A, Bruckner T, Hallaron D, Caughey A. Perinatal morbidity associated with late preterm deliveries compared with deliveries between 37 and 40 weeks of gestation. BJOG. Nov 2011; 118(12):1446-1454.
9. Conde-Agudelo A, Romero R. Antenatal magnesium sulfate for the prevention of cerebral palsy in preterm infants less than 34 weeks' gestation: a systematic review and metaanalysis. Am J Obstet Gynecol. Jun 2009; 200(6):595-609.
10. Chao TT, Bloom SL, Mitchell JS, McIntire DD, Leveno KJ. The diagnosis and natural history of false preterm labor. Obstet Gynecol. Dec 2011; 118(6):1301-8.