Definitions of Terms in Obstetrics

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ABRUPTIO PLACENTAE

Premature separation of a normally situated placenta (partially or completely) before fetal delivery. Partial or total separation of a normally situated placenta before the delivery of the fetus.

ACTIVE MANAGEMENT OF LABOUR

A proactive approach to labour management, involving timely interventions to prevent or correct complications, ensuring the delivery of a viable baby to a healthy mother. Contrasts with the traditional "wait and see" method.

Strategic management of an already established active phase of labour to achieve cervical dilatation of at least 1 cm/hr, thereby preventing prolonged labour.

ADEQUATE CONTRACTION

Defined as 3 contractions in 10 minutes, each lasting at least 40 seconds.

AMNIOTIC FLUID INDEX (AFI)

The sum of the maximum vertical pocket depth in the four quadrants of the uterus.

Normal (third trimester): 10–25 cm

ANEMIA IN PREGNANCY

Hemoglobin (Hb) <11 g/dL or Packed Cell Volume (PCV) <33%, regardless of gestational age.

ANTENATAL CARE (ANC)

A planned program of education, medical management, and information for pregnant women, aimed at ensuring a safe and satisfying pregnancy and childbirth experience (ACOG definition).

ANTEPARTUM HEMORRHAGE (APH)

Bleeding from the genital tract after the age of viability but before delivery.

ASSISTED BREECH DELIVERY VS. BREECH EXTRACTION

Maternal effort is required for assisted breech delivery at specific points, whereas breech extraction involves manual delivery without maternal effort.

ATTITUDE

Fetal attitude – The relationship of different parts of the fetus to one another in terms of flexion and extension.

Refers to the degree of flexion or extension at the upper cervical spine, describing the relationship of the fetal head to the trunk.

ATYPICAL ECLAMPSIA

Seizures occurring after 10 days postpartum, up to 42 days postpartum.

AUGMENTATION OF LABOUR

Stimulation of uterine contractions that are already present but inadequate in frequency and intensity.

BAD OBSTETRIC HISTORY (BOH)

A woman with a previous pregnancy that had a disastrous outcome.

A woman is said to have BOH if she has had a previous adverse pregnancy outcome that can affect the course and management of the current pregnancy.

BIRTH

Complete expulsion or extraction of a fetus from its mother, regardless of gestational age (GA) or whether the umbilical cord has been cut.

BOOKED PATIENT

A pregnant woman who has had at least one antenatal visit and undergone all necessary investigations to classify her as high or low risk.

BRAXTON HICKS CONTRACTIONS

Painless, irregular uterine contractions that do not cause cervical changes.

CAESAREAN SECTION (C-SECTION)

Surgical delivery of a baby and placenta via an incision made on the uterus through the anterior abdominal wall after the age of viability.

A surgical incision made on the anterior abdominal wall and uterus to deliver the fetus after the age of viability.

CAPUT SUCCEDANEUM (CAPUT)

Edema of the fetal scalp resulting from impaired venous return due to constriction by the cervix.

CEPHALOPELVIC DISPROPORTION (CPD)

An anatomical misfit between the fetal head and the maternal pelvis, despite adequate uterine contractions, in the absence of fetal or maternal distress, often evidenced by moulding and caput formation.

A diagnosis made in labour where there is an anatomical misfit between the fetal head and maternal pelvis, preventing safe vaginal delivery.

CERVICAL DYSTOCIA

Failure of cervical dilation despite adequate uterine contractions, after ruling out other causes of obstruction.

CERVICAL INCOMPETENCE

The inability of the cervix to sustain pregnancy to term due to structural or functional defects.

CERVICAL STASIS

Failure of further cervical dilatation despite adequate uterine contractions, confirmed by at least two examinations.

CLIMBING

Used when the bitrochanteric diameter of the fetal buttocks has passed through the pelvic outlet and reached the vaginal introitus without receding between contractions.

CONTRACTILE FALSE LABOUR

A false labour pattern characterized by at least one contraction every 10 minutes.

CORD PRESENTATION

The umbilical cord is located at or below the level of the presenting fetal part, with intact fetal membranes.

CORD PROLAPSE

The umbilical cord is located below the presenting fetal part, but with ruptured fetal membranes.

CONTRACTED PELVIS

A condition where the fetus fails to attain its genetic growth potential, or where the estimated fetal weight is below the 10th percentile for the gestational age (GA), race, and sex.

CROWNING

The widest diameter of the fetal head has passed through the pelvic outlet and descended to the pelvic floor, with no receding between uterine contractions.

Occurs when the widest diameter of the fetal head has passed through the vulvar outlet and does not recede between contractions.

DESCENT

The proportion of the fetal head palpable above the pelvic brim.

ECLAMPSIA

The occurrence of generalized tonic-clonic seizures in pregnancy, labour, or within 10 days postpartum, in the absence of an underlying neurological cause.

New onset of tonic-clonic convulsions in a preeclamptic patient, not caused by neurological, metabolic, or organic conditions.

ECTOPIC PREGNANCY

The implantation of a fertilized ovum in an abnormal site outside the endometrial cavity.

EFFACEMENT

The shortening and thinning of the cervix as it becomes incorporated into the lower uterine segment.

ELECTIVE CAESAREAN SECTION

A planned caesarean section, where the timing, place, and indication are predetermined before the onset of labour, typically performed at 38 weeks.

ENGAGEMENT

Occurs when the widest diameter of the presenting part passes through the pelvic inlet of the maternal pelvis.

Cephalic presentation → Biparietal diameter
Breech presentation → Bitrochanteric diameter

EPISIOTOMY

A surgical incision made on the perineum to increase the diameter of the vulvar outlet, facilitating vaginal delivery.

EXTERNAL CEPHALIC VERSION (ECV)

A transabdominal manipulation performed to convert a breech presentation to cephalic presentation with the aim of achieving vaginal delivery.

EXTERNAL VERSION

A transabdominal manipulation of a malpresenting fetus to achieve a longitudinal lie.

FAILED INDUCTION

The inability to achieve vaginal delivery after 24 hours of induction.

FALSE LABOUR

A retrospective diagnosis of latent phase contractions that fail to progress to the active phase after 24 hours.

FIXED POINTS ON THE MATERNAL PELVIS

Occipito-anterior (OA) → Iliopectineal line
Occipito-lateral (OL) → Alae of ilium
Occipito-posterior (OP) → Sacroiliac joint
Direct Occipito-anterior (DOA) → Pubic symphysis
Direct Occipito-posterior (DOP) → Sacral promontory

GESTATIONAL DIABETES MELLITUS (GDM)

Carbohydrate intolerance of varying severity, first detected during pregnancy.

GRAVIDITY

The total number of pregnancies a woman has had, regardless of the outcome.

Parturient – A woman in labour
Puerpera – A woman in the puerperium (postpartum period)

GRAND MULTIPARA

A woman who has carried five or more pregnancies beyond the age of viability, regardless of the outcome.

HIGH-RISK PREGNANCY

A pregnancy with an increased risk of adverse outcomes for the mother and/or fetus, compared to the general obstetric population.

A pregnancy with unexpected or unanticipated medical or obstetric conditions that pose an actual or potential risk to the well-being of the mother and/or fetus.

HYPERTENSION IN PREGNANCY

Blood pressure (BP) ≥140/90 mmHg, recorded on two occasions at least 4–6 hours apart.

Additional Criteria:

Mean Arterial Pressure (MAP) >105 mmHg
Increase in MAP by >20 mmHg over booking BP
Increase of ≥30/15 mmHg over booking BP
Single BP reading of 160/110 mmHg

Severe Hypertension:

Single BP reading ≥180/120 mmHg
Increase of ≥60/30 mmHg above booking BP

Formulas:

MAP = (Systolic BP + 2 × Diastolic BP) / 3
Pulse Pressure = Systolic BP - Diastolic BP

HYPEREMESIS GRAVIDARUM

Intractable vomiting in pregnancy, associated with fluid, electrolyte, and nutritional imbalances.

HYPERTONUS

Prolonged uterine contractions lasting more than 60 seconds.

INDUCTION OF LABOUR

The artificial initiation of uterine contractions after the age of viability, with the aim of achieving vaginal delivery.

The artificial initiation of uterine contractions after the age of viability, with intact membranes, to achieve vaginal delivery.

INFORMED CONSENT

The intentional authorization given by an individual with substantial understanding, free from coercion, allowing a professional to perform a specific action mentioned in the consent agreement.

INTER-BIRTH INTERVAL

The period between the last childbirth and the current childbirth.

INTERMITTENT PREVENTIVE THERAPY (IPT)

The use of antimalarial drugs in treatment doses at predefined intervals to clear the burden of presumed malaria parasites.

INTERPREGNANCY INTERVAL

The period from the last childbirth to the first day of the last menstrual period (LMP) of the current pregnancy.

INTRAPARTUM HEMORRHAGE

Bleeding from the genital tract after the delivery of the first twin but before the delivery of the second twin.

INTRAUTERINE GROWTH RESTRICTION (IUGR)

The failure of a fetus to reach its maximum genetic growth potential for its age, sex, and race.

ISOIMMUNIZATION

The development of immune antibodies by an individual in response to foreign antigens from another individual of the same species.

LABOUR

The sudden onset of regular, rhythmic, palpable, painful uterine contractions with associated cervical changes, leading to the expulsion of the product of conception after the age of viability.

A series of events that lead to the expulsion of the products of conception after the age of viability. It is characterized by painful, regular uterine contractions with associated cervical dilatation and effacement, leading to fetal descent and expulsion.

Presence of at least 1 contraction in 10 minutes.

LATE MATERNAL DEATH

Death of a woman from direct or indirect obstetric causes, occurring after 42 days but within one year of pregnancy termination.

LIE

Fetal lie – The relationship between the longitudinal axis of the fetus and the maternal spine.

The relationship between the fetal and maternal spines.

LIGHTENING

A sensation of relief at the epigastrium, felt by a pregnant woman, due to the descent of the presenting part into the pelvis at term.

LOWER UTERINE SEGMENT

The part of the uterus bounded superiorly by the reflection of the utero-vesical peritoneum and inferiorly by the internal os.

MALPOSITION

Any fetal position other than occipito-anterior (OA) or one that makes vaginal delivery unfavorable.

MALPRESENTATION

Any fetal presentation other than vertex.

MASSIVE BLOOD TRANSFUSION

Transfusion of ≥10 units of packed red blood cells within 24 hours or replacement of 50% of total blood volume within 3 hours.

MATERNAL MORTALITY

The death of a woman while pregnant, during labour, or within 42 days after termination of pregnancy, from causes related to or aggravated by pregnancy or its management, excluding accidental or incidental causes.

Death of a woman while pregnant or within 42 days of pregnancy termination, from pregnancy-related causes, excluding incidental or accidental causes.

MATERNAL NEAR MISS

A severe acute maternal morbidity in which the mother would have died but survived complications related to pregnancy, labour, or the puerperium.

MATERNAL REQUEST

The primary caesarean birth of a mother based on her request in the absence of medical or obstetric indications against vaginal delivery.

MECHANISM OF LABOUR

Refers to the various changes in attitude and position of the fetus as it passes through the birth canal during delivery.

MOULDING

The reduction in fetal skull diameter due to relative movement across suture lines as the fetal head negotiates through the birth canal during vaginal delivery.

The relative movement of fetal skull bones across suture lines to aid vaginal delivery by effectively reducing the fetal skull diameter.

Stages of Moulding

0 (No contact) → Sutures do not touch
1 (+ Contact but no overlap) → Sutures touch but do not overlap
2 (++ Reducible overlap) → Sutures overlap but are digitally separable
3 (+++ Irreducible overlap) → Sutures overlap and are non-separable

MORBIDLY ADHERENT PLACENTA

Placenta percreta – Placental invasion beyond the stratum basale, reaching the serosa.
Placenta increta – Placental invasion into the myometrium but not through the serosa.
Placenta accreta – Placental invasion into the myometrium but without penetration.

NORMAL LABOUR

A retrospective diagnosis of labour with spontaneous onset, occurring without uterine stimulation or operative intervention, resulting in the delivery of a healthy baby at a viable age.

OBSTRUCTED LABOUR

A complete halt in the course of labour despite adequate uterine contractions due to mechanical factors, such that delivery can only be achieved by operative intervention.

An absolute condition where there is failure to progress due to failure of descent or cervical dilation, despite adequate uterine contractions, caused by mechanical factors. If unrelieved, it can lead to maternal or fetal morbidity or mortality.

OLIGOHYDRAMNIOS

Amniotic Fluid Index (AFI) <5 cm or maximum vertical pool <2 cm.

OLIGURIA

Urine output of less than 30 mL/hour for 4 hours or <400 mL/24 hours.

PARITY

The number of pregnancies carried beyond viability (28 weeks in Nigeria), regardless of the outcome.

PAROUS EXPERIENCE

Deliveries of a baby after the age of viability, irrespective of the outcome.

PARTOGRAPH

A graphical representation of labour events, documenting maternal and fetal status and all therapeutic interventions plotted against time.

PERINATAL MORTALITY

Death of a fetus after the age of viability, during delivery, and up to one week postnatally.

Stillbirth – Fetal death after the age of viability but before delivery.
Early neonatal death – Death occurring after delivery but within the first week of life.

POLYHYDRAMNIOS

AFI >25 cm or maximum vertical pool >7 cm.

POSITION

The relationship between a reference point on the fetal presenting part (denominator) and a fixed point on the maternal pelvis.

POST-DATE PREGNANCY

A pregnancy extending beyond the expected date of delivery (EDD).

A pregnancy that has exceeded 40 weeks of gestation from the first day of the last menstrual period (LMP).

POST-MATURITY

A paediatric term referring to post-term babies, typically those born more than 2 weeks after their expected date of delivery (EDD).

POST-TERM PREGNANCY

Pregnancy extending beyond 41 weeks + 6 days (≥42 weeks).

POSTPARTUM HEMORRHAGE (PPH)

Bleeding from the genital tract after delivery, meeting any of the following criteria:

Blood loss >500 mL
>10% total blood volume loss
Any amount that compromises cardiovascular stability

Types of PPH:

Primary PPH – Within 24 hours of delivery
Secondary PPH – Between 24 hours and 42 days postpartum

PRECIPITATED LABOUR

Labour in which cervical dilatation progresses at more than 5 cm/hour, or the active phase lasts less than 3 hours.

PRE-ECLAMPSIA

The presence of elevated blood pressure with significant proteinuria after 20 weeks of gestation.

Hypertension + proteinuria ± oedema, occurring after 20 weeks of gestation, in a previously normotensive, non-proteinuric woman.

PREGNANCY-INDUCED HYPERTENSION (PIH)

Hypertension occurring in the second half of pregnancy, confirmed on two or more occasions at least 4 hours apart, in a previously normotensive woman, and resolving within 6 weeks postpartum.

Elevated blood pressure measured on two or more occasions at least 4 hours apart in a previously normotensive woman after 20 weeks of gestation.

PREGNANCY-RELATED DEATH

Death of a woman within 42 days of pregnancy termination, irrespective of cause.

PRELABOUR PREMATURE RUPTURE OF MEMBRANES (Prelabour PROM)

Rupture of fetal membranes more than 1 hour before the onset of labour.

The spontaneous rupture of membranes at any time after the age of viability but before the onset of labour.

PREMATURE RUPTURE OF MEMBRANES (PROM)

Spontaneous rupture of fetal membranes before the onset of labour, irrespective of gestational age.

It can be:

Preterm PROM – Occurs before 37 weeks.
Pre-labour PROM – Occurs at term but before the onset of labour.

PRESENTATION

The part of the fetus that overlies the pelvic brim or occupies the lower uterine segment.

The part of the fetus occupying the lower uterine segment, as determined by abdominal palpation.

PRESENTING PART

The part of the fetus that is felt or palpated during a vaginal examination.

PRESENTING PART & DENOMINATORS

Cephalic → Occiput
Shoulder → Acromion
Breech → Sacrum
Face → Chin/Mentum

PRETERM LABOUR

The onset of spontaneous, painful uterine contractions after the age of viability but before 37 completed weeks of gestation, with associated cervical changes.

PRETERM PRELABOUR RUPTURE OF MEMBRANES (PPROM)

Occurs when the rupture of membranes happens after the age of viability (28 weeks gestational age) but before 37 weeks.

PRIMARY DYSFUNCTIONAL LABOUR

Poor progress of labour where cervical dilatation is less than 1 cm/hour in the active phase (from the onset).

PRIMARY POSTPARTUM HAEMORRHAGE (PPH)

Bleeding in excess of:

500 mL per vagina following vaginal delivery
1000 mL following caesarean section
1500 mL following caesarean hysterectomy
Blood loss capable of causing haemodynamic instability within 24 hours postpartum

PRIMIPARA

A woman who has carried a pregnancy beyond the age of viability irrespective of the outcome or route of delivery.

PROLONGED LATENT PHASE

A retrospective diagnosis of a latent phase that has not progressed to the active phase after 8 hours (up to a maximum of 24 hours).

PROLONGED PREGNANCY

A pregnancy extending beyond 42 weeks after the last menstrual period (LMP) or 40 weeks after a known date of conception.

PROLONGED PREMATURE RUPTURE OF MEMBRANES (Prolonged PROM)

Rupture of fetal membranes more than 24 hours before the onset of labour.

PUERPERAL PYREXIA

Presence of maternal fever ≥38°C after 24 hours of birth but within 10 days postpartum.

PUERPERAL SEPSIS

Infection of the genital tract occurring during labour or within 42 days postpartum, presenting with pyrexia lasting more than 10 days postpartum.

QUICKENING

The first maternal perception of fetal movement:

Primigravida: 18–20 weeks
Multigravida: 16–18 weeks

RESTITUTION

The rotation of the fetal head through 1/8th of a circle to align with the oblique position of the shoulders during vaginal delivery.

RETROPLACENTAL

Located between the placenta and the uterine wall.

SECONDARY DYSFUNCTIONAL LABOUR / SECOND ARREST

A condition where cervical dilatation, initially progressing at ≥1 cm/hour, slows or stops, typically after 7 cm, often due to cephalopelvic disproportion (CPD).

STATION

Describes the relationship of the fetal presenting part to the maternal ischial spines.

STIMULATION OF LABOUR

The artificial enhancement of uterine contractions after rupture of the fetal membranes.

SECONDARY POSTPARTUM HAEMORRHAGE (PPH)

Bleeding per vagina in excess of normal lochia after 24 hours postpartum.

SEPSIS IN THE PUERPERIUM

Infection from any cause apart from the genital tract occurring during the puerperium.

SHOCK

Persistent severe hypotension defined as systolic blood pressure <90 mmHg for more than 60 minutes and pulse rate ≥120 bpm despite aggressive fluid management.

SKILLED BIRTH ATTENDANT

An accredited health professional such as a midwife, doctor, or nurse who has been educated and trained to proficiency in managing normal pregnancies, childbirth, and the immediate postnatal period, as well as in identifying, managing, and referring women and neonates with complications.

SMALL FOR GESTATIONAL AGE (SGA)

When the estimated fetal weight is below the 10th percentile for gestational age, sex, and race.

SPURIOUS LABOUR

A retrospective diagnosis characterized by intermittent uterine contractions with no cervical changes after 24 hours.

STROKE

A neurological deficit of cerebrovascular origin that persists beyond 24 hours or is interrupted by death within 24 hours.

SUBCHORIONIC

Located between the placenta and the membranes.

SYNCLITISM

The relationship of the sagittal sutures to the plane of the pelvic inlet: to the sacrum posteriorly and the symphysis pubis anteriorly when the fetal head is in the transverse position.

TACHYSYSTOLE

More than five contractions in 10 minutes.

TERM PRELABOUR RUPTURE OF MEMBRANES (TPROM)

Rupture of membranes occurring after 37 weeks of gestation but before the onset of labour.

TERM PREGNANCY

Pregnancy between 37 completed weeks and 41 weeks + 6 days, counted from the first day of the last normal menstrual period (LNMP).

TRIAL OF LABOUR

The conduct of labour in a primigravida with a borderline pelvic size and an average-sized baby, with the hope that adequate uterine contractions will allow for sufficient pelvic expansion, leading to vaginal delivery.

TRANSIENT HYPERTENSION IN PREGNANCY

Hypertension occurring towards term or in the early puerperium, which resolves within 10 days postpartum.

UNSTABLE LIE

A condition where there is repeated change in fetal lie and presentation on at least two occasions during abdominal examination at term by the same examiner.