• Babies are considered full-term at 37 weeks.pregnant woman image by Frenk_Danielle Kaufmann from Fotolia.com
  
  A premature delivery can cause adverse health effects to both mother and child. Pregnant women can undertake a number of steps to ensure their babies are delivered on time and in full health. These include cutting out drinking and smoking and ensuring they receive essential nutrients to promote healthy body growth. There are some conditions, however, that predispose certain women to the risk of premature deliveries.
  
  

Preeclampsia

• A woman suffering from preeclampsia keeps excessive fluid in her body, resulting in high blood pressure and excess levels of protein in her urine. This can interrupt the regular blood flow from mother to baby via the placenta. A healthy placenta is a baby's lifeline, so it needs to be constantly supplied with essential nutrients and oxygen. If untreated, preeclampsia can lead to premature deliveries and dangerously low body weight in babies.
  
  The exact causes of preeclampsia are not known, but it is more typical in pregnant women carrying twins or triplets. It is also more common in first-time mothers and in women with a family history of diabetes. Getting regular hospital checkups during pregnancy where blood pressure and urine content are examined can help detect preeclampsia early.
  
  

Membrane Rupture

• According to Health News, membrane ruptures are one of the most common causes of early births. Ruptures occur when the sac holding the baby breaks completely or is punctured prior to labor beginning. This results in a leak of the amniotic fluid that protects the baby.
  
  Medical experts are unsure as to the exact causes of membrane ruptures, but vaginal infections or overproduction of amniotic fluids could play a part. Membrane ruptures cannot be prevented with medication, but doctors may prescribe tocolytics, which can prevent the onset of labor so a baby has additional time to develop.
  
  

Weakened Cervix

• The cervix should soften at the latter stages of pregnancy, dilating as contractions arrive. In some cases, however, a baby develops and starts to push on the cervix. This results in the cervix opening prematurely, when a baby is not fully developed. According to Health News, early birth due to a weakened cervix happens in around 1 percent of all pregnancies. A doctor may perform a cerclage in such cases, where the cervix is sewn shut around the 15th week of pregnancy and reopened around the 37th week, when a safe, healthy birth is more likely.
  
  

Abnormal Uterus and Age

• There are a range of uterine abnormalities that can afflict women during pregnancy. Each results in a baby having restricted space to develop compared to a normally shaped womb. If the uterine growth is restricted, a baby eventually runs out of space to develop, causing pressure on the womb and the onset of premature labor.
  
  Age can also be a significant factor in premature births. According to the March of Dimes, women over the age of 40 are more likely to experience premature deliveries than younger women.