Twin pregnancy complications

Many of the usual problems of pregnancy start sooner and are exaggerated. Nausea may be more bothersome because of the higher level of circulating hormones. Heartburn, indigestion and the need to urinate frequently are more likely as the enlarging uterus presses on other organs. Back pain is common because of the extra load combined with the ligament-relaxing effects of pregnancy hormones. Sleep problems, piles and varicose veins are all more likely to develop.

More serious complications of pregnancy are also possible. Threatened miscarriage occurs more often and, according to some studies, so does vaginal bleeding, perhaps partly because one or both placentas are lying low in the uterus.

It is now known that in some cases a twin dies in the womb in the early weeks, leaving a healthy survivor. An ultrasound at four to six weeks reveals two tiny pregnancy sacs but by 12 weeks one of the sacs has been reabsorbed back into the body.

Until around 28 weeks, twins’ growth rate is usually normal. But then some babies do not grow as fast as they should. Intrauterine growth retardation is carefully monitored by ultrasound scans.

In a few multiple pregnancies, too much amniotic fluid builds up (polyhydramnios), making life very uncomfortable for the mother. The fluid can be drawn off by amniocentesis but a premature labour may follow or bed rest may be advised.

Pregnancy hypertension (high blood pressure) and pre-eclampsia are also more frequent, and may mean that the babies need to be delivered early.

Premature labour is the main risk of twin pregnancy, probably caused by the uterus overstretching. Four out of ten twin pregnancies (more with identical twins) go into labour before 37 weeks. Going into hospital means that the condition of the babies can be monitored but preventing a premature birth may not be possible.