Research question:

Population of study: women diagnosed as term pregnancy in labor (control) and the other group diagnosed as preterm labor (cases).

Intervention: measuring uterine natural killer cells . Outcome: uterine natural killer cells has a role in initiation of preterm labor.

Research hypothesis:

• Are uterine Natural Killer cells involved in the initiation of preterm labor ?

Medical Application:

• Possibility of prediction of preterm labor by assessment of Natural killer cells as well as preventing preterm labor by suppressing their activity .

Type of the Study:

This is a case control study .

Study Settings:

This clinical trial will be conducted at Ain Shams University Maternity Hospital and the laboratory work will be done at Ain Shams University histopathology Laboratory , in the period between August 2012 to August 2014 .

Study Population:

The patients will be recruited from women attending casualty at Ain Shams University Maternity Hospital.

The included patients will be

Divided into two groups:

• Group 1: Patients who has threatened preterm labor and will receive tocolysis and these patients will either not respond to tocolysis and delivered preterm or will respond to tocolysis and will deliver at term .
• Group 2: Patient delivered vaginally at term with no history of having tocolysis for preterm labor at the current pregnancy .

Intervention:

After taking informed written consent, the recruited patients will be subjected to the following:

- History taking, with particular emphasis on: Past medical history (no diabetes mellitus, no hypertension, etc..) Past obstetric history (history of preterm labor). Menstrual history(to be sure of her LMP( last menstrual period) and this date is reliable).

• Having earlier ultrasound to document gestational age.
• History of labor pains which is becoming regular and frequent.
• No suggestive history of preterm prelabor rupture of membranes
• General examination with particular emphasis on blood pressure, weight and height.
• Abdominal examination with particular emphasis on uterine activity.
• Obstetric ultrasound (transabdominal) to document viability of pregnancy and to ensure the gestational age.
• Included patients will receive tocolysis (according to Ain Shams University Maternity hospital protocol which is recommending usage of calcium channel blocker (Nifedipine) Initially 10mg orally every 15 minutes, up to 4 doses of Nifedipine to stop contractions. After this slow release nifedipine. It has been found that an 8 hourly dosage of 40mg - 20mg - 40mg calcium channel blocker is suitable for most women. This is in addition to use of steroids to enhance lung maturity (dexamethasone, 6 mg intramuscular /12 hrs for 48 hrs)
• Patients will be traced by fetal monitor and uterine tocodynamometer (Oxford Sonicaid Team ®)to monitor uterine contractions and if the treatment was successful or not.
• After delivery a placental sample will be taken either the patient delivered preterm or at term (term patients will be either control term group or patients with successful treatment of preterm labor). The placental sample taken should have part of the decidua and then the sample will be fixed in 10% neutral-buffered formalin for 24-48 h, routinely processed, embedded in paraffin wax, sectioned at 3 μm thickness, and mounted on 3-aminopropyl-triethoxysilane -coated slides. Serial sections will be immunostained for CD 16 and CD56 . immunohistochemistry study will be done at Ain Shams Maternity Hospital Histopathology department.

Inclusion Criteria:

1. Maternal age: 18-35 years old (to decrease the incidence of preterm labor related to age factor).
2. Women who present with viable pregnancy (between 28 and 37 weeks' gestation), and having a threatened preterm labor (which is defined as ≥ 2 uterine contractions at 28-37 weeks' gestation, The onset of labor may be determined by documented uterine contractions (at least one every 10 minutes) and ruptured fetal membranes or documented cervical change with an estimated length of less than 1cm or cervical dilation of more than 2 cm. Threatened preterm labor may be diagnosed when there are documented uterine contractions but no evidence of cervical change.

Exclusion Criteria:

1. Multiple pregnancy.
2. Documented uterine anomalies.
3. Oligohydramnios and polyhydramnios .
4. Medical disorders as Diabetes mellitus and hypertension.
5. Preterm premature rupture of membranes.
6. Conditions that may have an influence on immune reaction e.g. history of chorioamnionitis.
7. Smoking as a risk factor for preterm labor.
8. Patients having Autoimmune disorder as it may affect Uterine NK( natural killer ) cells level .

The patients will be recruited from women attending casualty at Ain Shams University Maternity Hospital.

2 years