Twin Pregnancy: What Nobody Tells You in the First Trimester
By Jennifer James, UK twin mum and author of Outnumbered From Day One, the honest guide to life with twins.
Finding out you're expecting twins tends to produce two things simultaneously: a rush of feeling, and an immediate, urgent need for information. This post is for the second one.
The first trimester with twins looks different from a singleton pregnancy in a few important ways, and some of those differences are worth knowing about before your next appointment so you can ask the right questions rather than leaving and realising later what you forgot to ask.
Your first appointment will be different
A multiple pregnancy is considered higher risk than a singleton pregnancy, not because something is necessarily wrong, but because there are more variables to monitor. You should be referred to a specialist multiple pregnancy clinic or assigned a midwife with multiple pregnancy expertise. This is standard care, not a sign of a problem.
If this hasn't been mentioned after your initial scan confirms twins, ask. You're entitled to a clear explanation of your care pathway.
The chorionicity question
The most important thing to establish early is the chorionicity of your twins, which means whether they share a placenta or have separate placentas.
Identical twins can be monochorionic (sharing one placenta) or dichorionic (each with their own). All non-identical twins are dichorionic. This distinction matters because monochorionic twins require more frequent monitoring and carry a higher risk of a complication called Twin to Twin Transfusion Syndrome (TTTS), where blood flow between the twins becomes unequal.
Chorionicity is most accurately determined before 14 weeks, so if your first scan is early enough, this should be assessed and confirmed.
DCDA (dichorionic diamniotic): two placentas, two sacs. The most common type of twin pregnancy.
MCDA (monochorionic diamniotic): one placenta, two sacs. Most common type of identical twin pregnancy.
MCMA (monochorionic monoamniotic): one placenta, one sac. The rarest and highest-risk type.
Symptoms are more intense
This is not imagined. Twin pregnancy involves higher levels of hCG and progesterone than singleton pregnancy, which tends to mean more pronounced nausea, more fatigue, and a faster-growing bump. If your symptoms are severe, tell your midwife. Hyperemesis gravidarum (severe pregnancy sickness) is more common in multiple pregnancy and there are treatments available.
Fatigue in the first trimester with twins can be significant. Rest when you can and don't underestimate it.
The fatigue eases for most people by the second trimester, but the first weeks at home with two newborns bring their own version of it. What to expect for twin sleep in the first six months is worth a read before you're in it.
How many scans will you have?
More than a singleton pregnancy. The exact number depends on your chorionicity and any complications, but as a baseline, DCDA twins are monitored with scans every four weeks from 20 weeks. MCDA twins are scanned every two weeks from 16 weeks due to the higher monitoring requirement.
In the first trimester, you'll have your dating scan and the chorionicity assessment. You may also be offered a combined screening test (nuchal translucency, PAPP-A, and hCG) for chromosomal conditions. This works slightly differently with twins and your sonographer will explain the implications.
What to ask at your first appointment
Write these down and take them with you:
What type of twins are they (chorionicity)? What does my care pathway look like? Who is my point of contact if I have concerns? What symptoms should prompt me to call? When is my next scan? Will I be seen by a consultant as well as a midwife? Is there a specialist multiple pregnancy midwife at this hospital?
You are allowed to ask all of these. They are not unreasonable questions.
A word on information overload
The internet contains a significant amount of twin pregnancy content, some of it extremely alarming. Complications exist and are worth knowing about, but the majority of twin pregnancies result in healthy babies delivered by a team who has done this many times before. Read about what's relevant to your specific type of twin pregnancy. Try not to read every worst-case scenario for every type simultaneously.
If you want this kind of UK-specific, honest information in one place rather than scattered across blog posts, the first three chapters of Outnumbered From Day One cover pregnancy from the first scan through to birth. You can download a free sample to read before you commit.
If you're starting to think about practical preparation, the twin baby equipment guide by stage is the next thing worth reading.
FAQ
What are the first signs of twin pregnancy? More pronounced nausea, extreme fatigue, and a faster-growing bump are common in twin pregnancy, partly due to higher hormone levels. Some people have no unusual symptoms at all in early pregnancy. A scan is the only way to confirm twins.
What is the difference between DCDA and MCDA twins? DCDA twins each have their own placenta and sac. MCDA twins share a placenta but have separate sacs. MCDA twins require more frequent monitoring due to a higher risk of Twin to Twin Transfusion Syndrome.
How many scans do you get with twins in the UK? More than a singleton pregnancy. DCDA twins are typically scanned every four weeks from 20 weeks. MCDA twins every two weeks from 16 weeks. Exact numbers depend on your hospital and any complications.
When is chorionicity determined? Most accurately before 14 weeks. This is one reason early scanning matters in twin pregnancy.