Prematurity and Twins

Max Brinsmead MB BS PhDMarch 2014

Affects 8-15% of our obstetric patients

Increasing in frequency

Contributes significantly to perinatal mortality and morbidity

Is a particular challenge to those who work with limited neonatal facilities

Pre term Birth

There are 6 questions you need to ask yourself

And they need to be answered ASAP

Because time is of the essence

When confronted by possible Preterm Birth

1 Is the baby premature? 2 Is it really labour? 3 Why is labour occurring now? 4 Should the labour be suppressed? 5 Can the labour be suppressed? 6 What else can be done?

6 Questions about Preterm Birth

Dates uncertain or unknown?

Be the obstetric detective!

The earliest ultrasound is best

Measure uterine size and estimate fetal weight But there is a problem with PROM!

Use USS to measure biparietal diameter & femur length

Remember the baby that is mature before its time

Is this baby premature?

Listen to what the patient is telling you

Has it happened before?

A warm hand is better than a tocograph!

Ruptured membranes - if it isn’t obvious then it isn’t relevant

Cervical assessment

Observation over time

Is it Labour?

A fetal connective tissue protein

Released into the cervix and upper vagina

A bedside immunoassay test

High negative predictive value of delivery within seven (7) days (particularly in women who present with contractions)

Poor positive predictive value and sensitivity Overall ~50%

(Based on a 2003 BMJ meta analysis of 40 published studies)

Fetal Fibronectin

Simple and safe

Expertise and equipment required

High negative predictive value if the cervix is >15 mm and there is no beaking of membranes with straining down

The positive predictive value and sensitivity is less certain

The appropriate intervention for a short cervix is also debatable

Ultrasound Measures of Cervical Length

Underlying maternal problem?

Is the baby normal?

Antepartum haemorrhage

Chorioamnionitis

Ruptured membranes

Cervical incompetence

Why is Labour occurring Now?

Is the baby better off in or out?

Will depend on your local resources

At the limits of viability (22 – 25w) survival with handicap is possibly the worse outcome

So you need to be aware of the wishes and resources of the family

Should Labour be Suppressed?

In many cases the answer is YES

But

Advanced labour and ruptured membranes sometimes make it difficult

Can the Labour be Suppressed?

I prefer IV Betamimetics Ventolin by infusion until MPR >110 but <140 bpm. Rapidly

effective but maternal side effects common

Oral Nifedipine has fewer side effects RCT comparisons with betamimetics suggest improved neonatal

outcomes

Atobisan = an oxytocin blocker As effective as Ca channel blocker in delaying delivery Questions arising from long term follow up of children Not used in Australia

Gyceryl trinitrate - transdermal patch Not commonly used

NSAIDs Problems include premature closure ductus and renal effects Rebound effects described after withdrawal at 32w

What is the best tocolytic to Use?

Prolongs gestation But the gains are modest

Buys time for perinatal transfer and administration of steroids

By themselves they have no effect on perinatal mortality and morbidity

Ineffective or impractical for long term use

Overall, uterine tocolysis:

Psychological care

Administration of steroids Doubles survival and halves all complications

Can the patient be transferred? Doubles survival and halves handicap

MgSO4 to prevent brain damage

When to use antibiotics

What else can be done for the patient in

premature labour?

Effectively reduce the risk of: Hyaline membrane disease Necrotising enterocolitis Intracranial haemorrhage Death and disability

Are safe in the short and long term Are effective at gestations 26w – 40w Effective for all clinical indications

including: Idiopathic pre term labour PROM Maternal hypertensive diseases Twins (maybe)

Corticosteroids

Must be given within 24 hrs and 7 days

Repeat once if <34 weeks or still high risk

Optimum formulation, dose & route – uncertain

I prefer IM Betamethasone

Corticosteroids (2)

Effectively reduces the risk of: Periventricular leucomalacia Cerebral palsy Overall OR is 0.14 (CI 0.05 – 0.51)

Recommended for gestations <30 weeks

Must be given within 24 hrs of birth

Consider repeating if <30 weeks and >24 hrs

Dose is the same as that used for Eclampsia

Mg suphate for Neuroprotection

Subclinical infection implicated in 40-70% of pre term labour

Also has a sinister role in the aetiology of cerebral palsy

The results of therapeutic trials of antibiotics in preventing pre term birth are confusing

Vaginosis is a risk factor for prematurity But screening and treatment should be reserved for those at risk Most studies have focused on anaerobic BV

Erythromycin or Clindamycin is useful after PROM Best not to give antibiotics for idiopathic

premature labour with intact membranes Perhaps the source of infection is outside the

genital tract?

Infection and Prematurity

Delivery at the optimal site the most important

Avoid hypoxia and trauma

Avoid sedatives and narcotics if possible

CS for the pre term breech?

CS for the very premature?

Optimal Intrapartum Care for the Premature Fetus

Prior history of preterm birth the best predictor

But also look out for overworked, stressed, abused and smoking patient

And those with other chronic diseases Multiple pregnancy The short & incompetent cervix is a continuum

Monitor and plot on a scale against GA Consider suture for cervix <15 mm Vaginal progesterone gaining acceptance as the most

valuable agent to use

Prediction and Prevention of Preterm

Birth

NEJM June 2003 A DB PC RCT of weekly injections of

17hydroxyprogesterone caproate from 16-20w in 267 high risk women in several centres

Reduced delivery at <37w from 55% to 36% Reduced delivery at <32w from 20% to 11%

These results confirmed by a meta analysis that includes previous trials

ANDThey have now proven effective in a wide

range of patients at risk incl. twins

The best agent to use is vaginal Progesterone

Progestational Agents

Multiple Pregnancy

Twins 1:80 in Caucasians Assisted conception (IVF) explains

most of the increasing incidence But incidence is also affected by:

Race (1:50 Black Africans, 1:150 in Asians) Family history (mean FSH levels) Older maternal age Increasing parity

Spontaneous triplets 1:6400 (Hellin’s Law)

Incidence

Prematurity Risk of pre term delivery twins increased 5-fold And 10-fold for triplets 14% twins and 41% triplets born very pre-term

Intrauterine growth restriction Often manifest as discordant growth

Congenital malformations increased 2-fold In monochorionic twins only

Increased rate of maternal pregnancy disorders

e.g. Pre eclampsia, gest. Diabetes, APH etc

Overall PN mortality increased 2 – 3-fold

Twin Problems

isIsChorionicity

But the single most important predictor of Risk in a twin

pregnancy

Dizygotic – arise from two eggs. These are non-identical twins

Monozygotic – one egg or embryo that splits These are identical twins (clones)

But from a clinical perspective it is chorionicity that is important

Dichorionic (two chorion, separate sacs and placentas) Monochorionic (one chorion and a shared placenta)

Monochorionic and diamniotic (separate sacs) Monochorionic and monamniotic (only 1%)

About 1/3 twin pregnancies are monochorionic

Types of twin pregnancy

The early diagnosis of twins is one of the reasons to advocate universal 1st trimester scans

AND It is the best time to document

chorionicity By looking for and studying the gestational sac(s) “Y” sign = dichorionic “T” sign = monochorionic

Early Diagnosis is Important

Almost all share vessels in their common placenta

But for 10 – 15% unidirectional flow results in twin-to-twin transfusion (TTS) which can:

Cause discordant growth Has cardiovascular , haematological and amniotic fluid

burdens Result in the death of one twin And a high risk of neurological damage to the survivor

MC and MA twins Are at high risk of cord entanglement Or succumb to acute polyhydramnios in the 2nd trimester

Monochorionic Twins

Patient counselling

Issues of prenatal diagnosis

Nutrition and rest

More frequent AN visits

Dealing with the discomforts of pregnancy

Management of Twin Pregnancy

Monitoring fetal growth and well being A role for regular ultrasound with Doppler flow

studies Place of Delivery Time of delivery Intrapartum fetal monitoring Method of delivery Issues of lactation Two for the price of one or twice as hard? A role for Support Groups

Management of Twins – Delivery & Beyond

Any Questions or Comments?

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