If rupture of the membranes happens before about 26 weeks, the baby is left developing in a confined space with no fluid to allow expansion as it grows, so there are often postural and limb deformities as well as underdevelopment of the lungs. The risk of infection in these cases is very small. In most hospitals the policy is to keep an eye on the woman and offer induction of labour, especially if signs of infection develop. Sometimes PROM happens after an amniocentesis test at 16-18 weeks. At such an early stage the unborn child is almost always lost.
Treatment is aimed to keep the baby safe in the womb for as long as possible.
Vaginal examinations are not done because of the risk that infection might be introduced. If there is any sign of infection, fetal distress or advanced labour then it's essential to deliver the baby as soon as possible. The main possible risk is to its lungs. They may also give her antibiotics although the value of these is not so clear. Very very occasionally, the defect in the membranes seals up, the amniotic fluid fills up again and the woman is allowed home.