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Types of Twins

Twins can either be identical or non-identical. Identical twins develop from one embryo that divides very early after fertilisation to create two separate babies. Non-identical twins develop from 2 eggs, which are fertilised by 2 sperm and just happen to be growing in the uterus at the same time. Non- identical twins will always have their own sacs and placentas. Identical twins can have their own sacs and placentas (dichorionic), can share a placenta (monochorionic), can share a sac (monoamniotic) and can rarely even share body parts (conjoined), depending on when the embryo splits in two. An early ultrasound will be able to define the number of placentas but not always whether or not the babies are identical. Knowing how many placentas there are is important in helping determine many aspects to your antenatal care, including how often ultrasounds need to be done throughout the pregnancy.

Nausea and vomiting in early pregnancy

This is more common with twins and can be more severe. Initially ginger and B6 tablets may be enough to alleviate nausea. Eating frequently and plain food such as dry crackers can help. Sometimes anti nausea medication such as maxalon, stemetil ondansetron is required. Some women even need to be hospitalized for rehydration. Don’t worry about taking iron, multivitamins or calcium as they will often exacerbate the nausea – start on these again once you are feeling better. Try to take I-folic instead.


A healthy balanced diet is important. In addition to this iron 30mg, folate 0.5 mg and calcium 1000 mg per day are advised e.g. Caltrate 600 mg 2 tablets morning and Fefol or FGF 1 tablet evening, as well as a pregnancy multivitamin e.g. ‘Blackmores Pregnancy Gold’. If you have dietary restrictions additional supplements may be required.

Monitoring growth of twins

Ultrasounds are arranged at intervals throughout the pregnancy. This differs
depending on how many placentas there are and if other complications are developing.
All twins – dating scan 10 weeks, nuchal translucency 12 weeks, morphology 18 weeks.
In addition:
Monochorionic twins – scans every 2 weeks from 16 weeks and a foetal echo at 24 weeks. Monchorionic twins have increased risk of heart abnormalities and so this specialised test – the foetal echo – is arranged to check on the babies’ hearts. Monochorionic twins share the same placenta and sometimes blood vessels from one side can pump blood to the other baby. This results in one baby “stealing” blood from the other. This condition is called twin-twin transfusion syndrome. It occurs in 15% of monochorionic twin pregnancies. Regular ultrasounds will detect if this is occurring. If you experience a sudden increase in the size of your abdomen it can also be an indicator of this occurring and it is important to contact me.
Dichorionic twins – scans every 4 weeks from 24 weeks, sometimes more often if there are concerns regarding growth.

Complications occurring more frequently with twin pregnancies

Premature labour
Labour is more likely to occur early with a multiple pregnancy. Occasionally this can occur before the babies have developed enough to survive. Signs of premature labour can be: period like pain in the lower abdomen or back, tightness or pain around the abdomen, leakage of fluid which may be pink or clear, bleeding or mucous mixed with blood. If you have any of these symptoms please contact me.

This is a condition of high blood pressure in the pregnancy, which can affect your health, and the growth of the babies. It is more common in twin pregnancies. Your blood pressure is checked at each antenatal visit. If you have symptoms including generally feeling unwell, headache, visual disturbance e.g. flashing lights or abdominal pain, it is more important to contact me as these can be symptoms of increased blood pressure. If you develop pre-eclampsia the “cure” is delivery of the babies. Often blood pressure lowering medication is used and sometimes prolonged hospitalisation can be necessary especially if your due date is several weeks away, in order to prolong the pregnancy safely, for as long as possible.

Gestational diabetes
This is also more common in twin pregnancies. You will have a diabetes screen at 16 and 26 weeks. The test takes just over 2 hrs and involves a fasting and 2 hour blood
test after a glucose drink. If diabetes is diagnosed you will need to see a diabetes doctor as well as myself. You will need to monitor blood sugar levels. Diet and exercise are usually enough to control the sugar levels for most women however some will require insulin. The diabetes is usually “cured” by having the babies.

“Term” for dichorionic twins is usually 37-38 weeks and 36 weeks for monochorionic twins. This is due to the increased risk of still birth if the pregnancies are prolonged past this gestation. I recommend a steroid injection for you to help mature the babies’ lungs if a caesarean is planned.
Mode of delivery
If the twins are monochorionic I recommend a caesarean section. If the twins are dichorionic and the lower twin is cephalic (head 1st) we will discuss the pros and cons of vaginal delivery versus caesarean to help you make a decision about delivery. I recommend a caesarean if the lowest twin is not cephalic.
If you plan a caesarean, the usual anaesthetic is a spinal or epidural so that you can be awake and see your babies when they are born. Occasionally some women will need to have a general anaesthetic i.e. be asleep. If you plan a vaginal delivery, I recommend an epidural for two reasons. Labour is exhausting and there are two babies to push out so being able to rest whilst your uterus does the hard work of dilating your cervix is beneficial to your energy reserves. Secondly, if the second baby decides to be breech or transverse, sometimes maneuvers are required to deliver that baby that are better achieved if you have an epidural.

Coping at home with twins
Having one newborn at home is very busy, two is even more so. Attending the twins antenatal classes at the Royal Hospital for Women will provide very helpful information. If you plan to breastfeed attending the antenatal breastfeeding class at the RHW is a good idea. The NSW Multiple Birth Association also has information that you will find useful. I also suggest planning additional maternity leave and taking advantage of any offers of help that you receive from family and friends.