Preterm, late-term, and postterm pregnancies

Triono Adisuroso MD, SpOG, MMed, MPhil

Preterm birth

�  Birth occurs < 37 weeks (20+0/7 – 36+6/7 weeks)

�  Multifactorial

�  Incidence: 12.5% in the US

�  70% of perinatal mortality and 30-50% of long-term neurologic impairment

�  Preterm birth: spontaneous and indicated

Epidemiology

Uterine components of parturition pathway

Preterm parturition syndrome

Preterm causes

Maternal risk factors

�  Race/ethnic: blacks 16-18%, whites 5-9%, developed countries < developing countries

�  Interpregnancy interval <6 months is 2-fold increased risk for PTB

�  Maternal nutrition status

Pregnancy history

�  Recurrent risk: 15-50% - mechanism is not clear

�  Previous PTB led 2.5 increased risk for next pregnancy

�  Spontaneous PTB is more likely to subsequent spontaneous PTB

�  Persistent intrauterine infection increases repetitive spontaneous PTB

�  Underlying disorders causes indicated PTB: hypertension, diabetes, or obesity

Pregnancy characteristics

�  Multiple pregnancy: 15-20% of all PTBs

�  Nearly 60% of twins are delivered preterm

�  40% of twins have spontaneous PTB or PPROM

�  Uterine overdistension resulting in contractions and PPROM causes spontaneous PTB

�  Vaginal bleeding due to placenta previa or placental abruption

�  Polyhydramnios or oligohydramnios

�  Maternal surgery in 2nd and 3rd trimester leads to contractions

�  Maternal medical disorders

�  Maternal psychosocial stress had <2-fold increased risk of PTB

�  Clinical depression

�  Smoking, alcohol, and elicit drugs

�  Intrauterine infections related to innate immune system activation and result in 25-40% of PTB

�  Microorganism access to amniotic cavity:

�  1. ascending infection (common pathway)

�  2. hematogenous

�  3. accidental introduction

�  4. retrograde

�  Bacterial vaginosis (BV): 1.5-3-fold increases PTB

�  Other genital infections: chlamydia, syphilis, gonorrhea

�  Non-genital tract infections

�  Cervical insufficiency;

-  Cervical length abnormality: <25 mm

-  Cervical incompetence

-  Uterine abnormalities: didelphys. bicornu, septum

-  Cervical surgery: LEEP, LLETZ, conization

Short cervix

Biological and genetic markers

�  Biological fluid: amniotic fluid, cervical mucus, vaginal secretions, urine, serum, plasma, saliva)

�  Cytokines, chemokines, estriol, and other analytes – related to inflammation – associated with PTB

�  Fetal fibronectine (fFN)

-  A glycoprotein in cervicovaginal fluid

-  Absent >24 weeks

-  The most predictor for PTB

Roles of genetic components

�  PTL and PPROM related to genetics

�  80% higher risk of having PTB in women with sisters having PTB

�  SNP associated with PTL and PPROM

�  TNFα gene and BV

�  IL6 allele and BV

�  Proteome (protein encoded genome) related to PTB

Clinical manifestations of PTB

Clinical presentations -  Preterm labour -  PPROM -  Cervical insufficiency -  Amnionitis -  Vaginal bleeding

Causative mechanisms -  Infections -  Hemorrhage -  Uterine distention -  Trauma -  Fetal compromise

Risk factors -  Multiple pregnancy -  Placental abruption -  Preeclampsia -  Diabetes -  Hypertension -  Pyelonephritis

Diagnosis and management Diagnosis

�  Diagnosis of PTB is challenging such as gestational age and clinical manifestations

�  Accurate diagnosis is difficult because signs and symptoms similar to normal pregnancy

�  Cervical dilatation

�  Cervical length: Transvaginal US > transabdominal US, Elastography

�  Fetal fibronectin (fFN) of cervicovaginal fluid

Management

�  Treatment to reduce mortality and morbidity

-  Antenatal corticosteroids

-  Antibiotics

-  Neuroprotectants

-  Progesterone

-  Cervical cerclage

�  Tocolytic therapy

-  To reduce uterine contractions

-  Tocolytic agents: Ca-channel blockers, NSAIDs, Cyclooxygenase inhibitors (COXs), Betamimetic tocolytics, oxytocin antagonists, MgSO4

Cervical cerclage and elastography

Prevention of PTB �  Routine prenatal care

�  Access to prenatal care

�  Nutrition

�  Smoking cessation

�  Periodontal care

�  Screening to reduce risks: asymptomatic bacteriuria, genital infections, fFN, CL assessment, combined test

Late-term and Post-term

Definition and incidence �  Based on LMP

-  Late-term: 41 weeks + 0 day – 41 weeks+6 days

-  Post-term: ≥42 weeks + 0 day

�  4-14% of post-term

�  2-4% reach 43 weeks

�  5% giving birth at 40 weeks

�  Accurate determination of gestational age for accurate diagnosis and appropriate management to

�  Antenatal fetal surveillance and induction to decrease perinatal mortality and morbidity

Pathogenesis �  Integration and synchrony of multiple factors:

-  Fetal hypothalamic-pituitary-adrenal axis

-  Placenta and membranes

-  Myometrium and cervix

�  Fetal pituitary defects

�  Fetal adrenal hypoplasia

�  Placental sulfatase deficiency leads to low estrogen resulting in delayed onset of labour and cervical ripening

Etiology factors �  Unclear

�  Primipara > multipara

�  Previous post-term

�  Carrying a male fetus

�  Maternal obesity

�  23-30% of genetic factors

�  Fetal abnormalities: anencephaly and placental sulfatase deficiency

Perinatal risks �  Perinatal morbidity and mortality

�  Abnormal fetal growth

-  Macrosomia – birth injuries

�  Meconium and pulmonary aspiration syndrome

�  Neonatal convulsions

�  A 5-minute low Apgar score (<4)

�  Increase NICU admission

�  10-20% of post-maturity syndrome: lacks of subcutaneous fat, fernix, lanugo, meconium staining in amniotic fluid, skin, membrane, and umbilical cord

�  Olygohydramnios

�  Stillbirth

Perinatal morbidity and mortality

Maternal risks

�  In association between maternal and obstetric complications:

-  Severe perineal laceration

-  Infection

-  Postpartum hemorrhage

-  Caesarean delivery

Management �  Antenatal fetal surveillance

-  Biophysical profile (BPP)

-  Non-stress test (NST)

-  Contraction stress test (CST)

-  AF evaluation

�  Induction of labour

BPP

Thank you