Information
Editors
KatiTihtonen
AnitaVirtanen
Labour and Delivery
Signs of impending labour
- Labour may be preceded by transient contractions lasting for several hours; they do not always signify the start of true labour.
- The cervical mucus plug, sometimes tinged with blood, is usually released from the cervix 1-7 days before the actual start of labour.
- When labour begins, contractions become more frequent and stronger; contractions lasting for 45-60 seconds occur every 10 minutes or more often. Labour begins when the contractions are at regular intervals and the cervix starts to dilate.
- Labour may begin with uterine contractions or with rupture of the foetal membranes before the start of contractions.
- Full-term delivery occurs after HASH(0x2fdd378) 37+0 gestational weeks.
Stages of labour
- Starts when contractions are regular, and the cervix has dilated to 2-4 cm.
- The cervical dilation stage is divided into a latent stage and an active stage.
- In the latent stage, contractions may come at longer intervals, be of shorter duration and weaker than in the active stage.
- The latent stage can be considered prolonged if it has continued for > 20 h in a nullipara or > 14 h in a multipara, but the time limits vary in the literature.
- The active stage begins when the cervix has dilated to 4-6 cm. Dilation will then speed up, progressing at a rate of about 1 cm per hour. There is individual variation here even if the delivery proceeds normally.
- If in the active stage cervical dilation progresses by < 2 cm / 4 h, the progress of delivery should be assessed.
- The most common causes of prolonged dilation are weak uterine contractions and abnormal foetal presentation.
- Contractions can be intensified by giving oxytocin or rupturing intact membranes artificially, as necessary.
- Foetal presentation in the birth canal can be assessed by palpating sutures and fontanelles in the foetal skull or by ultrasonography.
- The cervix will continue to open until it is fully dilated, i.e. 10 cm. At the same time, the presenting part - head or buttocks- will move further down the birth canal.
- Over 90% of nulliparas will require pain relief. Pain relief methods include
- The second stage of labour begins with full dilation of the cervix.
- It can be divided into a passive descending stage and an active expulsion stage.
- The mother does not always feel an immediate urge to bear down when the cervix is fully dilated. If so, the presenting foetal part should be allowed to descend to the pelvic floor.
- The descent of the presenting part in the birth canal triggers the bearing down urge, and the patient can start bearing down actively.
- Pain relief methods used in the second stage of labour include spinal and pudendal anaesthesia.
- The second stage ends with the birth of the baby.
- Episiotomy should only be carried out as necessary Episiotomy for Vaginal Birth.
- It is important to support the perineum during the expulsion stage in order to avoid tearing.
- There are several different labour positions (e.g. semi-sitting, squatting, on hands and knees) and aids, such as a birthing stool. The mother is usually the best person to choose the optimum birthing position Woman's Position during Second Stage of Labour. If assisted delivery is indicated, it is safest for the mother to be placed in a semi-sitting position on a delivery table with the legs supported in stirrups.
- For nulliparas, > 3 h is the suggested limit for defining a prolonged second stage in women who have had epidural anaesthesia, and > 2 h in those without. The corresponding limits for multiparas are 2 h and 1 h, respectively. When assessing whether delivery is prolonged, not only time limits should be considered but also the mother's individual resources and how the foetus is coping.
- The feasibility of vaginal delivery or the need for operative (vacuum-assisted) vaginal delivery is often assessed if active bearing down continues for > 1-1.5 h.
- Delivery of the placenta and foetal membranes.
- To promote separation of the placenta and to prevent postpartum haemorrhage, mothers are routinely given oxytocin intramuscularly.
- Contractions normally separate the placenta in 5-10 min.
- The placenta and foetal membranes can be delivered by drawing gently on the umbilical cord and applying transabdominal pressure on the uterus.
- Separation of the placenta can be promoted also by massaging the uterus.
- If the placenta has not been expelled within 1 hour of delivery of the child, the third stage should be considered to be abnormal and manual separation and removal of the placenta under operating room conditions may be necessary.
- Bleeding in vaginal delivery can be considered normal if it does not exceed 500 ml.
- Spontaneous vaginal delivery
- Assisted vaginal delivery (assisted breech delivery < 1%, vacuum extraction 10%, forceps delivery and other assisted vaginal delivery procedures)
- Caesarean section 17-20%
- Percentages may vary across countries. Find out about local portions.
Induction of labour
- Usually, labour starts spontaneously. In industrialized countries, about 1 out of 4 cases the labour is induced, and in some countries 30% or more http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6823899/.
- Indications Induction of Labour for Suspected Fetal Macrosomia, Interventions for Improving the Outcome of Delivery at or Beyond Term, Treatment of Premature Rupture of Membranes, Amniotic Fluid Index Versus Single Deepest Vertical Pocket as a Screening Test for Preventing Adverse Pregnancy Outcome
- The most common induction methods Oral Misoprostol for Induction of Labour, Vaginal Prostaglandin (Pge2 and Pgf2a) for Induction of Labour at Term, Intravenous Oxytocin Alone for Cervical Ripening and Induction of Labour, Amniotomy for Induction of Labour, Foley Catheter for Induction of Labour at Term, Amniotomy Plus Intravenous Oxytocin for Induction of Labour, Mifepristone for Induction of Labour, Breast Stimulation for Cervical Ripening and Induction of Labour, Antipsychotic Medication for Childhood-Onset Schizophrenia, Membrane Sweeping for Induction of Labour
- Indications for vacuum extraction (ventouse delivery): stagnation of delivery, impending foetal oxygen deficiency or acute emergency during delivery when the cervix is fully dilated
- There are several types of suction cups: rigid cup, silicone cup, disposable cup
- Episiotomy is almost always performed but is not absolutely necessary.
- Forceps delivery is another, rarely used form of assisted delivery.
- The benefit of forceps is that they are quick to use; they are often used in association with difficult expulsion.
- About half of caesarean sections are elective procedures, the rest are carried out when unforeseen complications arise during labour. Caesarean section is usually carried out under regional anaesthesia via a Pfannenstiel incision, i.e. transverse incision above the pubic bone.
- The most common indications for caesarean section are cephalopelvic disproportion, stagnation of delivery, previous caesarean section, impending foetal oxygen deficiency, mother's chronic disease or severe pregnancy complication, breech presentation, and strong fear of delivery.
- Emergency caesarean section (about 1% of all deliveries) is carried out under general anaesthesia often via a low vertical incision to facilitate quick delivery of the infant.
- Caesarean delivery is associated with a higher risk of serious complications (venous thrombosis, approx. 2/1 000, haemorrhage 10%, infections 14%, respiratory difficulties in the newborn) than vaginal delivery Method of Delivery and Pregnancy Outcomes.
- Antimicrobial prophylaxis is recommended for all caesarean sections.
- Antithrombotic prophylaxis with low molecular weight heparin is recommended for high-risk mothers.
- External cephalic version should be attempted at 36 weeks weeks of gestation for foetuses in breech presentation, particularly if the mother is not motivated for vaginal delivery of the breech baby External Cephalic Version for Breech Presentation at Term.
- Most foetuses in breech presentation are delivered by caesarean section.
- If the foetus is in breech position, the vaginal delivery plan depends on its size, the mother's motivation and pelvic volume, and the course of the pregnancy.
- Breech delivery requires the skills of staff with experience in this procedure.
- In breech delivery (< 1% of deliveries), spontaneous labour should be allowed to proceed, as far as possible. If the course of delivery is abnormal, caesarean section should be performed, as necessary.
- At the expulsion stage, the mother needs to push the infant out until the shoulder blades are visible, and a physician will then employ special manoeuvres to deliver the shoulders and head.
- Pain relief options are the same as in cephalic presentation.
Shoulder dystocia
- Shoulder dystocia refers to a state where the foetal shoulders become impacted following delivery of the head.
- Its most common risk factors include large foetus (> 4 500 g), maternal diabetes (an independent risk factor) and obesity, prolonged labour, history of shoulder dystocia.
- Special procedures need to be employed to deliver the shoulders in order to avoid brachial plexus injury.
Twin delivery
- About 60% of twin deliveries are preterm (< 37 gestational weeks), which affects the choice of delivery method.
- About half of twin deliveries are by caesarean section.
- The presentation of the leading twin A, in particular, affects the choice of delivery method.
- Vaginal delivery is the primary option if the twin pregnancy proceeded normally, provided that twin A is in occipital presentation and all other prerequisites for vaginal delivery are fulfilled Planned Caesarean Section for Women with a Twin Pregnancy.
- After the delivery of twin A, twin B should be moved into and held in a vertical position if this does not occur spontaneously. The position of twin B in the birth canal can be adjusted transabdominally, as necessary. The delivery of twin B may need to be assisted with a vacuum extraction or breech extraction.
Management of delivery when the mother has a blood-borne infection
- During delivery, hepatitis C and B as well as HIV may be transmitted to the foetus, and theoretically to the attending staff.
- Hepatitis will not affect the choice of delivery method.
- In the case of HIV infection, the delivery method will depend on the mother's viral load.
- Contamination with blood or secretions should be avoided during delivery.
- Invasive procedures, such as amniotomy or placing an electrode on the foetal head or vacuum extraction, should be avoided as far as possible.
- The neonate should be bathed soon after delivery, before protective vaccination or the administration of vitamin K.
- Mothers with hepatitis can be allowed to breastfeed their babies.
- For mothers with HIV, breastfeeding is not recommended.
- Involves postpartum monitoring of the mother and child at the maternity hospital for at least 6 hours.
- A paediatrician examines the infant immediately before discharge and again at an outpatients' clinic in about 3-5 days in order to detect congenital heart defects, for example.
- There are more criteria for assessment of the mother's and infant's wellbeing and the course of the delivery if early postpartum discharge is considered.
- A planned home birth involves a midwife who also has the expertise to refer the mother to a hospital should untoward complications occur during labour.
Preterm labour and delivery
- Preterm delivery is defined as delivery at < 37+0 gestational weeks (5% of cases).
- Specific national or regional recommendations may be available concerning preterm delivery. For example in Finland, it is recommended that delivery at < 32+0 gestational weeks should take place in a specialist maternity hospital. Find out about local recommendations.
- The delivery method should be chosen based on the duration of the pregnancy, number and presentation of foetuses and any pregnancy complications.
- See also Threatened Premature Labour.
Umbilical cord blood sampling
- A sample of blood from the umbilical cord is examined for pH and base excess in order to confirm the well-being of the newborn.
- In a hospital setting a cord blood sample is taken also to detect possible congenital hypothyroidism of the newborn infant. In deliveries taking place outside a hospital it would also be good to obtain a cord blood sample to determine TSH concentration.
References