Preterm labour:
Objectives:
Preterm labour is the first cause of
neonatal morbidity &mortality in Iraq.
WHO 20% death in Iraq.
Timely diagnosis decrease
complications. It’s causes&risks.
DX. History &exam.
Investigations, s. fibrinoctin &cervical
length.
Treatment 0ptions:conservative or
delivery.
Preterm labour:
is the presence of uterine
contractions of sufficient
frequency and intensity to effect
progressive effacement and
dilation of the cervix prior to term
gestation (between 20 and 37
weeks of gestation).
Incidence:
Preterm labour precedes half of
preterm births .
In UK 10% of pregnancies.
In the United States 7%.
It exceeds 15% in some
developing countries.
Fifteen Million neonate deliver
preterm per year over the world.
WHO estimated death under 5
due to prematurity in Iraq 20%,
three quarter could be
prevented.
Aetiology and Risk factors:
It can affect any pregnancy and many women
have no known risk factors.
Risk factors:
•Previous preterm labour .
•or premature rupture of membrane , particularly
in the most recent pregnancy or in more than
one previous pregnancy.
Late Second trimester loss.
Cervical trauma(surgery ,cone
biopsy LLETZ).
Have now short cervix (less
than25mm)by U/S.
•Age:
Teenagers &over thirties increased risk of PTL.
•First pregnancy
•Over-distended Uterus associated with
multiple pregnancy as twin, triplets or
polyhydramnios.
• problems with the uterus, cervix or placenta
such as uterine anomalies, cervical
incompetence, placental abruption.
•Infection:
•Certain infections of genital tract like
bacterial vaginosis caused by
Gardenella vaginalis.
•Smoking, alcohol or illicit drugs.
•Poor nutrition Being underweight or
overweight before pregnancy, or gaining too
little or too much weight during pregnancy.
•Stressful life events, such as the death of a
loved one.
•Domestic violence or any form of abuse
during pregnancy.
•Multiple miscarriages
Some chronic conditions, like hypertension
and diabetes.
•Pregnancy complications, such as
preeclampsia,vaginal bleeding.
•Presence of a foetal birth defect or foetal
death.
•Little or no prenatal care.
•An interval of less than six months since the
last pregnancy.
Specific risks for the preterm neonate:
Preterm infants usually show physical
signs of prematurity in reverse
proportion to the gestational age. As a
result there are medical problems
affecting different organ systems.
Respiratory problems are common;
specifically the respiratory distress
syndrome (RDS or IRDS).
Another problem can be chronic lung
disease (previously called broncho-
pulmonary dysplasia).
•Intra-ventricular haemorrhage:
• it affects 25 percent of babies born preterm,
usually before 32 weeks of pregnancy.
• Little brain bleeding usually leave no or few
complications, but severe bleeding often result
in brain damage or even death.
Neurodevelopmental problems have
been linked to lack of maternal
thyroid hormones, at a time when
their own thyroid is unable to meet
postnatal needs.
Children born preterm are more likely to have
white matter brain abnormalities early on causing
higher risks of cognitive dysfunction.
White matter connectivity between the frontal and
posterior brain region is critical in learning to
identify patterns in language.
. Preterm children are at a greater risk for having
poor connectivity between these areas leading to
learning disabilities.
Neurological problems include:
apnoea of prematurity
hypoxic-ischemic encephalopathy ,
retinopathy of prematurity ,
developmental disability,
cerebral palsy.
•Cardiovascular complications may arise from the
failure of the ductus arteriosus to close after birth:
patent ductus arteriosus.
Gastrointestinal and metabolic
problems can arise from
hypoglycemia, feeding difficulties,
rickets of prematurity, hypocalcemia,
inguinal hernia, and necrotizing
enterocolitis
Hematologic complications include
anemia of prematurity,
thrombocytopenia, and
hyperbilirubinemia that can lead to
kernicterus.
Infection, including sepsis,
pneumonia, and UTI.
Management of Preterm Labour:
Goals of obstetric patient management of preterm
labour should include:
(1) Early identification of risk factors associated with
preterm birth.
(2) Timely diagnosis of preterm labour.
(3) Identifying the aetiology of
preterm labour.
(4) Evaluating foetal well-being.
(5) Providing prophylactic therapy to
prolong gestation and reduce the
incidence of RDS and intra-amniotic
infection (IAI).
(6) Initiating tocolytic therapy when indicated.
(7) Establishing a plan of maternal and foetal
surveillance to improve neonatal outcome .
Diagnosis:
History: Symptoms include:
•Regular contractions
—
Contractions of sufficient frequency
and intensity to effect progressive effacement and dilation of the
cervix at 24-37 weeks’ gestation .
• a tightening sensation in the abdomen.
.
Constant low, dull backache.
•Mild abdominal cramps.
•Vaginal spotting or bleeding.
•Watery vaginal discharge in a gush or a trickle.
•A change in vaginal discharge.
.
Risk factors.
PHYSICAL EXAM:
Vital signs: PR, RR, Temp., Bp.
Chest and CVS exam,
Abdominal exam.
For uterus size, uterine contractions, the lie and
presenting part with foetal heart rate.
Pelvic exam .; for signs of labour.
and for presence or absence of signs of genital tract
infection
.
INVESTIGATIONS Specific for PTL:
Fetal fibronectin:
It is glycoprotein secreted by chorionic cells.
It’s presence in the cervical or vaginal
secretions indicates that the border between
the chorion and deciduas has been disrupted.
A positive test between 20- 36 weeks
indicates an increased risk of preterm birth.
It is normally positive before 20 weeks of
gestation and after 36 weeks of gestation
Negative between 20 -36 weeks of gestation.
If the diagnosis of preterm labour is suspected, but
not confirmed, it may be first obtain a vaginal
foetal fibronectin sample before pelvic cervical
examination.
If the diagnosis remains in doubt after the exam,
the specimen can be sent to the lab for analysis.
Ultrasound :
For cervical length& obstetric U/S.
At 24 weeks gestation a cervix length
of less than 25 mm defines a risk
group for preterm birth.
the shorter the cervix the greater the
risk.
In women with preterm contractions,
cervical length exceeds 30 mm are
unlikely to deliver within the next
week.
Evaluate for the presence of genital tract
infection:
Tocolytics are contraindicated in the presence of
symptomatic intra amniotic infection.
The definition of intra amniotic infection (ie,
chorioamnionitis) includes a temperature greater than
38.0°C (100.0°F) and 2 of the 5 following signs:
•WBC count greater than 15,000 cells/mm
3
•Maternal tachycardia greater than 100 beats per
minute .
•Foetal tachycardia greater than 160 bpm.
•Tender uterus
•Foul-smelling discharge
TREATMENT:
Admission to hospital with intensive neonatal care.
Options of treatment.
A. Delivery.
B. Conservative treatment.
A- Delivery:
INDICATIONS to continue the labour:
Advanced labour cervical dilatation
more than 3 cm and fully effaced
cervix.
Premature rupture of membranes and
uterine contractions.
There is ante partum haemorrhage.
There is chorio- amnionitis .
Foetal compromise.
Congenital malformation and foetal
death.
Severe pre- eclampsia.
Management during Labour:
First Stage, Second Stage& Third Stage:
No indication to use oxytocin.
No need for artificial rupture membrane.
Avoid frequent pelvic exam.
Not use narcotic drug to relief labour pain.
If need instrumental delivery use forceps
than ventose before34 weeks.
Active management of Third Stage due to
increase risk of PPH.
Indications of Operative delivery;
B- To stop uterine contractions using:
Tocolytic Drugs:
Medications that been used to stop uterine
contractions.
It’s also use In the management of intra
partum foetal distress and impaired foetal
growth and to facilitate external cephalic
version at term.
- Aimed at preventing the onset of preterm labour, for
women at risk of preterm birth.
- Interventions to improve outcome for foetuses at risk
of being born preterm
,
as those needing transfer to a
hospital which can provide neonatal intensive care.
- Use for time to let action of antenatal corticosteroids
in
those who have not yet completed a full course of
corticosteroids
and magnesium sulphate for
neuroprotection.
It’s Action: The concentration of calcium in the
myometrial cell dictates the degree of contractility.
- Levels of intracellular calcium and calcium
flux are regulated by a variety of mechanisms, it
rises either because calcium enters the cell from
outside through voltage gated calcium channels, or
because it is released from the sarcoplasmic reticulum.
Tocolytics exert their effect by reducing the level of
intracellular calcium.
Use them associated with a prolongation of pregnancy
for up to 7 days but with no significant effect on
preterm birth and no clear effect on prenatal or
neonatal morbidity.
Tocolysis should not be used where there is a
contraindication to prolonging pregnancy.
Using multiple tocolytic drugs associated with a higher
risk of adverse effects and so should be avoided.
When using a tocolytic drug, the best choice is the most
effective with the fewest adverse effects, both
immediate and long-term.
CALCIUM CHANNEL BLOCKERS:
There are two types of calcium channels in the
myometrial cell, the L type and the T-type.
Nifedipine binds to the inside of myometrial L-type
voltage dependent calcium channels causing them to
remain closed, and so inhibits contractility.
However, these L type channels are present in other
types of smooth muscle cells such as vascular smooth
muscle.
The T type calcium channel is peculiar to
myometrium.
Calcium channel blockers were associated with:
Less neonatal respiratory distress syndrome;
Less necrotising entero colitis ;
and less intraventricular haemorrhage than other
tocolytic drugs.
Nifedipine, the most commonly used , crosses the
placenta,but whetherit has any long-term effect on
the foetus is uncertain.
Animal studies with very high doses have reported
abnormalities of foetal and placental blood flow and
abnormal digital development. No congenital defects
have been associated with its use in humans.
.The dose of nifedipine is an initial oral dose of 20 mg followed
by 10–20 mg three to four times daily, adjusted according to
uterine activity for up to 48 hours. A total dose above 60 mg
associated with a three- to four-fold increase in adverse events
such as headache and hypotension.
Nifedipine and atosiban have comparable effectiveness in
delaying birth for up to seven days.
Compared with beta-agonists, nifedipine is associated with
improvement in neonatal outcome.
Ritodrine and atosiban are licensed in the UK for the
treatment of threatened preterm labour ,while nifedipine
is an unlicensed for PTL, it has the advantages of oral
administration and a low purchase.
Cyclo-oxygenase (COX) inhibitors:
Cyclo-oxygenase enzymes contribute to production of
prostaglandins, which are important in the onset and
maintenance of labour so inhibitors of the inducible
COX-2 enzyme might be effective tocolytics .
Indomethacin is used for tocolysis.
COX inhibitors cross the placenta and potential adverse
effects for the foetus include premature closure of the
ductus arteriosus with consequent pulmonary
hypertension, persistent patent ductus arteriosus,
necrotising entero-colitis and intra-ventricular
haemorrhage.
Magnesium sulphate:
There is no clear evidence that magnesium sulphate
reduces the risk of preterm birth but it’s administration
in preterm labour as neuroprotection& reduces the risk
of cerebral palsy . It should be received for 24 hours to
reduce this.
Cerebral palsy risk in preterm is seven fold than in term
baby.
Beta-agonists: (ritoridine ,salbutamol)
They have a high frequency of adverse
effects.
Nifedipine, atosiban and the COX
inhibitors have fewer types of adverse
effects, and they occur less frequently
than for beta-agonists
.All beta-agonists, have unpleasant or
potentially life threatening adverse effects for the
woman better use a safer alternative.
Adverse effects, include palpitations, tremor,
nausea or vomiting, headache, chest pain and
dyspnoea
.
Rare but serious complication of beta agonists
there are case reports of a small number of
maternal deaths associated with use them.
Pulmonary oedema is another complication
.
PROGESTERONE:
It is present in high concentrations during
pregnancy, increases cAMP production. cAMP and
cGMP maintain uterine quiescence by promoting
the uptake of intracellular calcium into the
sarcoplasmic reticulum and thereby reducing
intracellular calcium concentrations and reducing
contractility. They also lower the amount of
phosphorylated myosin and promote myometrial
relaxation.
Atosiban:
It is anti- oxytocin ,
suggested dose of atosiban of
an initial bolus dose of 6.75 mg over 1 minute,
followed by an infusion of 18 mg/hour for 3
hours, then 6 mg/hour for up to 45 hours (to a
maximum of 330 mg).
In multiple pregnancy whether or not tocolysis
leads to any benefit in preterm labour,
although
both nifedipine and atosiban have been widely
used .
Prevention:
We might not be able to prevent preterm labour , but
there's much we can do to promote such as:
•Regular prenatal care; can help in monitoring maternal
and foetal wellbeing.
•Diet: more folic acid, calcium, iron.
•Gain weight: Gaining the right amount of weight can
support foetal health.
• A weight gain of 25 to 35 pounds (about 11 to 16
kilograms) is recommended.
•Avoid risky substances; quit smoking. It might trigger
preterm labour. Alcohol and illicit drugs are off-limits
Pregnancy spacing:
Some researches suggest a link between
pregnancies spaced less than six months apart and
an increased risk of premature birth.
.
When using assisted reproductive technology:
Multiple pregnancies carry a higher risk of preterm
labour.
Taking medications:
Treatment with a vaginal progesterone gel during
the second and third trimesters might decrease the
risk of preterm birth in women who have short
cervixes.
•Sexual activity: If the patient had a history of
preterm labour or experience signs or symptoms of
preterm labour, she might need to restrict sexual
activity
•Regarding physical activities:
Avoiding heavy lifting.
Managing chronic conditions:
Certain conditions, such as diabetes and high
blood pressure, increase the risk of preterm labour;
control them before conception.
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