Normal Labour – Maternal & Child Health Lecture

35 Q&A flashcards covering definitions, stages, durations, uterine physiology and mechanical factors of normal labour.

What is labour?

The process by which the fetus, placenta and membranes are expelled through the birth canal, initiated by regular painful contractions with progressive cervical effacement and dilatation.

How does WHO (1999) define normal labour?

Spontaneous in onset, low-risk throughout, vertex presentation between 37–42 completed weeks, ending with mother and infant in good condition.

What constitutes abnormal labour?

Labour patterns that deviate from established normal standards.

What primarily determines the onset of labour?

A complex interaction of maternal and fetal hormones.

What is spurious (false) labour?

Painful contractions that mimic labour but lack cervical effacement and dilatation.

Which two features are absent in spurious labour but present in true labour?

Cervical effacement and cervical dilatation.

List the hallmarks of true labour.

Spontaneous, regular, rhythmic painful uterine contractions with progressive cervical effacement and dilatation.

When does the first stage of labour begin and end?

From 0 cm cervical dilatation to full (10 cm) dilatation.

Name the three phases of the first stage of labour.

Latent phase, Active phase, Transitional phase.

Describe the latent phase.

Lasts about 6–8 h in primigravidae; cervix dilates 0–4 cm and canal shortens from 3 cm to <0.5 cm.

What characterizes the active phase?

More rapid cervical dilatation beginning around 4 cm.

When does the transitional phase occur?

From ~8 cm dilatation to full dilatation or onset of expulsive contractions.

Define the second stage of labour.

From full cervical dilatation to birth of the baby.

Average duration of the second stage in primigravidae vs. multigravidae?

About 1–2 h in primigravidae and 30 min–1 h in multigravidae.

What marks the third stage of labour?

Time from birth of baby to separation and expulsion of placenta and membranes.

How long does placental expulsion usually take?

Generally within 20–30 minutes.

Define the fourth stage of labour and its main clinical focus.

From placental delivery until 4–6 h postpartum; observe for postpartum haemorrhage.

Give four factors that influence the length of the first stage of labour.

Parity, birth interval, psychological state, fetal presentation/position, maternal pelvic shape/size, quality of uterine contractions.

What is cervical effacement?

Thinning and shortening of the cervical canal from 2–3 cm to an obliterated canal leaving only a thin external os.

How do effacement and dilatation progress in primigravida vs. multigravida?

In primigravida effacement precedes dilatation; in multigravida they occur simultaneously.

Define cervical dilatation.

Enlargement of the external os from closed to 10 cm to allow fetal head passage.

What is the Ferguson reflex?

Even pressure on the cervix produces reflex uterine contraction and retraction from the fundus.

List the main elements of uterine action during labour.

Fundal dominance, polarity, contraction & retraction, intensity & resting tone, formation of upper/lower segments, retraction ring.

Explain fundal dominance.

Each contraction starts in the fundus, spreads downward, peaks simultaneously, and fades together—facilitating cervical dilatation and fetal expulsion.

What is uterine polarity?

Neuromuscular harmony where the upper pole contracts strongly/retracts while the lower pole contracts slightly/dilates; loss of polarity inhibits labour progress.

Differentiate contraction and retraction.

Contraction: active muscle shortening; Retraction: partial, permanent shortening retained after each contraction, shortening the upper segment cavity.

How do contraction frequency and intensity evolve as labour progresses?

Frequency increases to 3–4 contractions per 10 min; intensity greatest at fundus; resting intervals shorten as duration and strength rise.

What forms the lower uterine segment (LUS)?

Stretching and elongation of the isthmus as longitudinal fibres retract and pull on lower circular fibres.

Define the physiological retraction ring.

The junction between upper and lower uterine segments that rises as labour progresses.

When is Bandl’s ring observed clinically?

When the retraction ring becomes visible in obstructed labour.

How are forewaters and hindwaters created?

Detachment of chorion from decidua lets the protruded sac bulge; fluid ahead of the head forms forewaters, fluid around body forms hindwaters.

What is general fluid pressure and its significance?

Uniform pressure on amniotic fluid during contractions; maintains fetal oxygenation and helps prevent intra-uterine infection.

Describe fetal axis pressure.

Uterine force transmitted along fetal long axis to presenting part and cervix during each contraction.

Why is a supportive, non-intervention environment important during birth?

Birth is physiological; minimal intervention and supportive surroundings empower the woman and promote normal progress.

What is the midwife’s primary responsibility regarding labour onset and changes?

Remain sensitive to emerging signs to provide timely support and care for mother and baby.