style="text-decoration: underline;">risk factors

previous preterm births

multiple pregnancies.the more the babies the higher the risks

low weight gain during pregnancy

vaginal bleeding.

extreme stress or trauma especially if the mother is experiencing  chronic severe  stress.

chronic maternal illness.

poor nutritional status of the mother.

addiction to drugs and alcohol

some causes can be prevented while others cannot.problems with placenta e.g placentaprevia(occur when placenta is located at the begining of the cervix) and placenta abruption(occur when placenta begin to separate from the wall of uterus can cause preterm labor.
some of adngerous chronic illness include:diabetes,sickle cell anaemia,hepatitis and lupus.mothers should monitor their health throughout the pregnancy.
vaginal infections such as chlamydia,trichomoniasis,and bacterial vaginosis are thought to be culprit also.
a large uterus can also lead to preterm labor.this is due to excess amniotic fluid.
your doctor should evaluate your risk factors monitor your health and attempt to reduce them.
the dangers to the baby depends on how far along the pregnancy labor begins.in most cases labor after 34 weeks the baby is fine.the earier the labor begins the more the risk to the baby.