Infection & Preterm Birth

Objectives Understand magnitude of problem of PTB. Gain understanding of role of infection in spontaneous PTB. Overview of clinical decision making and “art” of medicine regarding PTB.

Rate of PTB ~ 10% and increasing Primary cause of neonatal morbidity and mortality Pregnancy is usually seen as a time of exciting anticipation with the expectation that after 9 months the woman will give birth to a healthy beautify baby. Unfortunately, that is not always the case. About 10% of pregnancies are delivered before completing 37 weeks of gestation. Preterm birth, defined as delivery before completion of the 37th week of gestation, is the number one cause of neonatal morbidity and mortality.

Economic Impact of PTB Hospital costs for preterm infants. Does not include cost of ongoing care of a disabled child

Risk Factors for Preterm Delivery Previous obstetric history Race/ethnicity Multiple gestation Incompetent cervix Congenital Anomalies

Risk Factors for Preterm Delivery Substance abuse Pre-Pregnancy Weight Stress Maternal Age INFECTION

Infection and PTB 40% of PTB due to infection ↓ Gestational Age Infection Only pathologic process with firm causal link established Fetal infection & inflammation  Cerebral palsy & chronic lung disease IUI and Inflammation are frequently associated with PTL and delivery and at least 40% of all PTB are estimated to occur with mothers who have an IUI which is largely subclinical. The lower the GA at delivery, the greater the frequency of IUI.

Infection & PTB: Pathophysiology Invasion of Amniotic Fluid Fetal Invasion Localized Inflammatory Reaction Stages of ascending IUI Change in vaginal and cervical microbial flora or presence of pathologic organisms in the cervix 2. Microorganism spreads up to the chorion and amnion to reside in decidua and a localized inflammatory reaction Change in flora

Case Study 1 24 yo at 23 weeks EGA with gush of fluid Bacterial vaginosis diagnosed on vaginal exam Admitted, antibiotics started, counseled Family opts for expectant management Counseling – options – then she develops fever and abdomenal tenderness Next pregnancy

Case Study 1 Develops fever and uterine tenderness Contractions increased Vaginal delivery of 800 gm baby boy Severe respiratory distress, multi-organ system failure.

Case Study 2 34 yo at 35 weeks with contractions and cervical dilation. Group B Strep isolated from vagina at last prenatal visit. Management options

Case Study 2 Amniocentesis showed mature fetal lungs Antibiotics continued Vaginal delivery Baby weighted 5#5oz; stayed in nursery for 5 days then discharged to home. No long term sequelae.

Case Study 3 30 yo at 26 weeks presenting with flu-like illness, rash, vaginal discharge and uterine cramping. Management options – keep mother from getting too ill with IV antivirals. Primary Genital Herpes

Case Study 3 Intravenous anti-viral medication Tocolytics to relax uterus Contractions continued and membranes ruptured Cesarean delivery of 2.5# infant

Case Study 3 Support in NICU IV antivirals Spinal tap Disseminated HSV