What is the importance of ultrasound for multiple pregnancies?
Congratulations – you’re pregnant! Carrying twins or other multiple pregnancies has implications for both you and your babies. Because you are having two pregnancies at once, there is an increased chance of pre-term labour, growth and structural problems and it is important that both or all babies are assessed carefully and in detail.
Ultrasound Care’s obstetricians recommend an initial dating ultrasound is performed and at that time, we can determine if you have a multiple pregnancy.
What are the different types of twin pregnancies?
Each pregnancy sac has two membrane layers, the amnion is the layer in the inside of the sac, closest to the babies. The chorion is the outside layer. Some twins each have their own amnion and chorion, other twins share one or two of the membrane layers.
The types of twins influence their risks and monitoring. It is therefore crucial that the number of chorions present is determined. This is best done by ultrasound prior to 14 weeks. This can be done at a dating scan or the 11-14 week scan.
The most common types of twins are dichorionic diamniotic, where each twin has its own amnion and chorion. Each twin will have its own placenta. The next most common is diamniotic monochorionic. In this case, the twins share a chorion and placenta but have their own individual amniotic sacs. Twins can also share both a chorion and amnion layer or be joined together.
What are the implications of a multiple pregnancy?
Carrying twins has implications for both you and your babies. You may feel more nauseous, have a higher chance of becoming anaemic and of developing issues with blood pressure and diabetes in pregnancy. As mentioned in the opening paragraph of this article, as you are having two pregnancies at once, there is also an increased chance of pre-term labour, growth and structural problems, so it is important that both or all babies are assessed carefully and in detail.
Remember, each of these scans will take twice the amount of time, as we need to look at both babies. When you book your scans, once we have identified a multiple pregnancy, we ask you to remind our admin team that you are having twins each time you book so that we can ensure we give you all the time you and your babies need for your scan. Your health, and your babies’ health is important to us, and that takes time to assess. Please allow plenty of time for your scans and don’t forget to let our care team know if you need a break during the scan.
Types of Twins
Each baby has its own amnion and chorionic membranes. In this case the placentas are not connected, even though they may lie close to each other. The gender of the babies may be the same or different. 15% of these types of twins will still be identical.
The additional scans that are recommended by Ultrasound Care’s clinicians are:
- A dating scan. This is important to ensure that each pregnancy sac has both a chorion and an amnion layer and that nothing is shared.
- An ultrasound at 11-14 weeks is recommended to assess each of the baby’s early anatomy and nuchal translucency, (if you consent).
- At 18-20 weeks, a fetal morphology scan is performed.
- Regular ultrasound scans to monitor the babies’ growth and well-being usually performed at 28 and 34 weeks gestation.
- More frequent scans may be required if any medical concerns arise during your pregnancy and your Ultrasound Care clinician or sonographer will discuss these with you.
What is the recommended ultrasound scan program for a multiple pregnancy?
If you have a multiple pregnancy, it is important to have ultrasounds performed at key timelines to ensure your health and the health of your babies is monitored.
Ultrasound Care’s specialist clinicians and sonographers will be able to guide you and provide advice throughout your pregnancy as to what scans are recommended to help ensure the ongoing good health of you, and your babies. Please call us and advise if you have a multiple pregnancy and we will be able to assist you.