They say that having twins is ‘double the trouble and twice the joy'. It’s completely understandable that known risks associated with a twin pregnancy can cause some anxiety, however, with the right support and guidance from a highly-experienced obstetrician with specialist interests in maternal and fetal medicine, you can stay healthy, protect your growing babies, and be well-prepared for birth and beyond.
Is there an increased risk with a twin pregnancy?
Yes, a twin pregnancy is associated with increased risk for both Mum and Babies. The risk of maternal mortality is 2.5 times higher in multiple births than in singleton births, and the chances of an earlier delivery is also significantly higher in a twin pregnancy, which means your babies may need additional support immediately post-birth.
The good news is that we now have more experience of caring for twin pregnancies, due to their higher incidence in light of an increase in average maternal age and associated use of assisted fertility treatments; multiple births now account for 3% of all live births. Choosing an experienced obstetrician who can provide regular monitoring and continuity of care is therefore the very best first step towards a healthy twin pregnancy, a safe delivery, and a great start to new and happy lives together.
What are the signs I am having twins?
Women who are pregnant with twins often notice that the line on their positive pregnancy test is darker and more distinct at an earlier stage. This is because levels of the pregnancy hormone hCG (human chorionic gonadotropin) are usually elevated in multiple pregnancies. These higher levels can also be detected on hCG blood tests. Some of the effects of this may be that you feel particularly tired and drained, and suffer badly with morning sickness. A bigger than average bump may also be a clue that there could be more than one baby developing inside your womb. In truth, not all women with a twin pregnancy will have the same response to the hormonal changes, and you may have none of these signs despite being pregnant with twins. The one way to know for sure if you’re pregnant with twins is with your first ultrasound scan, at around 6/7 weeks, when two tiny heartbeats may be visible.
Types of twins
You should be carefully scanned by a fetal medicine specialist between 11 and 14 weeks so the ‘chorionicity’ and the ‘amnionicity’ of your twin pregnancy can be determined. The chorionicity refers to the placenta, and whether you babies have their own (as in a dichorionic twin pregnancy) or are sharing a placenta (as in a monochorionic twin pregnancy). The amnionicity refers to the amniotic sac, and describes whether your babies are in their own sacs (diamniotic) or share a sac (monoamniotic).
If your babies each have their own placenta and own amniotic sac, then you have a DCDA twin pregnancy, a dichorionic diamniotic twin pregnancy.
If your babies are sharing one placenta with two sacs, then you have an MCDA twin pregnancy – a monochorionic diamniotic twin pregnancy.
MCMA twins are more rare where the babies share the same sac and the same placenta.
Why does twin type matter?
The importance of twin typing goes well beyond whether your two babies are going to look alike. The information helps Dr Duncan to know the risk of complications developing, and this in turn informs the best plan for managing your pregnancy, based on evidence and experience. MCDA twin pregnancies are more complicated than DCDA and tend to have increased risk of transfusion between twins, growth restriction, and congenital abnormalities, and need extra care and closer monitoring throughout pregnancy.
Fraternal (dizygotic) twins
Fraternal or non-identical twins are the most common type of multifetal pregnancy. It happens when two separate eggs are fertilised by two separate sperm cells (thus creating two separate zygotes, hence dizygotic). This means that fraternal twins are like any other pair of siblings; they may share a birthday, but they do not have exactly the same genetic make-up. They therefore do not look identical and can be different sexes. If you’re wondering how two eggs can be available for fertilisation at the same time, you’re not alone. Many shell-shocked parents have asked precisely the same question. The truth is, there are lots of different reasons. Researchers suggest that some mothers may be genetically prone to releasing lots of eggs instead of just the one, and this type of twin does tend to run in families. It can also be more likely to occur in older mums or with the use of some fertility drugs, such as clomid, which stimulates follicular development.
Identical (monozygotic) twins
Identical twins occur when one zygote (one egg having been fertilised by one sperm) splits in two, thus producing two identical embryos.
Monozygotic twins, sharing the same genetic material, are the same sex and generally look exactly the same, or thereabouts. I say thereabouts, because although their DNA is essentially identical, environmental factors can have a significant influence on genes. They can be turned on and off in a phenomenon known as epigenetic modification. Even in identical twins there will be ways of telling the difference, and as someone who has delivered many twins I am intrigued by how two individuals with the same DNA can be so different, both physically and emotionally.
Monozygotic twinning can occur spontaneously after natural conception or after IVF treatment. It is not fully understood why a zygote may divide into two, producing identical twins. The later in pregnancy that this division occurs, the more structures that will be shared. These two ‘blastocysts’ can both implant in the lining of the uterus to form two identical embryos. Even after years of studying, researching and delivering twins, it’s still a process that fills me with awe.
Chorionicity
The chorionicity of twins relates to whether they share the same placenta and lining of the fluid sac, and is dependent on precisely when the zygote divides:
- Dichorionic/diamniotic: These twins divide at the earliest stage and so each twin has their own placenta as well as their own chorion and amniotic sac
- Monochorionic/diamniotic: The zygote forming these twins, will usually divide between four and eight days after fertilisation. These identical twins share a placenta and chorionic sac but have their own amniotic sac.
- Monochorionic/monoamniotic: These twins develop from a zygote that splits late, usually between eight and twelve days after conception. The twins will share a placenta, chorionic and amniotic sac. If the division occurs more than twelve days after fertilisation, the twins will share even more and are likely to be conjoined and share body parts.
Dr Duncan would be delighted to look after you during your twin pregnancy, please get in touch with the clinic to book your appointment.
Twin Pregnancy FAQs
Twins can be the result of a variety of causes. They can arise naturally due to the release of multiple eggs or multiple ovulations, or the splitting of a single fertilised egg, or by medical intervention via fertility treatments such as IVF, when multiple embryos are placed in the womb. The particular way in which twins are conceived determines the degree of relatedness between them, as well as whether they’re identical or not.
If you’re pregnant with more than one baby, it’s especially important to look after your own health and wellbeing. A balanced diet which includes plenty of fruit, vegetables, fish, lean meat and eggs, pulses, dairy and wholegrains will nourish your body and the babies growing inside you. Exercise will keep you fit and ready for the challenges ahead, and together with quitting alcohol, will ensure you give your babies the best start to life.
You’re more at risk of developing iron deficiency anaemia during a multiple pregnancy. You can boost your body’s iron levels with red meat, fortified cereals and plenty of leafy green vegetables, washed down with a glass of orange juice, as the vitamin C in the juice will help your body absorb the iron in the food.
Yes. A multiple pregnancy can be wonderful, but it can also be utterly exhausting. It is important to be gentle with yourself. Take regular rest, make sure you get enough sleep, and if you’re feeling stressed, you should seek to minimise this before you feel overwhelmed. Having a solid support system in place, including friends, family and medical professionals, is of paramount importance.
Morning sickness and indigestion can be a real problem, and this can often be managed by eating little and often. If however you need additional help, then anti-sickness and/or anti-acid medications can be prescribed.
The size of your bump, the demands of your growing babies, and a hormonal surge can mean that a multiple pregnancy can bring more pronounced problems alongside pregnancy’s usual niggles and gripes:
- The weight of your babies can press on your pelvic blood vessels, increasing the risk of varicose veins and haemorrhoids. You can stay comfortable by wearing support tights and by putting your legs up when you have a quiet moment. Taking plenty of fluids and fibre will keep you regular and prevent painful constipation.
- Your expanding bump, together with pregnancy hormones that soften and stretch your ligaments, means you may be plagued by backache or pelvic pain. Whatever problems you may experience though, I urge you not to suffer in silence. Please speak to me and I can refer you to a specialist physiotherapist or chiropractor for treatment and advice.
Antenatal appointments are important in any pregnancy, but they’re especially important if you’re carrying twins. Dr Duncan will want to keep a close eye on you and your babies.
If you have a multiple pregnancy, you are at increased risk of high blood pressure, gestational diabetes and preterm delivery, however with close monitoring, early detection and treatment of any problems as they emerge, we should be able to keep you and your babies as healthy as possible.
We will talk through the risks, signs and symptoms of pre-term labour, and by 32 weeks we will expand this discussion to agree on the timing of birth and the possible mode of delivery. Together we can develop the best birth plan for you and your precious babies.