is that occurring after 37 weeks' gestation. It should result in the spontaneous vaginal delivery of the baby within 24h of the onset of regular spontaneous contractions. It is often heralded by ashow, ie a plug of cervical mucus and a little blood as the membranes strip from the os. The membranes may then rupture.
The first stage of labour
is the time from the onset of regular contractions until the cervix is fully dilated (no cervix felt around the head). The cervix initially effaces (becomes shorter and softer) before it dilates. A satisfactory rate of dilatation from 3cm dilated is 1cm/h. The first stage generally takes up to 12h in a primip, and 7.5h in a multip. During the first stage check maternal pulse, BP, and T° half-hourly; assess the contractions every 15min, their strength (you should not be able to indent the uterus with the fingers during a contraction) and their frequency (ideally 3-4 per 10min, lasting up to 1min). Carry out vaginal examination eg every 4h to assess the degree of cervical dilatation, the position and the station of the head (measured in cm above the ischial spines) and note the degree of moulding (p 42). Note the state of the liquor (see p 72). Test maternal urine 4-hourly for ketones and protein. If the mother becomes ketotic set up an IVI and give her 10% dextrose.1 Measure the fetal heart rate (if not being continuously monitored) every 15min. Note the rate before, during, and immediately after a contraction.
The second stage
is the time from complete cervical dilatation until the baby is born.
The mother has an urge to push and uses abdominal muscles and the Valsalva manoeuvre to help move the baby. As the head descends, the perineum stretches and the anus gapes. Normal time for second stage is 45-120min in a primip, and 15-45min in a multip. Prevent a precipitate delivery (and so intracranial bleeding) by pressure over the perineum.
Delay in clamping the cord for 30sec and holding the baby 20cm below the introitus results in higher haematocrit levels, so reducing transfusion and oxygen supplement requirements in premature babies.
The third stage
is delivery of the placenta. As the uterus contracts to a <24-week size after the baby is born, the placenta separates from the uterus through the spongy layer of the decidua basalis. It then buckles and a small amount of retroplacental haemorrhage aids its removal.
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