Obviously, carrying and delivering two babies at once is more difficult than just producing one.Statistically, it's true that there’s likely to be more problems carrying twins. However, not all complications of single pregnancies occur more frequently in a twin pregnancy.
How twin pregnancies happen
Identical twins. One egg splits after fertilisation into two separate cells – each one of these growing into a baby (usually sharing the same placenta). Having developed from the same cell, they are always the same sex and look alike.
Non-identical or fraternal twins. Two eggs are fertilised by two different sperm at the same time and each baby has its own placent. They can be different sexes and probably will not look any more alike than any brother or sister.
Your chance of having twins
Twin pregnancies are passed down through the female and are more likely to occur if there are already non-identical twins in the family. The prevalence in the UK is about one in 95 deliveries – and this has been increasing over the past couple of decades. Multiple pregnancies also increase as women get older.
Diagnosis
Twin pregnancy used to be diagnosed when the mother reported that her symptoms of pregnancy were worse than usual and the womb was found to be bigger than expected for the gestational dates. Nowadays, routine ultrasound scans usually allow a much earlier diagnosis.
Congenital abnormalities.
These are conditions recognised at birth, or believed to have been present since birth – and there is an increased risk of this with a twin pregnancy. For this reason, a very thorough ultrasound examination of each foetus will be performed between 20–24 weeks of gestation. If the ultrasound session seems particularly long and ‘intense’ you’ll know why. If an abnormality is suspected following this ultrasound examination, a further investigation will be required. This may mean an amniocentesis.
Nausea. Early in the pregnancy, you may have more nausea because of the higher concentration of hormone being produced from the placenta.
Veins and other troubles. The increased size of the womb leads to greater pressure on the veins in the legs. This will increase the chances of minor problems such as varicose veins in the legs, haemorrhoids (piles) and sometimes swellings of the veins within the vaginal entrance and these can certainly be uncomfortable and irritable.
Blood pressure. Multiple pregnancies do lead to more problems with high blood pressure and associated problems like eclampsia. So expect your antenatal screenings to be extra thorough.
Rest. Just take it easy!
Hydramnios. This is an abnormally large amount of fluid surrounding the baby. It occurs more commonly in twin pregnancies from about week 20. It can increase all those problems associated with the enlarged womb and adds to any breathlessness you may experience as your pregnancy progresses.
Anaemia. With twins there's generally a higher risk of anaemia. This can be due to the greater expansion in blood volume that occurs in twin pregnancy. Folic acid requirements are also greater because of the risk of anaemia
Growth retardation. This can sometimes occur within the womb and often the twins differ considerably in size from each other. Surprisingly, the difference can be greatest amongst identical twins.
Premature birth. There is an increased risk and this means also that the birth weight of twins can be low.
The average gestation time for single pregnancies is just over 40 weeks. For twins it is only 37 weeks.
Labour starts early in 20–50% of twin pregnancies compared with 5–10% in singleton pregnancies.
Doctors and midwives try to identify those mums likely to go into early labour and prevent this if possible. If it isn’t, they will make sure the babies are delivered in a hospital with neonatal facilities to care for premature babies.
Antenatal care will certainly entail more ultrasound screening, tests and investigations and more appointment sessions.
But at the end of the day, you get double the fun!!
March 2008
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