Management of Pre-term labour

Maternal steroid

Current recommendation of :

12mg Betamethasone 2 doses, 24 hrs apart OR
6mg Dexamethasone 4 doses, 6 hrs apart

Given during 28-34th week of pregnancy, within 7 days of delivery is said to improve the outcome. Betamethasone is actually more superior than dexamethasone since it more readily crosses the placental barrier as compared to dexamethasone.


However, both requires 48 hrs to achieve maximum benefits. But if it's given before 48 hrs or more than 7 days before delivery, it is still beneficial.

It prevents fetal respiratory distress since it promotes lung maturation.

Tocolytics

Examples of tocolytics :

Ritodrine, Magnesium Sulphate, Nifedipine, and GTN.

According to the latest clinical studies, all the above tocolytics doesn't prolong pregnancy till term and do not improve the overall perinatal mortality rates.

However, Ritodrine is still used for short term prolongation, since it has been proven to reduce incidence of delivery within 48 hrs by 40%.

Bear in mind that B-agonist such as Ritodrine may have major adversity over the maternal's cardiorespiratory system.

Antibiotics

Many clinicians are having similar opinion that routine antibiotics for uncomplicated pre-term labour doesn't confer any benefits. However, a 10 day course of erythromycin is said to improve the outcome in management of preterm-prelabour rupture of membrane (PPROM).

Fetal assessment

Preterm infants has less reserve to tolerate the process of delivery.
Maternal steroids may suppress the fetal activity and baseline rate, hence a continuous fetal assessment is required.(CTG)

For pre-term infants <34 weeks -> obtain the estimated fetal weight
To determine the presentation, lie -> by palpation is unreliable, should be determined by USG

Mode of delivery

Though the high morbidity/mortality, maternal risks, and difficulty in determining intrauterine hypoxia/acidosis, still a C-section is not really an indication for POG < 26 weeks.

However, in case of pre-term breech vaginal delivery, C-section is done.

Type of C-section

A classical C-section by vertical incision is required, since in during pre-term period, the lower segment is poorly formed, and may be occompanied by oligohydramnios. Bear in mind that the classical C-section carries about 5% risk of uterine rupture.

Analgesia

Epidural anasthesia is done.

Management of high risk asymptommatic women

Prevention of prematurity is mainly focused on pregnant mothers, who is though asymptommatic, but is having various risk factors for pre-term birth.

After a pre-term birth, investigation is done to determine what are the possible events leading to it. (for example -> placental pathology)

Ideally, a management plan for subsequent pregnancy is formed.

a) Early dating scan

To accurately determine the period of gestation

b) Bacterial vaginosis

Bacterial vaginosis is associated with risk of miscarriage and pre-term birth. Hence, screening for bacteral vaginosis is done in suspected cases. A course of clindamycin and metronidazole during antenatal period significantly reduces the incidence. However, it's only beneficial in high risk cases.

c) Asymptommatic Bacteriuria


Most of the cases of asymptommatic bacteriuria will eventually progress to UTI and pyelonephritis.
Short courses of antibiotics should be given according to the Culture's sensitivity.

d) Fetal fibronectin

Fetal fibronectin provides rapid assessment for women with minimal cervical dilatation, or in symptommatic women for pre-term labour.
Only done after 23rd week of pregnancy (as <23 week, high levels may be physiological)

e) Ultrasound

This is to determine the cervical length, which the average value is 35mm.
Any value <35mm is associated with risk of pre-term labour.
If significant short cervical length is found in POG <24 weeks is an indication to perform cervical cerclage.

f) GBS colonisation of genital tract

Most of the pre-term infants having early onset of sepsis accquires GBS infection through the contaminated birth canal. To reduce such incidence, during antenatal period, vaginal/rectal swabs are obtained and intrapartum prophylaxis can be given later.

Category: Obstetrics Notes