1) Infection
Systemic and genital tract infections are significantly associated with preterm birth. In women in spontaneous preterm
labor and intact membranes, lower genital tract flora are commonly found in the amniotic fluid, placenta, and membranes.
The flora include Ureaplasma urealyticum,Mycoplasma hominis, Fusobacterium species, Gardnereilavaginalis,
🔹
peptostreptococci, and bacteroides species. Trichomonas vaginalis has also been linked to preterm birth.
Chorioamnionitis:
is the cause of 20% to 30% of all cases of preterm labor.
The -clinical diagnosis of Chorioamnionitis requires:
* Fever (≥ 100° For 37.8° C) and at least two of the following conditions:
1.Maternal tachycardia.
2.Fetal tachycardia.
3.Uterine tenderness.
4.Foul odor of amniotic fluid
5.Maternal leukocytosis
Women with a signs and symptoms of overt acute Chorioamnionitis have reached a final stage in the progression of their
uterine infection.
🔹
In these cases, labor is a mechanism of fetal and maternal protection and should not be interrupted.
Subclinical Chorioamnionitis is an infection of the product of conception without clinical signs and symptoms of
🔹 A preterm birth is defined as one that occurs before the completion of 37 menstrual weeks of
gestation (≤36 6/7 weeks), regardless of birth weight, (259 days from the first day of the mother's last
disease.
The diagnosis by amnniotic fluid (AF) analysis. There are several AF tests that can be used for this purpose, among them
are: The gram stain and WBC count,Bacterial culture, Limulus amebocyte assay, Acridine orange stain to allow
🔹
normal menstrual period, or 245 days after conception).
Low birth weight (LBW) is defined by birthweight below 2500 g regardless of
gestationalage.Gestational age and birth weight are related by the terms small for gestational age
ETIOLOGY
visualization of mycoplasma in AF, determination of the concentration of glucose, LDH, and interleukin (IL)-6.CRP
concentration in the maternal plasma can be used.
(birthweight less than the 10"h percentile for gestational age), appropriate for gestational age(birth
weight between the 10th and 90th percentiles), and large for gestational age (birthweight above the 9oth
DEFINITIONS 🔹
In addition to Histological examination of the placenta.
Infections outside the genital tract have also been related to preterm birth,most commonly to urinary tract and intra-
abdominal infections, for example, pyelonephritis and appendicitis.
🔹
percentile).
An LBW infant is one whose birth weight- is less than 2,500 g; a very low birth
weight(VLBW)infant is one whose birth weight is less than 1,500 g, and an extremely low birthweight
Recent literature links maternal periodontal infection and inflammation to preterm birth.
(ELBW)infant is one whose birth weight is less than 1,000 g. 2) Placental abnormalities:
Several evidences indicate that abnormal placentation may be one of the etiologic agentscausing preterm birth. It
includes:Anatomic abnormalities. Placenta previa. Severe abruptio placentae. Placental vascular insufficiency.
3) Anatomic abnormalities of the uterus:
The Diagnosis of preterm comprises the following three considerations: Congenital abnormalities of the uterus and cervix account for about 1% to 3% of cases ofpreterm labor. The most
1. Identification of the patient at risk for preterm labor. important of these conditions are the septate and bicornateuterus.Abnormal cervical development may cause reduced
2. Diagnosis of threatened or imminent preterm labor (Early warning symptoms). cervical sufficiency.
3. Diagnosis of established preterm labor. 4) Fetal pathology:
Neural tube defects and Inborn error of metabolism such as hyperalaninemia are some ofthe birth defects associated with
I. Identification of the patient at risk for preterm labor: preterm labor.
The Identification of the patient at risk for preterm labor has followed two differentapproaches. The first consist of determining the 5) Uterine overdistension:
woman's riskof preterm delivery on thebasis of socioeconomic and past medical and reproductive risk Factors. A second approachis Stretching of the uterine muscle because of multifetal pregnancy or an excessive amount ofamniotic fluid is another
the use of tests to determine the risk. The best predictor of preterm labor is a poor pastreproductive performance. relatively common cause of preterm labor.
🔹
II. Diagnosis of threatened or imminent preterm labor (Early warning symptoms):
The majority of patients who develop preterm labor have one or more of the followingsymptoms and signs:
-Menstrual-like cramps (constant or come and go just above the pubic bone).
6) Preterm labor of unknown origin:It is not possible to establish precisely the etiology of preterm labor in 20-30%
of the cases
-Low dull backache (constant or comes and goes).
DIAGNOSIS OF PRETERM
-Pressure (feels like the baby is pushing down, feels heavy)
-Abdominal cramping (wvith or without diarrhea).
- Increase or change in vaginal discharge (may be mucous, watery, light or bloody). The frequency of preterm birth increased up to 6-10%; Preterm births after 32 weeks account for
-Increase vaginal discharge which can be mucoid or blood tinged. Fluid leaking from thevagina suggest premature rupture of most of the increase.
membrane. The rise in preterm births, in some countries, has been attributed to increased use of assisted
-Uterine contractions that are 10 minutes apart or closer (may be painless). reproductive technologies (ART), improved pregnancy dating by ultrasound, and increased willingness
- If any of the warning symptoms of preterm labor, pelvic examination should bedone.Shortening of the cervix, obliteration of the INCIDENCE to choose delivery when medical or obstetric complications threaten the health of the mother or
fornices and dilatation of the external osare confirmatory signs. fetus after 32 to 34 weeks' gestation.·
III. Diagnosis of established preterm labor: Spontaneous :40-50%·
It requires abnormal uterine activity and changes in cervical effacement and dilation PROM :25-40%·
Obstetrically indicated:20-25%
I. Management of patients at high risk for preterm labor:
1. Education about preterm labor.
2. Aggressive treatment of cervical and vaginal infections.
🔹
1) Assessment of Risk Factors:
While the exact cause of preterm labor is often unknown, there is strong evidence thatintrauterine infection may play a role in
every early preterm labor.
3. Frequent antenatal surveillance, including serial ultrasound examinations. -Previous preterm delivery: risk 20- 40%: Of all the predictors of preterm birth,past obstetrichistory is the strongest predictor of
4. Changes of life style. recurrent preterm birth.
5. Oral administration of tocolytic drugs.
6. Progesterone administration.
7. Cervical cerclage. preterm labor -Cigarette smoking
-Reduced body mass index (BMI)- BMI less than 19.0
-Interpregnancy interval of less than one year
🔷
II. Management of threatened or imminent preterm labor (Early warning symptoms):
1. Antibiotics:
-Maternal age (teenage multiparae)
-Nulliparous or grandmultiparous
🔷
It is possible that antibiotics are effective only when treatment is initiated early in theinfectious process.
2. Prophylactic tocolysis:
-Ethnicity (black women)
-Socioeconomic deprivation
🔸
Stopping uterine contractions may prevent further cervical effacement and the loss of the mucous plug.
Different types of tocolytic drugs are used such as:
1)Beta adrenergic agents:
-Unemployment
-Low level of education
2) Microbiological Screening:
act by promoting the extrusion of calcium from the cells. The medications most frequently used are Ritodrine and Terbutaline. Screening and treating lower genital tract and sexually transmitted infection isrecommended prior to and in the first trimester of
According to the Federal Register, Ritodrine was voluntarily withdrawn from the United States market in 2003. Adverse reports describe a sudden maternal death and a newborn with myocardial necrosisafter the mother PREDICTION pregnancy(bacterial,vaginosis,Asymptomatic bacteriuria, Group B streptococcal colonization).
🔻
used the pump for 12 weeks.
Contraindications to the use of intravenous beta-adrenergic agents:
3) Cervical Length Scan:
Vaginal U/S allows a more objective approach to examination of the cervix.When measuredby transvaginal ultrasonography, cervical
length is inversely and continuously related to therisk of preterm birth in both singleton and multifetal pregnancies. A positive
1.Symptomatic cardiac disease. predictive valueof 70% and a sensitivity of 60-80% is observed with a transcervical ultrasound cervical lengthof less than 25 mm
2.Symptomatic cardiac rhythmor conduction disturbance. between 14 and 18 weeks gestation.
3.Hyperthyroidism. 4) Fibronectin Test:
4.Sickel cell disease. This glycoprotein is produced in 20 different molecular forms by various cell types,includinghepatocytes, fibroblasts, endothelial
5. Uncontrolled insulin-dependent diabetes. 6.Chorioamnionitis. cells, and fetal amnion. Present in high concentrationsin maternal blood and in amnionic fluid, it is thought to function in intercellular
7. Eclampsia or severe pre-eclampsia. adhesionduring implantation and in maintenance of placental adherence to uterine decidua.
8.Multifetal gestation. Fetalfibronectin (fFN) is rarely present in the vaginal secretions between 23 and 34 weeks. Anydisruption at the chorio-decidual
9.Severe obstetrical bleeding. interface (before membrane rupture) results in fFN releaseand possible detection in cervicovaginal secretions and was a possible
10.Severe anaemia. marker forimpending preterm labor.
11. Patients on monoamine oxidase inhibitor. Fetal fibronectin is measured using an enzyme-linkedimmunosorbent assay, and values exceeding 50 ng/mL are considered positive.
12. Asthmatic patients already taking beta-adrenergic agents. Sample contamination by amnionic fluid and maternal blood should be avoided.
2)Magnesium salts:
acts by displacing calcium from the myometrial cells. Oral Magnesiumsalts can be given as a prophylaxis in threatened preterm labor.
When there are evidence of imminent preterm labor intravenous Magnesium sulfate is initiated if there is a need to postpone delivery.
intravenous magnesium sulfate-a 4-g loading dose followed by acontinuous infusion of 2 g/hr-usually arrests labor. 1.Maternal:
Recently, the FDA (2013) warned against prolonged use of magnesium sulfate given to arrest preterm labor due to bone thinning and fractures in fetuses exposed for more than 5 to7 days. This was attributed to low Maternal mortality and morbidity as consequences of preterm labor are rare. The most common maternal effects are feeling of
calcium leveIs in the fetus. inadequacy at fulfilling a reproductive role andincrease risk for the development of postpartum endometritis.
🔹
3)Calcium channel blockers: 2.Fetal consequences of preterm labor:
Myometrial activity is directly related to cytoplasmic free calcium,and a reduction in its concentration inhibits contractions. I.Perinatal mortality:
Calcium-channel blockers act to inhibit, by various mechanisms, calcium entry through cell membrane channels. Although they were developed to treat hypertension, their ability to arrest preterm labor hasbeen Preterm delivery is the leading cause of perinatal mortality, responsible for about 75% ofearly neonatal deaths. Perinatal mortality
🔹
evaluated. Investigators have also concluded that calcium-channel blockers, especially nifedipine, are safer and more effective tocolytic agents than are β-agonists.
The combination of nifedipine with magnesium for tocolysis is potentialy dangerous. As nifedipine enhances the neuromuscular blocking effects of magnesium that can interfere with pulmonary and cardiac function
4)Prostaglandin Inhibitors:
🔹
increases markedly as gestational age and birthweight decline.
II.Perinatal morbidity:
Preterm infants are at risk for specific diseases related to the immaturity of various organsystems and the cause and circumstances of
Prostaglandins are intimately involved in contractions of normal labor. preterm birth. Common complications inpremature infants include respiratory distress syndrome (RDS), intraventricular
Antagonists act by inhibiting prostaglandin synthesis or by blocking their action ontarget organs. hemorrhage(IVH),bronchopulmonary dysplasia (BPD), patent ductus arteriosus (PDA), necrotizingenterocolitis (NEC), sepsis, apnea,
🔹
Indomethacin is administered orally or rectally. and retinopathy of prematurity. The frequency of majormorbidity rises as gestational age decreases, especially below 30 weeks.
A dose of 50 to 100 mg isfollowed at 8-hour intervals not to exceed a total -24 hour dose of 200 mg. Serum concentrations usually peak 1 to 2 hours after oral administration, whereas levels after rectal administration III.Long-Term Outcomes:
peak slightly earlier. MANAGEMENT OF PRETERM LABOR Major neonatal morbidities related to preterm birth that carry lifetime consequences includechronic lung disease, grades IlI and IV IVH
Most studies have limited indomethacin use to 24to 48hours because of concerns for oligohydramnios, which can develop with these doses. (associated with cerebral palsy), NEC, and vision and hearing impairment.
If amnionic fluid is monitored, oligohydramnios can be detected early, and it is reversible with drug discontinuation. CONSEQUENCES OF PRETERM LABOR Follow-up studies of infants born preterm and LBW infants reveal increased rates of cerebral palsy, neurosensory impairment,
reduced cognition and motor performance, academic difficulties, and attention deficit disorders.
5)Progesterone:
acts by its antagonistic effect on prostaglandin F2-alpha and its ability toblock the development of gap junction necessary for the propagation of muscular activity.
6)Atosiban: OUTCOMES FOR INFANTS BORN PRETERM
This nonapeptide oxytocin analogue is a competitive antagonist ofoxytocin-induced contractions. In randomized clinical trials, atosiban failed to improverelevant neonatal outcomes and was linked with significant Gestational age at birth is strongly correlated with adverse pregnancy outcomes that include
neonatal morbidity. stillbirth (fetal death after 20weeks' gestation), deaths of neonates (<28 days) and infants
7)Nitric Oxide Donors: (<12months), and long-term physical and intellectual morbidities.
These potent smooth-muscle relaxants affect the vasculature,gut,anduterus. Nitric Oxide Donors like nitroglycerine have been tested as tocolytics,administeredeither intravenously or in form of transdermal patches.
The current RCOG guidelines suggest atosiban and nifedipine as they appear to havecomparable effectiveness in delaying delivery, with fewer maternal side effects than alternatives such as ritodrine or indomethacin.
🔷
Although the use of nifedipine for preterm labour is unlicensed, it has the advantages of less frequent side effects, oral administration and a low purchase price.
3. Antenatal Corticosteroids Administration Current evidence supports the administration of a single course of antenatal corticosteroidsbetween 24 and 34'6 weeks of gestation to enhance fetal lung maturation.
It reduced the risk of neonatal death by 31%, respiratory distress syndrome by 44% and intraventricularhaemorrhage by 46%.
⭐ MAGNESIUM SULPHATE FOR NEUROPROTECTION:
Antenatal magnesium sulphate therapy given to women at risk of preterm birth substantiallyreduced the risk of neonatal cerebral palsy.
There was also a significant reduction in the rate of substantial gross motor dysfunction. It is recognized that the magnitude of the beneficial effect is likely to be higher at earlier gestations and limited at gestations by fatema okoff
above 32 weeks. For this reason and due to concerns over adverse neonatal outcomes reported in an earliertrial, its use above 32 weeks' gestation is not advocated.
The current recommendation is a 4g IV loading dose followed by a maintenance dose of 1 g per hour for 24 h unless precededby birth.
🔹
III. Management of patients with established preterm labor:
1. Identification of patients that needs to be delivered e.g.:
1. Maternal disease: like the presence of hyperthyroidism, chronic hypertension,pre-eclampsia, chronic renal disease.
2. Advanced labor: patients with 5 cm or more, 100% effaced and with membrane bulging.
3. lethal fetal congenital anomalies.
4. Fetal growth restriction.
5. Chromosomal abnormalities.
6. Chorioamnionitis.
🔹
7. Adequate fetal pulmonary maturity.
2.Treatment of patients who need to postpone their delivery:
1) The use of intravenous tocolysis: The main objective of treatment is to keep patientsundelivered for the shorttime necessary for glucocorticoid treatment.
2) Antibiotics.
3) Glucocorticoids.
4) Phenobarbital.
🔶
5) Vitamin K1.
Intrapartum management of preterm labor
1. Frequent or continuous FHR monitoring.
2. Prevention of neonatal GBS infection.
3. CS indicated in any abnormal delivery, or prolongation of the active phase of labor
4. Episiotom y is needed, unless the vulva is patuolous.
5. Prophylactic vitamin K administration to the mother.
6. Prophylactic phenobarbital administration to the mother.
7. The availability of experienced resuscitation and neonatology care.
8. Epidural analgesia are the best for pain relief
Systemic and genital tract infections are significantly associated with preterm birth. In women in spontaneous preterm
labor and intact membranes, lower genital tract flora are commonly found in the amniotic fluid, placenta, and membranes.
The flora include Ureaplasma urealyticum,Mycoplasma hominis, Fusobacterium species, Gardnereilavaginalis,
🔹
peptostreptococci, and bacteroides species. Trichomonas vaginalis has also been linked to preterm birth.
Chorioamnionitis:
is the cause of 20% to 30% of all cases of preterm labor.
The -clinical diagnosis of Chorioamnionitis requires:
* Fever (≥ 100° For 37.8° C) and at least two of the following conditions:
1.Maternal tachycardia.
2.Fetal tachycardia.
3.Uterine tenderness.
4.Foul odor of amniotic fluid
5.Maternal leukocytosis
Women with a signs and symptoms of overt acute Chorioamnionitis have reached a final stage in the progression of their
uterine infection.
🔹
In these cases, labor is a mechanism of fetal and maternal protection and should not be interrupted.
Subclinical Chorioamnionitis is an infection of the product of conception without clinical signs and symptoms of
🔹 A preterm birth is defined as one that occurs before the completion of 37 menstrual weeks of
gestation (≤36 6/7 weeks), regardless of birth weight, (259 days from the first day of the mother's last
disease.
The diagnosis by amnniotic fluid (AF) analysis. There are several AF tests that can be used for this purpose, among them
are: The gram stain and WBC count,Bacterial culture, Limulus amebocyte assay, Acridine orange stain to allow
🔹
normal menstrual period, or 245 days after conception).
Low birth weight (LBW) is defined by birthweight below 2500 g regardless of
gestationalage.Gestational age and birth weight are related by the terms small for gestational age
ETIOLOGY
visualization of mycoplasma in AF, determination of the concentration of glucose, LDH, and interleukin (IL)-6.CRP
concentration in the maternal plasma can be used.
(birthweight less than the 10"h percentile for gestational age), appropriate for gestational age(birth
weight between the 10th and 90th percentiles), and large for gestational age (birthweight above the 9oth
DEFINITIONS 🔹
In addition to Histological examination of the placenta.
Infections outside the genital tract have also been related to preterm birth,most commonly to urinary tract and intra-
abdominal infections, for example, pyelonephritis and appendicitis.
🔹
percentile).
An LBW infant is one whose birth weight- is less than 2,500 g; a very low birth
weight(VLBW)infant is one whose birth weight is less than 1,500 g, and an extremely low birthweight
Recent literature links maternal periodontal infection and inflammation to preterm birth.
(ELBW)infant is one whose birth weight is less than 1,000 g. 2) Placental abnormalities:
Several evidences indicate that abnormal placentation may be one of the etiologic agentscausing preterm birth. It
includes:Anatomic abnormalities. Placenta previa. Severe abruptio placentae. Placental vascular insufficiency.
3) Anatomic abnormalities of the uterus:
The Diagnosis of preterm comprises the following three considerations: Congenital abnormalities of the uterus and cervix account for about 1% to 3% of cases ofpreterm labor. The most
1. Identification of the patient at risk for preterm labor. important of these conditions are the septate and bicornateuterus.Abnormal cervical development may cause reduced
2. Diagnosis of threatened or imminent preterm labor (Early warning symptoms). cervical sufficiency.
3. Diagnosis of established preterm labor. 4) Fetal pathology:
Neural tube defects and Inborn error of metabolism such as hyperalaninemia are some ofthe birth defects associated with
I. Identification of the patient at risk for preterm labor: preterm labor.
The Identification of the patient at risk for preterm labor has followed two differentapproaches. The first consist of determining the 5) Uterine overdistension:
woman's riskof preterm delivery on thebasis of socioeconomic and past medical and reproductive risk Factors. A second approachis Stretching of the uterine muscle because of multifetal pregnancy or an excessive amount ofamniotic fluid is another
the use of tests to determine the risk. The best predictor of preterm labor is a poor pastreproductive performance. relatively common cause of preterm labor.
🔹
II. Diagnosis of threatened or imminent preterm labor (Early warning symptoms):
The majority of patients who develop preterm labor have one or more of the followingsymptoms and signs:
-Menstrual-like cramps (constant or come and go just above the pubic bone).
6) Preterm labor of unknown origin:It is not possible to establish precisely the etiology of preterm labor in 20-30%
of the cases
-Low dull backache (constant or comes and goes).
DIAGNOSIS OF PRETERM
-Pressure (feels like the baby is pushing down, feels heavy)
-Abdominal cramping (wvith or without diarrhea).
- Increase or change in vaginal discharge (may be mucous, watery, light or bloody). The frequency of preterm birth increased up to 6-10%; Preterm births after 32 weeks account for
-Increase vaginal discharge which can be mucoid or blood tinged. Fluid leaking from thevagina suggest premature rupture of most of the increase.
membrane. The rise in preterm births, in some countries, has been attributed to increased use of assisted
-Uterine contractions that are 10 minutes apart or closer (may be painless). reproductive technologies (ART), improved pregnancy dating by ultrasound, and increased willingness
- If any of the warning symptoms of preterm labor, pelvic examination should bedone.Shortening of the cervix, obliteration of the INCIDENCE to choose delivery when medical or obstetric complications threaten the health of the mother or
fornices and dilatation of the external osare confirmatory signs. fetus after 32 to 34 weeks' gestation.·
III. Diagnosis of established preterm labor: Spontaneous :40-50%·
It requires abnormal uterine activity and changes in cervical effacement and dilation PROM :25-40%·
Obstetrically indicated:20-25%
I. Management of patients at high risk for preterm labor:
1. Education about preterm labor.
2. Aggressive treatment of cervical and vaginal infections.
🔹
1) Assessment of Risk Factors:
While the exact cause of preterm labor is often unknown, there is strong evidence thatintrauterine infection may play a role in
every early preterm labor.
3. Frequent antenatal surveillance, including serial ultrasound examinations. -Previous preterm delivery: risk 20- 40%: Of all the predictors of preterm birth,past obstetrichistory is the strongest predictor of
4. Changes of life style. recurrent preterm birth.
5. Oral administration of tocolytic drugs.
6. Progesterone administration.
7. Cervical cerclage. preterm labor -Cigarette smoking
-Reduced body mass index (BMI)- BMI less than 19.0
-Interpregnancy interval of less than one year
🔷
II. Management of threatened or imminent preterm labor (Early warning symptoms):
1. Antibiotics:
-Maternal age (teenage multiparae)
-Nulliparous or grandmultiparous
🔷
It is possible that antibiotics are effective only when treatment is initiated early in theinfectious process.
2. Prophylactic tocolysis:
-Ethnicity (black women)
-Socioeconomic deprivation
🔸
Stopping uterine contractions may prevent further cervical effacement and the loss of the mucous plug.
Different types of tocolytic drugs are used such as:
1)Beta adrenergic agents:
-Unemployment
-Low level of education
2) Microbiological Screening:
act by promoting the extrusion of calcium from the cells. The medications most frequently used are Ritodrine and Terbutaline. Screening and treating lower genital tract and sexually transmitted infection isrecommended prior to and in the first trimester of
According to the Federal Register, Ritodrine was voluntarily withdrawn from the United States market in 2003. Adverse reports describe a sudden maternal death and a newborn with myocardial necrosisafter the mother PREDICTION pregnancy(bacterial,vaginosis,Asymptomatic bacteriuria, Group B streptococcal colonization).
🔻
used the pump for 12 weeks.
Contraindications to the use of intravenous beta-adrenergic agents:
3) Cervical Length Scan:
Vaginal U/S allows a more objective approach to examination of the cervix.When measuredby transvaginal ultrasonography, cervical
length is inversely and continuously related to therisk of preterm birth in both singleton and multifetal pregnancies. A positive
1.Symptomatic cardiac disease. predictive valueof 70% and a sensitivity of 60-80% is observed with a transcervical ultrasound cervical lengthof less than 25 mm
2.Symptomatic cardiac rhythmor conduction disturbance. between 14 and 18 weeks gestation.
3.Hyperthyroidism. 4) Fibronectin Test:
4.Sickel cell disease. This glycoprotein is produced in 20 different molecular forms by various cell types,includinghepatocytes, fibroblasts, endothelial
5. Uncontrolled insulin-dependent diabetes. 6.Chorioamnionitis. cells, and fetal amnion. Present in high concentrationsin maternal blood and in amnionic fluid, it is thought to function in intercellular
7. Eclampsia or severe pre-eclampsia. adhesionduring implantation and in maintenance of placental adherence to uterine decidua.
8.Multifetal gestation. Fetalfibronectin (fFN) is rarely present in the vaginal secretions between 23 and 34 weeks. Anydisruption at the chorio-decidual
9.Severe obstetrical bleeding. interface (before membrane rupture) results in fFN releaseand possible detection in cervicovaginal secretions and was a possible
10.Severe anaemia. marker forimpending preterm labor.
11. Patients on monoamine oxidase inhibitor. Fetal fibronectin is measured using an enzyme-linkedimmunosorbent assay, and values exceeding 50 ng/mL are considered positive.
12. Asthmatic patients already taking beta-adrenergic agents. Sample contamination by amnionic fluid and maternal blood should be avoided.
2)Magnesium salts:
acts by displacing calcium from the myometrial cells. Oral Magnesiumsalts can be given as a prophylaxis in threatened preterm labor.
When there are evidence of imminent preterm labor intravenous Magnesium sulfate is initiated if there is a need to postpone delivery.
intravenous magnesium sulfate-a 4-g loading dose followed by acontinuous infusion of 2 g/hr-usually arrests labor. 1.Maternal:
Recently, the FDA (2013) warned against prolonged use of magnesium sulfate given to arrest preterm labor due to bone thinning and fractures in fetuses exposed for more than 5 to7 days. This was attributed to low Maternal mortality and morbidity as consequences of preterm labor are rare. The most common maternal effects are feeling of
calcium leveIs in the fetus. inadequacy at fulfilling a reproductive role andincrease risk for the development of postpartum endometritis.
🔹
3)Calcium channel blockers: 2.Fetal consequences of preterm labor:
Myometrial activity is directly related to cytoplasmic free calcium,and a reduction in its concentration inhibits contractions. I.Perinatal mortality:
Calcium-channel blockers act to inhibit, by various mechanisms, calcium entry through cell membrane channels. Although they were developed to treat hypertension, their ability to arrest preterm labor hasbeen Preterm delivery is the leading cause of perinatal mortality, responsible for about 75% ofearly neonatal deaths. Perinatal mortality
🔹
evaluated. Investigators have also concluded that calcium-channel blockers, especially nifedipine, are safer and more effective tocolytic agents than are β-agonists.
The combination of nifedipine with magnesium for tocolysis is potentialy dangerous. As nifedipine enhances the neuromuscular blocking effects of magnesium that can interfere with pulmonary and cardiac function
4)Prostaglandin Inhibitors:
🔹
increases markedly as gestational age and birthweight decline.
II.Perinatal morbidity:
Preterm infants are at risk for specific diseases related to the immaturity of various organsystems and the cause and circumstances of
Prostaglandins are intimately involved in contractions of normal labor. preterm birth. Common complications inpremature infants include respiratory distress syndrome (RDS), intraventricular
Antagonists act by inhibiting prostaglandin synthesis or by blocking their action ontarget organs. hemorrhage(IVH),bronchopulmonary dysplasia (BPD), patent ductus arteriosus (PDA), necrotizingenterocolitis (NEC), sepsis, apnea,
🔹
Indomethacin is administered orally or rectally. and retinopathy of prematurity. The frequency of majormorbidity rises as gestational age decreases, especially below 30 weeks.
A dose of 50 to 100 mg isfollowed at 8-hour intervals not to exceed a total -24 hour dose of 200 mg. Serum concentrations usually peak 1 to 2 hours after oral administration, whereas levels after rectal administration III.Long-Term Outcomes:
peak slightly earlier. MANAGEMENT OF PRETERM LABOR Major neonatal morbidities related to preterm birth that carry lifetime consequences includechronic lung disease, grades IlI and IV IVH
Most studies have limited indomethacin use to 24to 48hours because of concerns for oligohydramnios, which can develop with these doses. (associated with cerebral palsy), NEC, and vision and hearing impairment.
If amnionic fluid is monitored, oligohydramnios can be detected early, and it is reversible with drug discontinuation. CONSEQUENCES OF PRETERM LABOR Follow-up studies of infants born preterm and LBW infants reveal increased rates of cerebral palsy, neurosensory impairment,
reduced cognition and motor performance, academic difficulties, and attention deficit disorders.
5)Progesterone:
acts by its antagonistic effect on prostaglandin F2-alpha and its ability toblock the development of gap junction necessary for the propagation of muscular activity.
6)Atosiban: OUTCOMES FOR INFANTS BORN PRETERM
This nonapeptide oxytocin analogue is a competitive antagonist ofoxytocin-induced contractions. In randomized clinical trials, atosiban failed to improverelevant neonatal outcomes and was linked with significant Gestational age at birth is strongly correlated with adverse pregnancy outcomes that include
neonatal morbidity. stillbirth (fetal death after 20weeks' gestation), deaths of neonates (<28 days) and infants
7)Nitric Oxide Donors: (<12months), and long-term physical and intellectual morbidities.
These potent smooth-muscle relaxants affect the vasculature,gut,anduterus. Nitric Oxide Donors like nitroglycerine have been tested as tocolytics,administeredeither intravenously or in form of transdermal patches.
The current RCOG guidelines suggest atosiban and nifedipine as they appear to havecomparable effectiveness in delaying delivery, with fewer maternal side effects than alternatives such as ritodrine or indomethacin.
🔷
Although the use of nifedipine for preterm labour is unlicensed, it has the advantages of less frequent side effects, oral administration and a low purchase price.
3. Antenatal Corticosteroids Administration Current evidence supports the administration of a single course of antenatal corticosteroidsbetween 24 and 34'6 weeks of gestation to enhance fetal lung maturation.
It reduced the risk of neonatal death by 31%, respiratory distress syndrome by 44% and intraventricularhaemorrhage by 46%.
⭐ MAGNESIUM SULPHATE FOR NEUROPROTECTION:
Antenatal magnesium sulphate therapy given to women at risk of preterm birth substantiallyreduced the risk of neonatal cerebral palsy.
There was also a significant reduction in the rate of substantial gross motor dysfunction. It is recognized that the magnitude of the beneficial effect is likely to be higher at earlier gestations and limited at gestations by fatema okoff
above 32 weeks. For this reason and due to concerns over adverse neonatal outcomes reported in an earliertrial, its use above 32 weeks' gestation is not advocated.
The current recommendation is a 4g IV loading dose followed by a maintenance dose of 1 g per hour for 24 h unless precededby birth.
🔹
III. Management of patients with established preterm labor:
1. Identification of patients that needs to be delivered e.g.:
1. Maternal disease: like the presence of hyperthyroidism, chronic hypertension,pre-eclampsia, chronic renal disease.
2. Advanced labor: patients with 5 cm or more, 100% effaced and with membrane bulging.
3. lethal fetal congenital anomalies.
4. Fetal growth restriction.
5. Chromosomal abnormalities.
6. Chorioamnionitis.
🔹
7. Adequate fetal pulmonary maturity.
2.Treatment of patients who need to postpone their delivery:
1) The use of intravenous tocolysis: The main objective of treatment is to keep patientsundelivered for the shorttime necessary for glucocorticoid treatment.
2) Antibiotics.
3) Glucocorticoids.
4) Phenobarbital.
🔶
5) Vitamin K1.
Intrapartum management of preterm labor
1. Frequent or continuous FHR monitoring.
2. Prevention of neonatal GBS infection.
3. CS indicated in any abnormal delivery, or prolongation of the active phase of labor
4. Episiotom y is needed, unless the vulva is patuolous.
5. Prophylactic vitamin K administration to the mother.
6. Prophylactic phenobarbital administration to the mother.
7. The availability of experienced resuscitation and neonatology care.
8. Epidural analgesia are the best for pain relief
