Prematurity Labor, Delivery Muruvet Elkay, MD PL-II 12/16/2005
Objectives • Epidemiology • Risk factors • Infection • Role of antenatal steroids • Complications • Management
Preterm Labor • Preterm labor (PTL): Presence of contractions which cause progressive effacement and dilatation of the cervix between 20 and 37 weeks’ gestation. • Preterm birth (PB): Occurs in 6-8% of pregnancies. The incidence has remained stable for more than 25 years. Ref: eMedicine Sep 22, 2004: Preterm Labor: Article by Edward R. Newton, MD
Terms Related to Prematurity • Premature infant: An infant born before 37 weeks of estimated GA. • Low birth weight (LBW): BW<2,500 g • Very low birth weight (VLBW): BW<1,500 g • Extremely low birth weight (ELBW): BW<1,000 g • Chronologic or birth age: Time since birth. • GA: Estimated time since conception; postconceptional age. • Corrected age: Age corrected for prematurity. Ref: David E. Trachtenbarg etal. American Family Physician 1998; 57 (9): 1-11
The Epidemiology of Preterm Birth • Racial differences in the rate of preterm LBW VLBW African-American women 13.0% 3.1% Asian-Pacific Islanders 7.3 1.0 Native Americans 6.8 1.2 Whites 6.5 1.1 Hispanics 6.4 1.1 • In a twin, triplet or higher order multiple gestation: 23 % of LBW infants Ref: Jay D. Iams, Clin Perinatol 30 (2003) 651-664.
US Incidence of Preterm Birth 1992-2002 Ref: Edward R. Newton: Clin Perinatol 32 (2005) 571-600.
Neonatal Morbidity and Mortality by Gestational Age Ref: Edward R. Newton: Clin Perinatol 32 (2005) 571-600.
Hospital Charges by Gestational Age of Delivery Ref: Edward R. Newton: Clin Perinatol 32 (2005) 571-600.
Etiology of Preterm Birth • Physician-initiated birth (indicated PB): a. Pre-eclampsia 40% b. Fetal distress 30% c. IUGR 10% d. Abruption placenta or placenta previa 10% e. Fetal death 5% • Spontaneous PB: a. Preterm labor (PTL) b. Preterm premature rupture of membranes (PPROM) Ref: Edward R. Newton: Clin Perinatol 32 (2005) 571-600
PTL Previous PB Low body mass Poor weight gain Heavy work load Uterine abnormalities Drug abuse, smoking PPROM INFECTION Uterine distension Cervical incompetence African-American Low socioeconomic class Drug abuse, smoking Risk Factors for PTL and PPROM Ref: Edward R. Newton: Clin Perinatol 32 (2005) 571-600.
The Strong Association Between Infection and Preterm Birth • Incidence of subclinical histologic chorioamnionitis: 50% 24 to 28 weeks 10% >37 weeks • The smaller the fetus, the more likely the chorioamnion cultures are positive: 80% <1000 g 30% >2500 g Ref: Edward R. Newton: Clin Perinatol 32 (2005) 571-600.
Relation of Infection and Preterm Birth Genome Uteroplacental Insufficiency Bacteria, Virus, Protozoa Maternal Stress Fetal Stress Infection:Leukocyte Response ↓Progesterone Inhibition ↑TOLL 4 Receptors Cytokine Cascade:↑TNF, ↑IL6, ↑ IL8, etc Genome Decidual Activation Phospholipase A, prostaglandins, lysolethecin, mettaloproteinases, collagenases, elastases..
Phospholipase A, prostaglandins, lysolethecin, mettaloproteinases, collagenases, elastases.. Preterm Labor Rupture of Membrane Cervical Incompetence PRETERM BIRTH Ref: Edward R. Newton: Clin Perinatol 32 (2005) 571-600
Risk Factors for Infection-Related Preterm Birth • Historical: Idiopatic PL, PROM History of UTI and STI • Behavioral: Unintended pregnancy Unmarried Multiple partner • Signs and symptoms: Vaginal discharge Dysuria, dyspareunia Ref: Edward R. Newton: Clin Perinatol 32 (2005) 571-600.
Prophylactic Antibiotics to Prevent Preterm Birth GBS • Incidence of vaginal GBS- 20-25%. • No association between vaginal GBS and PB. • Prophylactic antibiotics are not indicated for recto-vaginal colonization of GBS. • Antepartum treatment of GBS in urine. Ref: Edward R. Newton: Clin Perinatol 32 (2005) 571-600.
Therapeutic Antibiotics for Infection-Related Preterm Birth GBS: Antepartum treatment of all the women with the risk factors: • Maternal colonization • Previous infant who had GBS sepsis • Antenatal GBS asymptomatic bacteriuria • ROM >12 hrs • Intrapartum fever (probable chorioamnionitis) • GA < 37 wks Ref: Edward R. Newton: Clin Perinatol 32 (2005) 571-600.
Antibiotics for Inhibiting PL with Intact Membranes • Antibiotics are not recommended. Ref: Edward R. Newton: Clin Perinatol 32 (2005) 571-600.
Antibiotics for PPROM • Risk of chorioamnionitis- 20% between 28 and 34 weeks. • Antibiotics are recommended in nonlaboring women. Ref: Edward R. Newton: Clin Perinatol 32 (2005) 571-600.
Chorioamnionitis • Inflammation or infection of the placenta, chorion, and amnion. • Histologic, subclinical chorioamnionitis: >50% of preterm deliveries <20% of term deliveries • Clinical chorioamnionitis: 5% to 10% of preterm deliveries 1% to 2% of term deliveries Ref: Rodney K Edwards: Obstet Gynecol Clin N Am 32 (2005) 270-296.
Clinical Chorioamnionitis • Most frequent identifiable cause of PL. <30 weeks 50% PPROM 40% PL with intact membranes 30% Maternal fever in the peripartum 10% to 40% • Polymicrobial. Ref: Rodney K Edwards: Obstet Gynecol Clin N Am 32 (2005) 270-296.
Clinical Chorioamnionitis Diagnostic criteria: Maternal fever of greater than 100.4 F and at least 2 of the following conditions: • Maternal leukocytosis (>15,000 cells/cubic mm) • Maternal tachycardia (>100 bpm) • Fetal tachycardia (>160/bpm) • Uterine tenderness • Foul odor of the AF Ref: Rodney K Edwards: Obstet Gynecol Clin N Am 32 (2005) 270-296.
Neonatal Outcomes of Chorioamnionitis • Intraventricular hemorrhage • Periventricular leukomalacia • Cerebral palsy • Increased rates of bacteremia • Clinical sepsis • Increased mortality • Low Apgar scores • Hypotension • The need for resuscitation at the delivery • Neonatal seizures Ref: Rodney K Edwards: Obstet Gynecol Clin N Am 32 (2005) 270-296.
Antenatal Steroids • Indicated in the delivery of a fetus at 24-34 weeks’ gestation in the absence of clinical infection. • Delay of delivery- A minimum of 12 hours. • Duration of benefits-7 days or more? • Betamethasone or Dexamethasone? • Reduces the incidence of IVH and NEC. • An adverse impact of multiple courses on fetal growth and development. Ref: eMedicine Sep 22, 2004: Preterm Labor: Article by Edward R. Newton, MD.
Benefits of Antenatal Steroids Last 7 Days or More? • 197 neonates • Group I: 98 delivered within 7 days Group II: 99 delivered more than 7 days • Group I: Lower incidence of receiving respiratory support more than 24 hrs. • No significant differences between the groups in other measures of neonatal morbidity. Ref: Alan M. Peaceman et al. Am J Obstet Gynecol 2005; 193, 1165-9.
Betamethasone or Dexamethasone • 201 preterm singleton infants • GA between 24 and 34 weeks • Neurodevelopmental outcome at 2 years corrected age • Results: Multiple antenatal courses of DEXAMETHASONE associated with an increased risk of leukomalacia and 2-year infant neurodevelopmental abnormalities. Ref: Spinillo A et al. Am J Obstet Gynecol 2004;191 (1): 217-24.
Complications of Premature Infants • RDS • IVH • NEC • ROP • CLD (BPD) • Infection • Anemia • PDA • Apnea • Cryptorchidism • Inguinal hernia • Umbilical hernia
SGA and IUGR: Are They Synonymous? • SGA: Birth weight below the 10th percentile for GA or > 2 standart deviations below the mean for GA. • IUGR: A process that causes a reduction in an expected pattern of fetal growth. 1. Symmetric IUGR 2. Asymmetric IUGR (head-sparing IUGR): • All IUGR infants may not be SGA (Ponderal index). Ref: Utpala G et al: Pediatr Clin N Am 2004;51: 639-654.
Neonatal Complications of IUGR or SGA • Metabolic disorders: Hypoglycemia, hypocalcemia • Hypothermia • Hematologic disorders: polycytemia • Hypoxia: birth asphyxia, meconium aspiration, persistent fetal circulation • Congenital malformation Ref: Utpala G et al: Pediatr Clin N Am 2004;51: 639-654.
Long-term Complications of IUGR or SGA • Cardiovascular disease • Hypertension • Type 2 diabetes Ref: Utpala G et al: Pediatr Clin N Am 2004;51: 639-654
A Premature Infant may be a SGA or IUGR Infant Also- Double Jeopardy! • An adverse outcome resulting from both immaturity and deficient intrauterine growth. • Increased risk for mortality and major neonatal morbidities, including RDS, BPD, ROP, and NEC. • Intensified complications of prematurity by the effect of suboptimal fetal growth. Ref: Rivka H. Regev et al: Clin Perinatol 2004; 34: 453-473.
Delivery room management Temperature and humidity control Fluids and electrolytes Blood glucose Calcium Nutrition Respiratory support Surfactant PDA Transfusion Skin care Other special considerations Management of Premature Infants
THANK YOU Special Thanks to Dr. Manuel V. and Colin Bird MSIII