Premature labourAss. Prof.Obst&Gyn. Univ. of Alex.
Gestational Age Terminology
Indiana University
28
* Raju TNK., Higgins RD, Stark AR, Leveno KJ Optimizing Care and Outcome of the Late Preterm (Near-Term) Pregnancy and the Late Preterm Newborn Infant. Pediatrics , 2006;118 1207-14
Slide courtesy of Dr. Tonse Raju, 2007 presentation
abortion
Preterm is less than 37 completed weeks gestation.
Source: National Center for Health Statistics, 2003 natality file. Prepared by the March of Dimes Perinatal Data Center, 2006
13.0%
21.2%
(32 Weeks)
(<32 Weeks)
(35 Weeks)
(36 Weeks) 71% of PTB is at 34, 35, 36 weeks
WHO defined preterm birth as any birth regardless of birth
weight which occurs up to 37th
menstrual weeks gestation
Low birthweight is less than 2,500 grams (5 1/2 pounds). Preterm is less than 37 completed weeks gestation.
Source: National Center for Health Statistics, 2003 natality file. Prepared by the March of Dimes Perinatal Data Center, 2006.
Overlap in LBW, Preterm & Birth Defects
Low
Birthweight
Births
7.9%
Preterm
Births
12.3%
LBW)
Epidemiology
• preterm labour ….. 12% of all deliveries…. Responsible for 75-90% of all neonatal deaths.
• Main causes of neonatal morbidity & mortality; Organs immaturity , RDS ,PDA , necrotizing enterocolitis , hyperbilirubinemia , IVH , retinopathy of prematurity & neonatal sepsis
• Long term problems… CP,MR,SNHL
WHO
• Every year, an estimated 15 million babies are born preterm (before 37 completed weeks of gestation)
• the rate of preterm birth ranges from 5% to 18% of babies born.
• WHO,November 2016
WHO 2016
The 10 countries with the greatest number of preterm births: • India: 3 519 100 • China: 1 172 300 • Nigeria: 773 600 • Pakistan: 748 100 • Indonesia: 675 700 • The United States of America: 517 400 • Bangladesh: 424 100 • The Philippines: 348 900 • The Democratic Republic of the Congo: 341 400 • Brazil: 279 300
WHO 2016
There is a dramatic difference in survival of premature babies depending on where they are born. For example, more than 90% of extremely preterm babies (<28 weeks) born in low-income countries die within the first few days of life; yet less than 10% of babies of this gestation die in high-income settings.
PTL per year
0
2
4
6
8
10
12
10.6 11 11
11.4 11.8 11.6
1. General disease of the mother….DM, anaemia. Heart disease…
2. Specific disease of pregnancy…PET, erythroblastosis fetalis
3. Local disease in genital tract… fibroids, cx incontinence, uterine anomalies
4. Trauma to abdomen
6.Antepartum hge
11-iatrogenic prematurity
14-short interpregnancy intervals
Pathophsiology
Term Labor Preterm Labor
• The exact ….Unknown… even the initiator of NVD still unknown
• ↑ PG….. CX ripening…. Formation of gap junctions…… ↑oxytocin receptors…… myometrial contraction
“Progesterone deficient state” has been proposed to be a Mechanism of
Disease in Preterm Labor
Progesterone in Pregnancy Maintenance
A progesterone withdrawal “prepares” the uterus
for the action of uterotonic agents
Common Terminal Pathway
Normal Term Labor
Diagnosis
Recurrent PTL(15-40%) or 2nd trimester abortions (50%). While 1st trimester associated with 12% increased risk
I. Digital cx examination
II. Sonographic cx evaluation
IV. Fetal fibronectine
V. Urogenital infections
Digital CX examination
• Avoid infection…..in PROM
• Cx anatomy…..length(25-45mm), IO diameter, funneling
Transvaginal Cervical Sonography
Source: Reprinted from Ultrasonography in Obstetrics and Gynaecology, 4th ed., Callen PW,
Copyright 2000, with permission from Elsevier.
Cervical Effacement = T Y V U
Source: Zilianti M et al. Monitoring the effacement of the uterine cervix by transperineal sonography: a new perspective. J
Ultrasound Med 1995;14:719-24. Reproduced with permission from the American Institute of Ultrasound in Medicine.
T Y
Mechanism of Effacement:
• At home
• External tocodynamometers
• Pattern of uterine activity is assessed
• Once abnormal finding…..physcian
Window of opportunity
• Increase in frequency of uterine contraction from 24-48 hrs before the onset of true labour
• So early tocolysis could be used before overt PTL
Fetal fibronectin
• Fibronectins are group of proteins found in plasma ,extracellular tissue & amniotic fluid
• Plasma fibronectin…. Regulate oncotic pressure, coagulation & bacterial opsonization
• Fetal fibronectin found in basesment membrane near choriodecidual interface… adhesive binding of placenta & membranes to decidua
• Fibronectin in the stroma of the cx is differ than fetal fibronectin
• Fetal fibronectin…. Found in cervicovaginal secretion before 20 wks & near FT
• So clinical detection at 22-34 wks at concentration 50mg per ml considered abnormal & indicates choriodecidual disruption
• Also presence of fetal fibronectin in the vagina…… leakage of AF
Urogenital tract infection
• Urogenital tract infection or inflammation….. May be associated with PTL
• Untreated asymptomatic bacteruria…. Pyelonephritis……PTL
• Chorioamnionitis….. PTL
Specific criteria to diagnose PTL:
painful uterine contractions, 4 in 20 minutes or 8 in 60 minutes,
AND
Classification of Preterm Birth
– Preterm premature rupture of membranes (PPROM)
– Multiple gestation
– Cervical insufficiency
b) Clinically Indicated - 25% – Mother or fetus at risk
Sources: Goldenberg RL et al. Am J Public Health 1998;88:233-8; Meis PJ et al. Am J Obstet Gynecol
1995;173:597-602; Meis PJ et al. Am J Obstet Gynecol 1998;178:562-7.
a)Threatened b)Actual 85 % of pt with threatened PTL…Deliver at FT
40-50% of pt with actual PTL….deliver at FT
• Preeclampsia 43%
• Abruption 7%
• Fetal demise 7% Source: Meis PJ et al. Am J Obstet Gynecol 1998;178:562-7.
Clinical Indications for Preterm Deliveries
The Morbidity of Prematurity
Transient dystonia
Source: Iams JD, Creasy RK. Preterm labor and delivery, Chapter 34.
In: Maternal-Fetal Medicine: Principles and Practice, 5th ed., 2004.
Management of preterm labour
II. Labour in equipped hospital
III. Prevent rapid compression decompression syndrome …. use episiotomy , forceps ….. donnot use vacuum
IV. Vigrous care to fetus
V. CS….prolonged labour , fetal or maternal distress , abn.presentations
Curative treatment
1. Bed rest & sedatives …PTLP without PROM.. .. LATERAL LYING position 2-3 days …… adequate sedations like; diazepam ,pethidine
2. Tocolytic agents .. relax.uterine contraction .start by IV followed by oral or IM
3. Maternal CST .. Acceleration of fetal lung maturity …dec.RDS
TOCOLYTIC AGENTS
• Effective in prolongation of pregnancy
Because of the poor bioavailability of progesterone when taken by mouth, many synthetic progestins have been designed with improved bioavailability by mouth and have been used long before progesterone formulations became available
uses of progesterone include hormone replacement therapy, prevention of preterm birth and miscarriage, fertility support, and treatment of gynecological conditions.
• Pure crystalline progesterone was isolated in 1934 and its chemical structure was determined
• Later that year, chemical synthesis of progesterone was accomplished.
• Shortly following its chemical synthesis, progesterone began being tested clinically in women.
• Micronization, allowed progesterone to be absorbed effectively via other routes of administration, but the micronization process was difficult for manufacturers for many years.
• OMP was finally marketed in France under the brand name Utrogestan in 1980,and this was followed by the introduction of OMP in the United States under the brand name Prometrium in 1998. In the early 1990s, vaginal micronized progesterone (brand names Crinone, Utrogestan, Endometrin)was also marketed
Progesterone was approved by the United States Food and Drug Administration as a
vaginal gel on 31 July 1997, a capsule to be taken by mouth on 14 May 1998, in
an injection form on 25 April 2001, and as a vaginal insert on 21 June 2007.
Synthetic progestinsNatural micronized progesterone Plant source……..like soya beans
High bioavilability; more rapid max. serum conc. Increased half – life VS natural progesterone
High bioavilability; more rapid max. serum conc. Increased half – life VS natural progesterone
Water retention, inc.Na conc.Dec. water retention; balances Na content
Inhibits ovulation,birth control,birth defects
May cause depressioneuphoric
Breast tenderness,insomnia,nausea,skin rash
Inhibits libidoInc.libido
Inc.HDL, stimulate bone building
May cause migrainRelieve premenstrual migrain
Beta sympathomimetic agent
Beta adrenergic receptors……. Beta 1… found in heart, small intestine & adipose tissues
While beta 2…. Found in uterus, bld vessels, bronchioles & liver
SE:
Ritodrine …. 1st drugs approved by FDA ,oral , iv infusion
Terbutaline …..less SE, SC,oral
PG synthetase inhibitors • One of the most effective drugs for
treatment of PTL
• Safe to women…. Narrow window of safety for the fetus
• Indomethacin …. Most common
• Oral or rectal
SE:
GIT C.O, premature closure of ductus arteriosus, , fetal death, oliguria ,oligohydramnios, hyperbilirubinemia,
Magnesium sulfate 2nd most common parentral tocolytic
agent after B2 agonist
SE: Loss of deep reflexes, pulmonary oedem, Respiratory depression, cardiac arrest, paralysis, Dec. fetal heart rate variability, Dec.fetal breathing movement, Hyporeflexia, falaccidity
nifedipine Ca channel blocker=ca antagonist
Used to normalize excessive ms contractlity
SE:
Oxytocin receptor blockers The concentration of oxytocin receptors
increases with gestational age and reaches the maximum just before and during labour
Atosipan; specific competitive inhibtor of oxytocin binding receptors
SE; N,V,headache,chest pain
• Rapid onset,short duraion of action
Contraindications to tocolysis
IV. Chorioamnionitis
II. IUGR
V. Significant maternal disaes
VI. Cx dilatation ≥5cm
VII. Progressive structural but not lethal anomalies in the fetus
CST • Dec. RDS, IVH, NEC & neonatal death
• Inc. neonatal sepsis