NHS Suffolk and North East Essex - Labour and Birth Booklet

17 What to expect in labour and birth Preterm birth carries risks because babies who are born too soon may not be fully developed, and need specialist help for life outside of the womb. Preterm babies are also at risk of longer term health problems. Causes of preterm birth A baby may be born prematurely as a result of preterm labour or because an earlier birth is recommended, due to complications that may have arisen during the pregnancy (affecting the mother or the baby). In many cases, it is not clear why labour starts early, however factors known to increase the risk of preterm labour include the following: • premature rupture of the membranes (your water’s breaking early) • some infections, such as chorioamnionitis, which effects the membranes and amniotic fluid protecting the baby • multiple pregnancy (the average twin pregnancy is 37 weeks in length, and the average triplet pregnancy is 33 weeks in length) • previous preterm birth • having a placenta that is ‘low-lying’ (meaning it either partially or completely covers the cervix) or having a placental abruption (meaning the placenta starts to separate from the wall of the womb) • maternal medical conditions, including diabetes or conditions linked to inflammation (eg. Crohns disease) • being a smoker, drinking alcohol or using illegal substances • low Body Mass Index (having a weight that is considered to be low for your height) • biopsy’s or LLETZ treatments to remove abnormal cervical cells • having a weak cervix that might open during pregnancy • polyhydramnios (excessive amniotic fluid) • intra-hepatic cholestasis of pregnancy (a pregnancy condition effecting your liver) • abnormalities of the shape of the womb.