Labour has no definite starting point. It usually starts within 2 weeks (before or after) of the estimated date of delivery. Exactly what causes labour to start is unknown, it may be oxytocin (a hormone that is released by the pituitary gland and causes the uterus to contract during labour). The neck of the uterus (the cervix) changes over a period of days in the early part of labour. You will probably not be aware that anything is happening. You may have several days of period-like pains or backache. Eventually it becomes obvious that your baby is coming. The following events usually occur but they do not necessarily follow a given order and may not all occur.
The baby’s head engages
This happens at about 38 weeks (your baby may move in and out of your pelvis with subsequent pregnancies, as it’s not quite such a snug fit after the first). This will probably be picked up at one of your visits by the midwife or doctor who can tell by feeling your abdomen. You will feel the slight pressure of this on your pelvic floor, between your legs, and you may need to pass urine more often as your baby will be pressing on your bladder. However, you will feel less breathless: as your baby moves down you will have less pressure on your diaphragm. Do not be worried if this does not happen as it can take right up to the last minute.
Weight loss and diarrhoea
These two may be connected, as it’s common to have a stomach upset in the days before you go into labour – your bowel needs to be fairly empty for labour to really get going. It’s thought that the hormones that trigger labour also stimulate your bowel to empty. Many women lose around 0.9-1:4kg (2-3lb) in the last days before going into labour.
You have a show
This is a blood-stained mucus discharge which happens as your cervix softens and pulls itself up. During pregnancy the mucus has acted like a plug, protecting the uterus (womb). A show can happen in early labour or two weeks beforehand, so don’t rush straight to hospital, but do feel encouraged that things are beginning to happen.
Your waters break
This is when the pressure of your baby’s head against the sac of membranes in which he has been protected, causes the sac to pop. You will feel a gush of water, or a trickle which doesn’t dry up. It can happen any time before or during labour. Contact your midwife or the hospital as soon as it happens. If your baby is due you can probably wait 24 hours to see if labour begins, if not you will be induced, due to the risk of infection to your baby. If the waters are clear, your baby’s head is engaged and you’re not having any problems there’s no rush to go to hospital, but speak to your midwife for advice.
Contractions may be the first sign you get that you have started labour. Women don’t always notice that they’ve had a show and the waters may not break until labour is well underway. Sometimes the midwife will break the waters for you.
These usually start slowly, feeling a bit like period pain and sometimes you have a backache. Contractions increase in frequency and intensity, rising like a wave then subsiding and going away completely, giving you a short break before the next one.
First-time mums generally have a longer labour, but everyone is different. If your contractions start at home, make sure you keep in touch with your midwife or the delivery suite if you are having your baby in hospital. They will probably advise you to stay at home while you still feel comfortable, but as soon as you feel the need you should go to hospital.