Preterm Delivery

Question 1

Definition

Answer 1

delivery completed between 24 – 36 weeks +6 days of gestation.

Question 2

Spontaneous preterm labor

Causes

Answer 2

PPROM
Spontaneous preterm labor
Iatrogenic intervention
Polyhydramniose.
Multiple pregnancy
Placental abruptiong.
Incomplete cervix
Infection (promote PROM by toxin-mediated tissue destruction)

Previous history

Social factors – poverty, maternal age, stressful work, smoking.

Question 3

Preterm infant Survival and complications

Answer 3

Each day of delay in birth after 24 weeks increases survival by 5%

b. Infants less than 500g have little chance of survival

c. Infants around 1500g have high chance of survival as a full-term infant.

d. Complications:

Complications:

i. Respiratory infection

ii. Necrotizing enterocolitis

iii. IRDS

iv. Periventricular hemorrhage

v. Jaundice – treated by phototherapy (photo-oxidation) which makes bilirubin dissolve faster in water.

vi. Hypoglycemiavii. Hypothermia

Question 4

Preterm delivery management

Answer 4

1. Avoid heavy work and excessive physical activity during pregnancy
2. Treatment of asymptomatic bacteriuria with antibiotics
3. Women with short cervix (<2.5 cm) can:

a. Take progesterone (reduces incidence of delivery)

b. Undergo cervical cerclage (cervical stitch) although barely has benefit.

4. Postponing delivery for administration of corticosteroids to allow fetal lung to produce surfactant and reduce chance for IRDS and HMD (hyaline membrane disease).
5. Tocolysis is contraindicated in case of bleeding to avoid hemodynamic instability of the mother.
6. Groups of drugs used to delay labor

Question 5

Groups of drugs used to delay labor

Answer 5

Beta agonists
COX1/2 reversible inhibitors
Magnesium-sulphate
Ca2+ channel blockers
Corticosteroids

Question 6

Beta agonists to delay labor

Answer 6

i. Mechanism: increase in intracellular cAMP which downregulates MLCK and inhibits uterine activity.

ii. Agents: ritodrine, salbutamol, terbutaline

iii. Usage: diluted in saline and infused to the mother with increased rate every 10-20 minutes until contractions are reduced to one every 15 minutes.

iv. Complications: pulmonary edema, hypokalemia, hyperglycemia, arrhythmia

Question 7

COX1/2 reversible inhibitors

Answer 7

i. Agents: indomethacin

ii. Usage: 1-3mg/kg for 24 hours or minimum dose for 1-3 days to avoid complications.

iii. Complications: closure of ductus arteriosus, oligohydramnios

Question 8

Ca2+ channel blockers

Answer 8

i. Agents: nifedipine

ii. Usage: oral dose of 20mg followed by 10-20mg every 4-6 hours.

Question 9

Corticosteroids

Answer 9

i. Agents: betamethasone, dexamethasone

ii. Usage: 12mg every 12 hours IM injection for up to 7 days.

Question 10

Method of delivery

Answer 10

a. It is rare to inhibit labor when gestation is over 34 weeks because the benefits of intervention overcome those of inhibition.

b. Head/vertex presentation – preferred is gentle vaginal delivery and only if necessary,the use of forceps.

c. Breech presentation – C-section (unless gestation is over 34 weeks) because the head is bigger than the trunk and it might get stuck if the cervix is not dilated enough and cause compression of head leading to intracranial hemorrhage.