If you are not in labour and your waters break, this is called premature membrane rupture, or PROM (the word 'premature' relates to the waters going before labour, rather than being to do with how close you are to your due date). PROM can happen either at the end of pregnancy, or earlier on well before the due date. When it happens near the end (after 37 weeks) it is known as term PROM. There is often debate as to what to do when PROM happens at term - some believe that labour should start within 18 hours or the risk of infection outweighs the risks of induction of labour. Others feel that the risk of infection remains low for the next 48 hours and waiting gives the benefit of a more natural start to labour. Most women start contracting within 18-24 hours and if there are no other signs or risks of infection, problems are unlikely and either way to go is reasonable.
Preterm PROM (before 37 weeks) is much more likely to lead to problems and I will talk about this in more detail.
Have my waters actually gone?
This may sound a stupid question but it is not always immediately obvious if they have or not. There are two bags of water in the pelvis, the other, of course, being the bladder, and its not at all unusual for women to leak urine at some time during pregnancy. If there is an ongoing leak, particularly after you have emptied your bladder and it smells sweet, then it may be liquor. There is no foolproof way of telling and if you have any suspicion that your waters may have gone, a doctor or midwife should be consulted for an examination.
An examination will involve palpating your abdomen (to see if it feels like there's less water around the baby) and a speculum examination - like when you have a smear test done. The cervix is visualised and you'll be asked to cough. If the waters have gone, a gush of water is often seen coming out of the cervix. Some clinicians use Amni-stix or nitrizine sticks which change colour when dipped into liquor. These are not 100% accurate and can be falsely positive in the presence of bleeding, with some vaginal infections or if you've had unprotected sex recently. Swabs are also taken to check for infection.
They have gone - what now?
Once it is confirmed that the waters have gone, your obstetrician will discuss with you the plan until delivery. This will depend very much on exactly how far on the pregnancy is and if there are any signs to suggest an infection.
Infection is the main risk to the continuing pregnancy once PROM is confirmed. The amniotic membranes and liquor represent a strong barrier to infection, and once they are broken, bacteria may work their way from the vagina into the womb, causing infection around the baby.
The other main risk to the baby is that of prematurity, should he or she be born now. Prematurely born babies face several problems, the most severe of which can be breathing difficulties, as the lungs are not adequately developed. All the body's systems are immature and premature infants may face many weeks on a special care unit depending on the age at which they are born.
On the whole, the risks of prematurity are the greater of the two, as long as there's no obvious signs of infection. Infections can cause fever, tenderness over the womb, or a change in colour of the liquor that is coming out. Once infection sets in, the balance of risk is almost always in the other direction and delivery would be expedited - often labour starts itself because of infection, sometimes induction or caesarean section is needed, depending on other factors.
How long until labour starts naturally?
At the end of pregnancy when the waters go, about 80% of women will start contracting within 24 hours. The earlier PROM occurs, the longer is the time until contractions start spontaneously. At 30-32 weeks, the average is about 1 week, and at 25-26 weeks, it is 2 weeks with half of the babies having delivered after the first week.
Can the membranes 'reseal'?
Sometimes there can be an ongoing loss of water, but the pregnancy still manages to lasts until close to term. 'Resealing' of the membranes is also possible: one study found this to happen in 3 of 31 (9.7%) women with PROM at less than 26 weeks and 5 of 189 (2.6%) at 26-34 weeks. So, it does happen, but is unusual.
Further treatments - steroids, antibiotics and stopping labour.
Steroid injections are prescribed if you are less than 34 weeks gestation to help mature the baby's lungs. They aren't the type of steroids that make you muscular, but they stimulate the fetal lungs to prepare for breathing air. Should you not go on to deliver early however, they do not do any harm, so there are really no draw backs to having them.
Sometimes drugs are used to stop labour to allow the steroid course to be completed - this normally takes about 24-36 hours. Also labour may be stopped if you need to be transferred to a hospital better able to care for a premature baby.
Antibiotic tablets will be recommended as they have been found to both prolong the time your baby stays inside and reduce the risk of infections when he or she is born. The usual antibiotic is called erythromycin which is taken in tablet form. When labour starts, the obstetrician may discuss antibiotics through a drip during labour to prevent group B strep disease, which is the most common cause of neonatal infection.
Looking for the development of infection
In the time between the PROM being diagnosed and labour starting, there seems to be little consensus on exactly where women should be managed. Many obstetricians prefer women to remain in hospital during this time. This allows a regular check on temperature, heart rate and look out for the signs of infection. Twice weekly blood tests looking for evidence of a response to infection and weekly vaginal swabs are often recommended.
Some obstetricians however feel that there are a group of women who may be managed at home after an initial period in the hospital. Daily temperature checks are recommended and the other investigations mentioned above can be done on a drop-in basis. Other factors that come into play when making this decision include the distance you live from the hospital and whether the baby is presenting head first.
What are the chance of the baby surviving and being healthy if born early?
This is something that a neonatologist from the neonatal unit will be able to discuss. Survival rates vary in different parts of the world and in different units. In New Zealand, when delivery occurs after 30 weeks gestation, the outlook for the baby is extremely good, all other things being equal. Between 28-30 weeks there is still a good chance of a normal outcome, although some infants will run into problems. An infant delivering at 24-25 weeks can be expected to have a difficult time on a neonatal unit, and unfortunately many do not survive or may be left with significant handicap. Every day between 25 and 28 weeks is important and chance of survival without long-term problems gradually improves. These are of course generalisations, and individual factors will apply.
What about very early membrane rupture?
At 20-23 weeks survival is unfortunately poor (20-25%) and there is a high incidence of handicap in those who do live. PROM before 20 weeks gestation is associated with significant risk of infection and survival chance is negligible, and usually then with significant handicap. After discussion, many women elect termination of pregnancy in this case to protect the mother from what can sometimes be an overwhelming infection. Unfortunately there is no therapy available to replace the fluid or, at present, to plug the hole in the membranes.