Introduction: To evaluate the maternal blood serum melatonin, soluble urokinase-type plasminogen activator receptor, and orosomucoid 2 levels in pregnant women complicated by preterm premature rupture of membranes (PPROM) and to compare the results with healthy pregnancies. In addition, to determine whether maternal/umbilical cord blood concentrations of melatonin, soluble urokinase-type plasminogen activator receptor, and orosomucoid 2 are of value in the diagnosis of histological chorioamnionitis in patients with preterm premature rupture of membranes (PPROM).

Methods: This cohort study will be included 44 pregnant women with PPROM and 44 gestational age-matched healthy subjects in 24-32 weeks of pregnancy. The blood for analysis will be firstly obtained in maternal blood on the day of diagnosis at the study group. Healthy subjects who have a normal pregnancy and outcomes without any fetal-neonatal complications will be accepted into the control group. Forty-four gestational age-matched healthy pregnant women who will be delivered at term will be included in the study as the control group. In the control group, the pregnant women will be taken the maternal blood at the admission day. The women in both groups will be observed until the delivery and perinatal data will be noted. Then, the blood for analysis will be secondly obtained in maternal blood during termination of the pregnancy (or spontaneous labor) at the study group. Lastly, the blood for analysis will be also obtained in umbilical cord blood at the study group. These three markers levels will be measured using a commercially available enzyme-linked immunosorbent assay (ELISA) kit. The placenta will be sent to histological examination in the study group. These three markers levels in women with PPROM will be compared to those of volunteer healthy pregnant women. In the study group, these three markers levels at maternal serum and cord serum will be evaluated for histological chorioamnionitis and maternal/neonatal outcomes.

This observational case-control study will be conducted at the Department of Obstetrics and Gynecology, Cengiz Gokcek Public Hospital, Gaziantep, Turkey, between October 2020 and October 2021. The protocol was approved by the Ethics Committee for Clinical Research of Gaziantep University (reference no: 2020/276). The study strictly will be adhered to the principles of the Declaration of Helsinki. All subjects will be included in the study gave oral and written informed consent. Membrane rupture before labor and before 37 weeks of gestation is referred to as preterm premature rupture of membranes (PPROM). Every woman in the study population will be undergone obstetric ultrasound examination and fetal-maternal assessment will be carried out. The blood for analysis will be firstly obtained in maternal blood on the day of diagnosis at the study group. Healthy subjects who had a normal pregnancy and outcomes without any fetal-neonatal complications will be accepted into the control group. Forty-four gestational age-matched healthy pregnant women who will be delivered at term will be included in the study as the control group. In the control group, the pregnant women will be taken the maternal blood at the admission day. The women in both groups will be observed until the delivery and perinatal data will be noted. All The participants with PPROM will be also hospitalized. Then, the protocols for pregnant women with PPROM in our hospital are as follows: All patients with PPROM are hospitalized and expectant protocol is applied. After hospitalization until the delivery of baby, all pregnant women with PPROM receive prophylactic antibiotics for 1 week and betamethasone injection. The non-stress test and fetal movement determined by the mother are used for the detection of fetal well-being. The signs for clinical chorioamnionitis such as uterine tenderness, fever, purulent discharges from the cervical canal and inflammatory markers like white blood cell count (WBC) and C-reactive protein (CRP) levels are monitored carefully during the hospitalization. After a latency period, PPROM pregnancy will gone to spontaneous delivery or will be applied termination procedure. In the study group, the placenta will be stained with hematoxylin-eosin and will be examined under a light microscope for histological signs of neutrophil infiltration and chorioamnionitis. Then, this study will be determined maternal serum melatonin, soluble urokinase-type plasminogen activator receptor, and orosomucoid 2 levels in women with PPROM(n=44) compared to those of volunteer healthy pregnant women (n=44). Then, these three markers levels at maternal serum and cord serum will be evaluated for histological chorioamnionitis and maternal/neonatal outcomes in the study group.

Inclusion Criteria:

• Pregnant women complicated with PPROM
• Healthy pregnant women who will be delivered at term
• Singleton pregnancy

Exclusion Criteria:

1. pregnant women with any systemic condition (such as chronic hypertension, renal disease and )
2. women who have dyed their hair in the last 9 months
3. history of using any medication
4. presence of gestational hypertension or gestational diabetes
5. drug user
6. patients who had fetal congenital abnormalities or genetic syndromes
7. multiple-gestation pregnancies
8. intrauterine fetal death
9. women who had any other infection or fever
10. fetal distress at admission
11. cord prolapse
12. active labor
13. antenatal bleeding
14. cervical or uterine anomaly

PPROM Preterm premature rupture of membranes (PPROM) is defined as the prelabor rupture of membranes before 37 weeks' gestation. Preterm PROM complicates about 1% of deliveries overall.

The investigators consecutively will be recruited 44 subjects with PPROM, and 44 healthy pregnancies will be selected for the control group.