management and timing of birth
Last reviewed 01/2018
- early diagnosis is essential
- supplementation of iron and folic acid
- regular monitoring of haemoglobin levels
- increased level of review in antenatal clinic
- booking of the birth into a specialist unit
NICE have given guidance regarding the diagnosis and assessment of multiple pregnancies (1)
Determining gestational age and chorionicity
- offer women with twin and triplet pregnancies a first trimester ultrasound
scan when crown-rump length measures from 45 mm to 84 mm (at approximately
11 weeks 0 days to 13 weeks 6 days) to estimate gestational age, determine
chorionicity and screen for Down's syndrome (ideally, these should all be
performed at the same scan)
- determine chorionicity at the time of detecting twin and triplet pregnancies
by ultrasound using the number of placental masses, the lambda or T-sign and
membrane thickness
- assign nomenclature to babies (for example, upper and lower, or left and
right) in twin and triplet pregnancies and document this clearly in the woman's
notes to ensure consistency throughout pregnancy
- use the largest baby to estimate gestational age in twin and triplet pregnancies to avoid the risk of estimating it from a baby with early growth pathology.
Monitoring for intrauterine growth restriction
- estimate fetal weight discordance using two or more biometric parameters
at each ultrasound scan from 20 weeks
- aim to undertake scans at intervals of less than 28 days
- consider a 25% or greater difference in size between twins or triplets as a clinically important indicator of intrauterine growth restriction and offer referral to a tertiary level fetal medicine centre
Screening for structural abnormalities
- offer screening for structural abnormalities (such as cardiac abnormalities) in twin and triplet pregnancies as in routine antenatal care
- consider scheduling ultrasound scans in twin and triplet pregnancies at a slightly later gestational age than in singleton pregnancies and be aware that the scans will take longer to perform
- allow 45 minutes for the anomaly scan in twin and triplet pregnancies
- allow 30 minutes for growth scans in twin and triplet pregnancies.
Monitoring for feto-fetal transfusion syndrome
- monitoring for feto-fetal transfusion syndrome should not be undertakne in the first trimester
- start diagnostic monitoring with ultrasound for feto-fetal transfusion syndrome (including to identify membrane folding) from 16 weeks. Repeat monitoring fortnightly until 24 weeks
- carry out weekly monitoring of twin and triplet pregnancies with membrane folding or other possible early signs of feto-fetal transfusion syndrome (specifically, pregnancies with intertwin membrane infolding and amniotic fluid discordance) to allow time to intervene if needed
NICE have issued guidance regarding the timing of birth if multiple pregnancy (1):
- discuss with women with twin and triplet pregnancies the timing of birth
and possible modes of delivery early in the third trimester
- inform women with twin pregnancies that about 60% of twin pregnancies result
in spontaneous birth before 37 weeks 0 days
- inform women with triplet pregnancies that about 75% of triplet pregnancies
result in spontaneous birth before 35 weeks 0 days
- inform women with twin and triplet pregnancies that spontaneous preterm
birth and elective preterm birth are associated with an increased risk of
admission to a special care baby unit
- inform women with uncomplicated monochorionic twin pregnancies that elective
birth from 36 weeks 0 days does not appear to be associated with an increased
risk of serious adverse outcomes, and that continuing uncomplicated twin pregnancies
beyond 38 weeks 0 days increases the risk of fetal death
- inform women with uncomplicated dichorionic twin pregnancies that elective
birth from 37 weeks 0 days does not appear to be associated with an increased
risk of serious adverse outcomes, and that continuing uncomplicated twin pregnancies
beyond 38 weeks 0 days increases the risk of fetal death
- inform women with triplet pregnancies that continuing uncomplicated triplet
pregnancies beyond 36 weeks 0 days increases the risk of fetal death
- offer women with uncomplicated:
- monochorionic twin pregnancies elective birth from 36 weeks 0 days, after a course of antenatal corticosteroids has been offered
- dichorionic twin pregnancies elective birth from 37 weeks 0 days
- triplet pregnancies elective birth from 35 weeks 0 days, after a course
of antenatal corticosteroids has been offered
- for women who decline elective birth, offer weekly appointments with the specialist obstetrician. At each appointment offer an ultrasound scan, and perform weekly biophysical profile assessments and fortnightly fetal growth scans.
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