Multiple pregnancy: twin and triplet pregnancies

Structure

Evidence of local arrangements to ensure that women with a multiple pregnancy are monitored for fetal complications according to the chorionicity and amnionicity of their pregnancy.

Data source: Local data collection.

Process

a) The proportion of women with a monochorionic multiple pregnancy who receive diagnostic monitoring for feto-fetal transfusion syndrome using ultrasound from 16 weeks and every 14 days until birth.

Numerator – the number of women in the denominator who received diagnostic monitoring for feto-fetal transfusion syndrome using ultrasound from 16 weeks and every 14 days until birth.

Denominator – the number of women who had a monochorionic multiple pregnancy and a gestational age greater than 16 weeks.

Data source: Local data collection.

b) The proportion of women with a monochorionic multiple pregnancy who receive diagnostic monitoring for fetal weight discordance using 2 or more biometric parameters and amniotic fluid level assessment at each ultrasound scan from 16 weeks.

Numerator – the number of women in the denominator who received diagnostic monitoring for fetal weight discordance using 2 or more biometric parameters and amniotic fluid level assessment at each ultrasound scan from 16 weeks.

Denominator – the number of women with a monochorionic multiple pregnancy and a gestational age greater than 16 weeks.

Data source: Local data collection.

c) The proportion of women with a dichorionic twin or trichorionic triplet pregnancy who receive diagnostic monitoring for fetal weight discordance using 2 or more biometric parameters and amniotic fluid levels at each ultrasound scan from 24 weeks.

Numerator – the number of women in the denominator who received diagnostic monitoring for fetal weight discordance using 2 or more biometric parameters and amniotic fluid levels at each ultrasound scan from 24 weeks.

Denominator – the number of women with a dichorionic twin or trichorionic triplet pregnancy and a gestational age greater than 24 weeks.

Data source: Local data collection.

Multiple pregnancy

A multiple pregnancy is defined as a twin or triplet pregnancy. [Expert opinion]

Fetal growth restriction

A difference in size of 25% or more between twins or triplets, known as fetal weight discordance, and an estimated fetal weight of any of the babies below the 10th centile for gestational age are clinically significant indicators of fetal growth restriction. The number of scans women receive to monitor for fetal growth restriction is determined by the amnionicity and chorionicity of the pregnancy and should follow the recommended schedule of specialist antenatal appointments, as detailed in the NICE guideline on twin and triplet pregnancy. The schedule of specialist appointments is also shown as part of the multiple pregnancy antenatal care proforma and care pathways produced by Twins Trust. [Adapted from NICE's guideline on twin and triplet pregnancy, recommendation 1.4.23]

Fetal biometric parameters

Standard antenatal ultrasound measures to assess the growth and wellbeing of the fetus and monitor for fetal weight discordance, they include:

[Expert opinion]

Feto-fetal transfusion syndrome

Feto-fetal transfusion syndrome occurs when blood moves from one baby to another. The baby that loses the blood is called the donor and the baby receiving the blood is called the recipient. Feto-fetal transfusion syndrome is a complication of monochorionic multiple pregnancies arising from shared placental circulation. It is also referred to as twin-to-twin transfusion syndrome in twin pregnancies. [NICE's guideline on twin and triplet pregnancy, terms used in this guideline]