Prematurity and Twins Max Brinsmead MB BS Ph

Prematurity and Twins Max Brinsmead MB BS Ph. D December 2015

Pre term Birth 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

When confronted by possible Preterm Birth There are 6 questions you need to ask yourself And they need to be answered ASAP Because time is of the essence

6 Questions about 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?

Is this baby premature? 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 it Labour? 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

Fetal Fibronectin 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 specificity Overall ~50% But this can be improved by using the quantified bedside test

Ultrasound Measures of Cervical Length 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

Why is Labour occurring Now? Underlying maternal problem? Is the baby normal? Antepartum haemorrhage Chorioamnionitis Ruptured membranes Cervical incompetence

Should Labour be Suppressed? Is the baby better off in or out? Will depend on your local resources At the limits of viability (22 – 25 w) survival with handicap is possibly the worse outcome So you need to be aware of the wishes and resources of the family

Can the Labour be Suppressed? In many cases the answer is YES But Advanced labour and ruptured membranes sometimes make it difficult

What is the best tocolytic to Use? 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 32 w

Overall, uterine tocolysis: 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

What else can be done for the patient in premature labour? Psychological care Administration of steroids Doubles survival and halves all complications Can the patient be transferred? Doubles survival and halves handicap Mg. SO 4 to prevent brain damage When to use antibiotics

Corticosteroids 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 26 w – 40 w Effective for all clinical indications including: Idiopathic pre term labour PROM Maternal hypertensive diseases Twins (maybe)

Corticosteroids (2) 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

Mg suphate for Neuroprotection 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

Infection and Prematurity 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?

Optimal Intrapartum Care for the Premature Fetus 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?

Prediction and Prevention of Preterm Birth 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

Progestational Agents NEJM June 2003 A DB PC RCT of weekly injections of 17 hydroxyprogesterone caproate from 16 -20 w in 267 high risk women in several centres Reduced delivery at <37 w from 55% to 36% Reduced delivery at <32 w from 20% to 11% These results confirmed by a meta analysis that includes previous trials AND They have now proven effective in a wide range of patients at risk incl. twins The best agent to use is vaginal Progesterone

Multiple Pregnancy

Incidence 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)

Twin Problems 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

But the single most important predictor of Risk in a twin pregnancy is Is. Chorionicity

Types of 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

Early Diagnosis is Important The early diagnosis of twins is one of the reasons to advocate universal 1 st 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

Monochorionic Twins 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 2 nd trimester

Management of Twin Pregnancy Patient counselling Issues of prenatal diagnosis Nutrition and rest More frequent AN visits Dealing with the discomforts of pregnancy

Management of Twins – Delivery & Beyond 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

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