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A twin pregnancy can be exciting, but overwhelming at the same time. Even though there is a higher risk of complications, most twins often do well. Expecting multiples requires special care and preparation. 

We’ve rounded up some insights that can help expectant moms who are in this journey, with hopes that it will prepare them for the months to come. Let’s take a dive into what to expect in the next few months, and beyond. Here’s what you need to know.

Twin Fetal Development 

Multiple pregnancy occurs when you are expecting two or more babies at the same time.

A twin pregnancy can bear identical (monozygotic) or fraternal (dizygotic) twins. 

Identical twins result when a fertilised egg becomes an embryo and splits in two and develops two babies. They share the same genes, and they are always of the same sex. 

Identical twins can have their own separate placenta and pregnancy amniotic sac if they split early, share a placenta but be in different amniotic sacs if they split later or share one single placenta and amniotic sac if they split late (very uncommon). Very rarely, we see conjoined twins where they even share some organs e.g. heart, brain or gastrointestinal system. Since they are connected through some vital organs, it’s expected that they may face major complications. 

Fraternal twins result when two separate eggs get fertilised by 2 different sperm during the same pregnancy making two different embryos. They share some of their genes just like any other siblings hence fraternal twins can be of the same or different sexes. They always have their own individual placentas and amniotic sacs. 

Determining placental (chorionicity)  and amniotic sac number ( amnionicity) is crucial for twins in the early gestation as more complications occur with more sharing.

What causes twin pregnancies?

You’re probably wondering why some women end up with multiples, while others don’t. There are several predisposing factors behind this especially for fraternal twins.

  • Fertility Drugs

There are subfertility treatments that cause more than 1 egg to develop and ovulate, making it more likely that you conceive with twins or more.

  • In vitro fertilisation (IVF)

IVF can result in a multiple pregnancy if more than one fertilised embryo is transferred to the uterus and then develops into fraternal twins. In some uncommon cases, a single fertilised embryo may split into identical twins after transfer.

  • Age

Women over 35 are more likely to release two or more eggs during a single menstrual cycle than younger women. So, older women are more likely to become pregnant with multiples.

  • Genetics

Having identical twins has no genetic inheritance pattern. But, fraternal twins tend to run on the mother’s side of the family. A woman with a mother or sister who have had fraternal twins are about twice as likely to conceive fraternal twins themselves as there is a genetic predisposition for some women to ovulate more than one egg per cycle.

What are the signs that I might be pregnant with twins?

Most women who are expecting twins find that their pregnancy symptoms are quite noticeable and early. This includes tiredness, excessive morning sickness, mood swings, nausea, vomiting, and constipation. There are also reports of early or frequent fetal movement. 

Compared to a single pregnancy, body changes with a twin pregnancy are much more obvious. Twin pregnancy may cause you to gain 16-20 kg, compared to 10-15 kg with a single pregnancy. Stretch marks, bloating, varicose veins and haemorrhoids are all more common in a twin pregnancy. 

To know for certain if the symptoms one has is indicative of a twin pregnancy, an ultrasound scan can be done.

What can I expect with twin pregnancies? 

Being pregnant with twins is considered a high risk pregnancy. Expectant moms are at a higher risk for complications such as pre-eclampsia, gestational diabetes, preterm labour, and growth problems for the baby. 

To ensure that everything is on track, frequent prenatal visits will be necessary. The OB will get you on a schedule for all the appropriate evaluation that a mom with multiples will need during pregnancy. The goal is to make sure that there are no genetic abnormalities and complications that come with having more than one baby. 

Down syndrome testing is offered routinely around 11-14 weeks similar to any pregnancy. For couples who choose to add on the non invasive prenatal test (NIPT) looking for fetal DNA circulating in maternal blood for the 99% Down syndrome detection rate, some companies eg Panorama are superior to others as they are equipped with the technology to differentiate between identical and fraternal twins (zygosity) and individual gender of each twin at that gestation. This can be an important differentiation as fraternal same sex twins never share a placenta and hence are at lower risk for complications. 

For twin pregnancies where the babies each have their own placenta (dichorionic), ultrasound scans are advised every 4 weeks from the second trimester. For those identical twins who share a placenta (monochorionic), the scans will be scheduled every 2 weeks from 16 weeks of pregnancy onwards. This is to screen and detect associated abnormalities early as sharing a placenta is associated with higher risks of discordant growth from unequal shunting of blood in the placenta. If any problem is suspected, you may undergo blood tests and more frequent ultrasound exams. 

Twins are at a higher risk of birth defects, including neural tube defects like spina bifida as well abnormalities with the digestive tract and heart. During the second trimester an ultrasound around 20 weeks can help check for any structural issues. It’s possible that one baby can have an abnormality, while the other doesn’t.

What are the risks of a twin pregnancy to the babies? 

Multiples have a tendency to have growth problems than single babies. In fact, twins are called discordant if one fetus is much smaller than the others. Even in fraternal twins with separate placentas,they still have a high risk of premature birth or growth restriction. Discordant growth is common with multiples, but it may not always signal a problem if mild (less than 20%). 

There are cases where the babies’ restricted growth are caused by twin-to-twin transfusion syndrome (where the blood flow is shunted from one fetus to the other when sharing a placenta) or problems with placental insufficiency or the umbilical cord. If growth restriction is suspected in one or both fetuses, frequent ultrasound exams may be done to track their growth.

Dr Pamela Tan - Twin to Twin Transfusion Syndrome

Excessive amounts of amniotic fluid (polyhydramnios) is also common in multiple pregnancies and this can predispose to early preterm rupture of the membranes that make up the pregnancy sac and predispose to preterm delivery. Umbilical cord entanglement is common for the rare set of twins that share not just a placenta but also an amniotic sac. In these cases, the fetuses may need to be monitored very often in the third trimester and delivered much earlier than term (before 37 weeks).

It’s also true that the higher the number of babies in a pregnancy, the greater the risk for an early birth. An estimated 60% of twins deliver before term compared to about 8% of singleton pregnancies. Cervical length ultrasound surveillance may help detect patients at higher risk of preterm delivery and vaginal progesterone hormone medication may be started for these individuals. Premature babies are born before their bodies and organs completely mature. For that they may need help breathing, feeding, regulating their body temperature, and in warding off infections. These babies also tend to be small with low birth weights. 

Since preterm babies are not ready for life outside the womb, they need to be placed in a neonatal intensive care unit (NICU).

These risks may be present, but measures can be set to avert or minimise their chances of happening. Prenatal check-ups could not be stressed enough to protect the growth and safety of your twins in the womb.

What are the maternal complications of twin pregnancies?

We have mentioned that twin pregnancy is high risk. It is prone to a number of complications, but it doesn’t mean that it will happen to you.  Knowing what you will be up against with this type of pregnancy helps you to be more cautious as you bring your babies to term.

Here are the maternal complications that you might encounter:

More Pregnancy Discomfort/ symptoms

Twin pregnancies are much more demanding on the body. Patients are much more likely to get excessive nausea and vomiting in the first trimester that may lead to dehydration. The severe form is called hyperemesis gravidarum. Constipation and bloating may be worse. The strains on the pelvic floor muscles lead to higher urinary incontinence and the strain on back muscles are also more significant. These patients will be more likely to have muscle aches starting before the third trimester and develop a diastasis recti (separation of the middle abdominal muscles) that require physiotherapy post partum. Aesthetic considerations like stretch marks, varicose veins and loose abdominal skin post partum are not uncommon. 

Preterm labour and birth

Preterm birth is defined as delivery before 37 weeks of gestation. Labour in twin pregnancy generally occurs before singleton pregnancy. The reason for this is that premature birth in multiples is linked to uterine overdistention. 

Gestational hypertension

Gestational hypertension is a form of high blood pressure (>140/90 mmHg) in pregnancy which is more severe in twin pregnancies. It can develop into preeclampsia, a complication where high blood pressure is accompanied by increased protein in the urine.

You can read more about the dangers of preeclampsia and the potential threats it places on your pregnancy.

Preeclampsia can lead to organ damage, most commonly in your kidneys, liver, brain, and predisposes to abnormal clotting. If left untreated, it can cause dangerous seizures called eclampsia. This severe form of preeclampsia often develops near the end of pregnancy. The babies may need to be delivered early even if they are not fully grown. Taking low dose aspirin prophylactically from 12 weeks may help reduce the risks of developing pre-eclampsia in at-risk pregnancies. 

Dr Pamela Tan - Symptoms of High Blood Pressure In Pregnancy


Pregnancy causes the blood flow in your system to expand and become more diluted. Iron deficiency anemia is common as the babies use iron for red blood cell production. This causes many expectant moms to become anemic without proper supplementatIon. Your blood then lacks enough healthy red blood cells to carry oxygen to your tissues and to your baby. When you’re expecting twins, this can affect you even more, making you extremely tired. More frequent checks for haemoglobin levels are needed for early detection. 

Gestational Diabetes

Gestational diabetes is much more common in twin pregnancies. Patients are routinely screened between 24-28 weeks gestation. This condition can increase the risk of preeclampsia and of developing diabetes mellitus later in life. It can also result in higher risks of prematurity and perinatal death. Diet, exercise, and medication can reduce the risk of these complications.

Are you keen to know more about the dangers of diabetes in pregnancy? Read all about it here.


Twin pregnancies have higher rates of miscarriages which is common in later trimesters. In early pregnancy, a phenomenon called the vanishing twin syndrome is a type of miscarriage in twin pregnancies where the other embryo vanishes (or is miscarried). The fetal tissue that remains from the miscarried twin is absorbed by the surviving baby and the mother.

Caesarean Delivery 

In some cases, twins can be delivered by vaginal birth, however many are delivered via caesarean section. How they are born will depend on their position, weight, health of each baby and any associated pregnancy complications in the mother. More than one third of women who planned a vaginal birth in labour after 32 weeks gestation go on to have a Caesarean section hence choosing a planned caesarean section may seem like the more predictable outcome. 

If the presenting twin nearer to the neck of the womb (cervix) that will be born first is not in a head down (cephalic) position Eg breech position (feet or buttocks come first) or is lying sideways, a c-section is necessary. A c-section is also required in the following instances: 

  • placenta praevia (low-lying placenta)
  • twins share a placenta/ amniotic sac
  • one or both babies are small/ growth restricted or are significantly size discordant.
  • Baby/ babies become distressed in labour as evidenced by heart beat pattern abnormalities
  • blood pressure is high and investigations suggest pre-eclampsia
  • labour is progressing too slowly or assisted vaginal delivery fails eg first baby born vaginally but the second baby has difficulty being delivered

Postpartum Haemorrhage

Postpartum haemorrhage is a more frequent complication in twin pregnancies. Hemorrhage more commonly occurs after the placenta is delivered. With twins, a large placental area and overdistended uterus places a mother at risk for bleeding after giving birth. 

Uncontrolled and excessive blood loss during postpartum can lead to an increased risk of hysterectomy (surgical removal of the uterus), multi-organ failure, and maternal death. However, prompt detection and treatment can often lead to a full recovery.

Expecting twins? Minimise the chances of complications through close monitoring by an OBGYN.

Expecting twins? Minimise the chances of complications through close monitoring by an OBGYN.

How do you eat right for your twins?

Being pregnant with twins requires specific caloric requirements to promote maternal-fetal well-being. Good nutrition also optimises the growth and development of your growing babies. 

There are no specific nutritional guidelines for women pregnant with twins. But evidence suggests that compared to singleton pregnancies, the energy expenditure in twin pregnancies are 10% higher. This results in a 40% increase in caloric requirements. In a study conducted by Luke and colleagues, they suggest a daily caloric intake for twin pregnancies of 3,000-3,500 kcal/day for women of normal weight, 3,250 kcal/day for overweight women, and 2,700-3,000kcal/day for obese women. A study by Goodnight suggested 40-45 cal/kg/ day for women with normal bmi. 

Adequate protein intake is emphasized as essential to normal fetal growth in twin gestations. In addition, iron, folate, calcium, DHA, vitamin D, magnesium and zinc supplementation are also recommended beyond your usual prenatal vitamin.  

The unique physiological demands placed on the body during a twin pregnancy is good reason to seek professional help from health care providers. Your OBGYN or a certified nutritionist can provide counsel on the importance of adequate caloric intake for optimal pregnancy outcomes.

Get customised nutritional counselling that applies to your weight, health condition, and specific dietary requirements.

What do the experts suggest for physical activity in twin pregnancies? 

The American College of Obstetricians and Gynecologists (ACOG) recommends all women with uncomplicated pregnancies engage in 20–30 min of moderate-intensity aerobic physical activity on most or all days of the week (150 min/ week).

There are no specific physical activity guidelines for women pregnant with twins. Given the higher risk for maternal complications in twin pregnancies, it is important that you seek the appropriate counsel first to evaluate the risks and benefits of physical activity for you. It is likely that mothers need to restrict to low impact activity from 20-24 weeks gestation. Swimming, antenatal yoga, pilates and brisk walking or stationary biking are generally recommended activities. It is important to ensure that your heart rate does not go above 140 beats per min while exercising. 

As you develop a bigger bump and more discomfort than if you were carrying just one baby, you may also consider getting leave from work earlier, possibly around 28 weeks. 

What should I include in my birth plan when expecting twins?

The mode of delivery is one of the main considerations that should be included in your birth plan. It will depend on how your pregnancy progresses and when your labour begins. 

As to your date of delivery, it is already expected that you may go into labour early. Even if you don’t, you may be advised to have your babies delivered before the actual due date. This is an elective birth that is done either by inducing labour or by having a c-section. 

The timing of delivery will depend on individual circumstances. Uncomplicated twin pregnancies are advised to undergo elective birth at

– 37 weeks, if the babies have separate placentas

– 36 weeks, if the babies share a placenta

– 32-34 weeks, if sharing an amniotic sac

The administration of antenatal steroids to promote lung maturity before delivery needs to be discussed as the babies would still be preterm and the lungs are the last to develop fully. It should also be offered to mothers of babies delivered via Caesarean sections before 39 weeks gestation to reduce the risk of respiratory distress in the babies. 

Besides the timing, how you deliver your babies are also crucial considerations. Your decision to have a vaginal birth or a c-section will depend on the position of the placenta, how your babies are growing, and whether you have had a previous cesarean section. 

Remember to consider your options carefully and discuss your individual situation with your healthcare team. 

Be well prepared for labour and delivery through a birth plan. Here are simple tips to help you get started!

A Quick Word for Mommies…

Being tagged as a high-risk pregnancy shouldn’t be a cause for worry. High-risk does not mean that something bad will definitely happen to you or your babies. It only implies that you need greater monitoring and have a greater chance of complications from happening.

Preterm labour, growth discordance, caesarean birth and postpartum hemorrhage are some of the major considerations of twin pregnancies. But the likelihood that these may happen relies on many personal factors. 

It helps to talk with other twin moms because these interactions also bear valuable insights. But you also need to carefully filter the information. Choose realistic and evidence-based medical advice. It’s true that complications may happen in any pregnancy, but you don’t need someone who will sensationalise everything that can go wrong. 

Above everything else, find an OBGYN who is equipped to manage twin pregnancies, but also collaborates with a high-risk maternal-fetal medicine specialist and paediatric specialist, known as a perinatologist.  We hope that the information we shared in this blog can help you get a good headstart in this journey. There is more to discuss, and we are open to discuss them in detail with you! Book a no-obligation consultation with Dr Pamela Tan today.