Induction of Labour

For many pregnant women, the onset of labour occurs spontaneously and without complications. However in some cases, labour is initiated or induced by obstetricians when it is considered in the best interests of the mother and child to do so.

The reasons for inducing labour include (but are not limited to):

• Post-dates pregnancy: pregnancy that continues beyond 41 weeks¹ (this is the most common reason and occurs in about 10% of cases²)
• Pre-eclampsia: a syndrome involving several body systems that is characterised by the onset of hypertension (high blood pressure) in thesecond half of the pregnancy³. It occurs in 3 – 5% of all pregnancies³.
• Maternal medical problems e.g. Type 1 Diabetes⁴

Labour induction involves stimulating the uterus to contract prior to the onset of natural labour⁴. Various methods can be used to achieve this. Before inducing contractions, the patient’s cervix needs to be favourable – i.e. the cervix should be softening, dilating (opening) and effacing (stretching)⁵. This process is also called ‘ripening’.

The naturally-occurring hormone oxytocin drives the uterus to contract, pushing the baby down towards the cervix⁶. Prostaglandins, which also occur naturally in the human body, are also released in preparation for childbirth, and set in motion the processes that soften the cervix. Prostaglandins cause the cervix to become thinner and to dilate (open), making it ready for the baby to pass through⁵.

When labour is induced with an unfavourable, or unripe cervix, complications can occur (such as an assisted vaginal delivery, or a need for a caesarean section⁷). It is therefore necessary to prepare the cervix for labour prior to stimulating the uterus to contract⁴. The most widely-used agent for ripening the cervix is Prostaglandin E₂, administered into the vagina or into the cervix². Prostaglandins can also be used for the induction of labour, as they play a role in the contraction of the uterus⁵.

References

¹ WHO recommendations for induction of labour. WHO Press (2011)

² Saeed GA et al. Misoprostol for term labor induction: A randomized controlled trial. Taiwanese Journal of Obstetrics and Gynecology  (2011) 50:15-19

³ Pettit F & Brown MA. The management of pre-eclampsia: what we think we know. European Journal of Obstetrics and Gynecology and Reproductive Biology (2012) 160:6-12

⁴ McCarthy FP & Kenny LC. Induction of Labour. Obstetrics, Gynaecology and Reproductive Medicine (2011) 12(1):1-6

⁵ Hawkins JS & Wing DA. Current pharmacotherapy options for labor induction. Expert Opin. Pharmacother. (2012) 13(14):2005-2014

⁶ Waugh A & Grant A. Ross and Wilson Anatomy and Physiology in Health and Illness. Churchill Livingstone (2007)

⁷ Triglia MT et al. A randomized controlled trial of 24-hour vaginal dinoprostone pessary compared to gel for induction of labor in term pregnancies with a Bishop score ≤ 4. Acta Obstreticia et Gynecologia. Early Online:1-7 (2010)

Preterm Labour

Spontaneous preterm labour is defined as the onset of regular, painful uterine contractions occurring before 37 completed weeks of gestation¹. If preterm labour cannot be successfully suppressed, it may lead to premature birth of the baby. 40 – 50% of all preterm births are associated with the onset of spontaneous preterm labour². In Africa, the incidence of preterm birth is 11.9% of all pregnancies².

Preterm birth can be divided into the following categories, according to the gestational age³:

Extremely preterm                <28 weeks

Very preterm                         28 to <32 weeks

Moderate to late preterm      32 to <37 weeks

In many cases, no definitive cause for preterm labour or preterm birth can be identified. However, risk factors include multiple pregnancies, infections, and maternal conditions such as diabetes and high blood pressure³.

Babies who are born prematurely have an increased risk of death and disability⁴. This risk generally decreases the longer the pregnancy continues. In light of this, attempts will be made to suppress preterm labour and delay delivery of the baby until foetal maturity is reached². Suppression of preterm labour is called ‘Tocolysis’.

Reference:

¹Sanu O & Lamont RF. Critical appraisal and clinical utility of atosiban in the management of preterm labour. Therapeutics and Clinical Risk Management 6:191-199 (2010)

²Wex J et al. Atosiban versus betamimetics in the treatment of preterm labour in Italy: clinical and economic importance of side-effects. Eur J Obstet Gynecol 157:128-135 (2011)

³March of Dimes, PMNCH, Save the Children, WHO. Born Too Soon: The Global Action Report on Preterm Birth. Eds CP Howson, MV Kinney, JE Lawn. World Health Organization. Geneva, 2012

⁴rediction and Prevention of Preterm Birth. Practice Bulletin No. 130. American College of Obstetricians and Gynecologists. Obstet Gynecol 120(4):964-73 (2012)

Postpartum Haemorrhage

Primary Postpartum Haemorrhage (PPH) is excessive bleeding that occurs within the first 24 hours following the delivery of a baby. It is traditionally defined as a blood loss of greater than 500 ml following vaginal delivery, and greater than 1,000 ml following delivery by caesarean section¹.

Postpartum haemorrhage is the most common cause of maternal death worldwide, and occurs in 5% of all deliveries. Non-fatal postpartum haemorrhage can result in further complications such as iron deficiency anaemia and organ damage¹.

The most common cause of postpartum haemorrhage is uterine atony (the inability of the uterus to contract) following delivery of the baby. One of the ways of preventing postpartum haemorrhage is by routine administration of uterotonic medication after delivery. Uterotonic medicines assist the uterus to contract, thereby reducing blood loss¹.

Other causes of postpartum haemorrhage are a retained placenta; trauma to the vagina, cervix or uterus; and blood-clotting dosorders¹.

Reference:

¹.Leduc D, et al. Active management of the third stage of labour: Prevention and treatment of postpartum haemorrhage. Int J Gynecol Obstet 31(10) 980-993 (2009)