Anatomy and Physiology of Pregnancy Overview

Gravida

Indicates the number of times a person has been pregnant regardless of outcome.

Nulligravida

Never Pregnant

Primigravida

First time pregnant

Multigravida

Two or more times pregnant

Para

The number indicates the number of times a person has given birth, including living/stillborn and excluding abortions.

Parity

Number of pregnancies in which fetus or fetuses have reached 20 weeks of gestation

Nullipara

No completion of pregnancy >/= 20 weeks of gestation

Primapara

Completion of one pregnancy >/= 20 weeks of gestation

Multipara

Completion of two or more pregnancies >/= to 20 weeks of gestation

Grand Multi Para

Completion of >/= 5 pregnancies greater than period of viability

Viability

Capacity of fetus to live outside the uterus (22 - 25 weeks of gestation).

Preterm

20 weeks of gestation to 36 weeks + 6 days of gestation.

Late Preterm

34 weeks to 36 weeks + 6 days of gestation.

Term

37 weeks of gestation to 40 weeks + 6 days of gestation.

Early Term

37 weeks to 38 weeks + 6 days of gestation.

Full Term

39 weeks to 40 weeks + 6 days of gestation.

Late Term

41st week of gestation.

Post Term

≥ 42 weeks of gestation.

Extremely Preterm

Less than 28 weeks of gestation.

Very Preterm

28 weeks to 32 weeks of gestation.

Moderate to Late Preterm

32 to 37 weeks of gestation.

LMP

Last menstrual period

Gestational Age (GA)

LMP to current duration in pregnancy.

5-Digit Method

A method to calculate obstetrical history: G (gravidity), T (term), P (preterm), A (abortions), L (living children).

2-Digit Method

G/P= Gravidity (Number of pregnancies)/Para (Number of pregnancies carried to age of viability) - Not recommended.

Human chorionic gonadotropin (hCG)

Earliest biomarker for pregnancy; starts production on implantation day, detected 8-10 days after fertilization, peaks at 9-10 weeks of GA, stabilizes at 20 weeks GA.

Enzyme-linked immunosorbent assay (ELISA)

Most popular test for detecting pregnancy.

The results are affected by last menstrual period and a host of other factors.

Medications like anticonvulsants and tranquilizers can lead to false positives, while Diuretics and promethazine can lead to false negatives

Gestation Trophoblastic Disease

Abnormal placental (trophoblast/Chorionic villi) development with no viable fetus. Usually Benign (3% can develop into Choriocarcinoma).

Types include Hydatidiform mole and Gestational trophoblastic Neoplasia

Hydatidiform mole (Molar pregnancy)

A type of Gestation Trophoblastic Disease which can be complete or partial.

Gestational trophoblastic Neoplasia

An invasive type of Gestation Trophoblastic Disease including invasive mole, Choriocarcinoma & Placental site tumour.

Risk factors for Gestation Trophoblastic Disease

Previous history, Blood groups A/AB, Extreme reproductive age, Asians.

Signs and Symptoms of Gestation Trophoblastic Disease

Vaginal bleeding

Enlarged Uterus

Ovarian cyst/torsion

Hyperemesis Gravidarum

signs of Pre-eclampsia,

Increased hCG levels - hyperthyroidism.

Investigation for Gestation Trophoblastic Disease

Increased beta hCG level

Transvaginal U/S - 'snowstorm appearance',

Close follow-up with repeated hCG level monitoring, Chemotherapy.

Management of Gestation Trophoblastic Disease

Evacuation of uterus (ERPC) and histology,

Close follow-up with repeated monitoring of serum hCG levels

Chemotherapy

Counselling (no pregnancy for min of 3 months, not take OCT/HRT, can recur, histology with each future pregnancy, psychological well-being)

Surgery - tumor removal/Hysterectomy.

Signs of Pregnancy - Presumptive

Subjective feelings from the person, these signs can be cause by other issues in the body aside from pregnancy.

Breast Changes (3-4 weeks)

Amenorrhea (4 weeks)

Nausea/Vomiting (4-14 weeks)

Urinary Frequency (6-12 weeks)

Fatigue (12 weeks)

Quickening (16-20 weeks).

Quickening

First fetal movement feels like a flutter in the belly.

Signs of Pregnancy - Probable

Objective changes assessed by an examiner

Goodell Sign (5-6 weeks),

Chadwick's Sign (6-8 weeks),

Hegar Sign (6-12 weeks),

Osiander sign (8 weeks),

Positive pregnancy test Serum (4-12 weeks),

Positive pregnancy test urine (6-12 weeks),

Braxton Hicks (14-16 weeks),

Ballottement (16-28 weeks).

Goodell Sign (5-6 weeks)

Softening of the cervix.

Is brought about by increased vascularity, slight hypertrophy, and hyperplasia

Chadwick’s Sign (6-8 weeks)

Purplish blue appearance of the cervix

Hegar Sign (6-12 weeks)

Softening of the lower segment of the uterus (isthmus)

Osiander Sign (8 Weeks)

Feeling of pulsation in the walls of the vagina

Braxton Hicks (14-16 weeks)

Painless uterine contractions that help with circulation. Later on, it develops to false labour pains

Ballottement (16-28 weeks)

When the baby is tapped, the baby bounces on the uterine wall and then bounces back.

Signs of Pregnancy - Positive

Fetal Visualization by U/S (5-6 weeks)

Fetal heart tone using U/S (6 weeks),

Fetal Visualization using radiography (16 weeks),

Fetal heart tone using doppler U/S stethoscope (8-17 weeks),

Fetal heart tone using fetal stethoscope (17-19 weeks),

Fetal movement palpated (19-22 weeks),

Visible fetal movement (Late pregnancy).

Uterine Enlargement

Early uterine enlargement results from increased vascularity and dilation of blood vessels, hyperplasia and hypertrophy

Hen's egg - 7 weeks,

Orange - 10 weeks,

Grapefruit - 12 weeks.

After the third month, uterine enlargement is primarily the result of mechanical pressure of the growing fetus.

Shape of Uterus during Pregnancy

Upside-down pear - Conception,

Spherical - 2nd trimester,

Large/Ovoid - Later pregnancy.

Lightening

Between weeks 38 and 40, fundal height decreases as the fetus begins to descend and engage in the pelvis.

In Nullipara occurs in the last 4 weeks before labour

In Multipara it occurs at the start of labour

Height of Fundus

Factors affecting FH include:

Fetal position

Amniotic Fluid amount (Polyhydramnios, Oligohydramnios)

Number of fetus

Different examiner technique.

Reproductive system Adaptation to pregnancy

Chadwick sign

Leukorrhea

Increased progesterone/ Estrogen

Hyperplasia

Exfoliation of vaginal epithelium

Discharge

Operculum

Leukorrhea

A white or slightly grey mucoid discharge with a faint musty odour. This copious mucoid fluid occurs in response to cervical stimulation by estrogen and progesterone.

The fluid is whitish because of the presence of many exfoliated vaginal epithelial cells caused by the hyperplasia of normal pregnancy.

This vaginal discharge is never pruritic or blood stained. The mucus fills the endocervical canal, resulting in the formation of the mucous plug (operculum).

Vaginal Microbiome

The vaginal microbiome changes during pregnancy with an increase in at least four species of Lactobacillus and a decrease in anaerobic bacteria.

This results in a lower pH of vaginal secretions, ranging from about 3.5 to 6.0 (nonpregnant, 4.0 to 5.0).

Alterations in the vaginal microbiome help to prevent ascending bacterial infections of the uterus that contribute to preterm labour and birth.

Operculum

Mucoid plug

Discharged at the beginning of the labour and delivery process. Signifies the start of the process.

Breasts adaptations

Fullness, heaviness

heightened sensitivity from tingling to sharp pain

areolae become more pigmented

Montgomery's tubercles develop

Colostrum (16 weeks)

Colostrum

A form of milk produced during pregnancy, present from 16 weeks.

Cardiovascular system adaptations

Structural changes

Blood Volume

Heart Rate

Cardiac Output

Supine Hypotension Syndrome

Hypercoagulability

Varicose Veins

CV Adaptations: Structural Changes

Slight enlargement-reversed by 6 months postpartum

Diaphragm displaced upwards, elevated and shifted upwards, Apical impulse shifts laterally upward.

CV Adaptations: Blood Volume

Increases by 40-50%

CV adaptations: Heart Rate (HR) increase

The patient’s heart rate begins to increase at about 5 weeks of gestation, reaching a peak of 15 to 20 beats/minute over the prepregnancy baseline by 32 weeks and persisting until term.

This represents an increase of approximately 17% over the prepregnancy heart rate.

CV Adaptations: Cardiac output (CO) increase

Cardiac output increases from 30 to 50% during pregnancy and half of this increase occurs by 8 weeks of gestation.

A small decline occurs by term. Compared with nulliparous patients, parous patients have a significantly higher median cardiac output than that of patients with normal twin gestations, and cardiac output increases to an even greater extent from the mid-trimester of pregnancy

This elevated cardiac output is largely a result of increased stroke volume and heart rate and occurs in response to increased tissue demands for oxygen.

CV Adaptations: Blood Pressure

Increased cardiac output affects blood pressure during pregnancy.

CV Adaptations: Supine Hypotension Syndrome

Occurs when the ascending vena cava and descending aorta are compressed.

The labouring patient is at greater risk for supine hypotension if the uterus is particularly large because of multifetal pregnancy, hydramnios, or obesity or if the patient is dehydrated or hypovolemic. In addition, anxiety, pain, and some medications can cause hypotension

CV Adapations: Hypercoagulability

There is a greater tendency for blood to coagulate during pregnancy because of increases in various clotting factors

(i.e., factors VII, VIII, IX, and X, and fibrinogen) and decreases

in factors that inhibit coagulation (e.g., protein S).

This tendency, combined with the fact that fibrinolytic activity is depressed during pregnancy and the postpartum period, provides a protective function to decrease the chance of bleeding but also makes the patient more vulnerable to thrombosis, especially after Caesarean birth.

CVS Adaptations: Varicose Vein

Compression of the iliac veins and inferior vena cava by the uterus

causes increased venous pressure and reduced blood flow in the legs, except when the patient is in the lateral position.

These alterations contribute to the dependent edema, varicose veins in the legs and vulva, and hemorrhoids that may develop in the latter part of term pregnancy and can lead to increased risk for venous thromboembolism

CVS Adaptations: Physiological Anemia

Because the plasma increase is greater than the increase in RBC production, there is a decrease in normal hemoglobin and hematocrit values which leads to an anemic state

Respiratory System Adaptation

Increase in tidal volume by 40%

Increase in O2 consumption and CO2 Production by (20-30%)

Shortness of Breath

Renal System Adaptation

Increased progesterone leads to increased vascularities of afferent arterioles which leads to increased blood flow to the glomerulus, increasing GFR which leads to increased urine and size of ureters and nephrons

Increased progesterone also leads to decreased ureter motility which leads to increased urinary stagnation, increasing bacterial colonization which leads to increased risk of UTI/Nephiritis/ Blood Infection

Integumentary System adaptations

Anterior Pitituary Hormone Melanotropin causes Hyper pigmentation. Leads to:

Chloasma

Linea nigra

Striae gravidarum

Palmar Erythema

Polymorphic eruption of pregnancy/ Pruritic Urticarial Papules and Plaques of pregnancy

Chloasma

Also known as the mask of pregnancy, a skin condition characterized by a blotchy, brownish hyperpigmentation

of the skin over the cheeks, nose, and forehead, especially

in pregnant patients with dark complexions

Linea nigra

A dark line that appears on the abdomen during pregnancy.

Striae gravidarum

Stretch marks that can occur during pregnancy, often with a familial tendency.

Polymorphic eruption of pregnancy (PEP)

Also known as pruritic urticarial papules and plaques of pregnancy (PUPPP), a skin condition that can occur during pregnancy.

and is associated with increased weight gain in the pregnant patient, multiple gestations, hypertension, and induction of labour Although it can cause significant discomfort, it is not associated with adverse outcomes for the pregnant patient or fetus.

Neurological Adaptation

Carpel Tunnel Syndrome

Decreased sensation

Tension Headache

Syncope

Postural Hypotension

Carpel Tunnel Syndrome

Edema involving the peripheral nerves during the last trimester. The syndrome is characterized by paresthesia (abnormal sensation such as burning or tingling) and pain in the hand, radiating to the elbow.

The sensations are caused by edema that compresses the median nerve beneath the carpal ligament of the wrist. Smoking and alcohol consumption can impair the microcirculation and may worsen the symptoms.

Decreased sensation

Compression of nerves due to enlarging uterus.

Tension Headache

Anxiety/uncertainty.

Fainting/Syncope

Common & usually due to postural hypotension; care when getting up.

Appetite changes during pregnancy

Nausea/Vomiting (N/V), smells can trigger, subsides by end of 3rd month.

Hyperemesis Gravidarum

Excessive vomiting leading to weight loss, electrolyte imbalance, nutritional deficiency (0.3-3%).

PICA

Nonfood craving (clay, ice, detergent) that can affect nutrition.

Esophageal regurgitation

Heartburn (Pyrosis).

Constipation

Common gastrointestinal issue during pregnancy.

Hemorrhoids

Swollen veins in the rectal area that can occur during pregnancy.

Gallbladder changes in pregnancy

Increased progesterone decreases gastric motility leading to bile stagnation and cholestasis.

Signs/Symptoms of Hyperemesis Gravidarum

Protracted vomiting, retching, severe dehydration, weight loss requiring hospitalization.

Management of Hyperemesis Gravidarum

Includes small frequent diet, support, oral fluids, IV fluids, medication therapy (antiemetics, steroid, Vit B6, multivitamin), emotional support.

Human chorionic gonadotropin

A hormone produced during pregnancy.

Progesterone

A hormone that helps maintain pregnancy.

Estrogen

A hormone that plays a key role in pregnancy.

Serum prolactin

A hormone involved in lactation.

Oxytocin

A hormone that stimulates uterine contractions during labor.

Human placental lactogen

Previously called chorionic somatomammotropin, it helps regulate metabolism during pregnancy.

Thyroxine-binding globulin

A protein that binds thyroid hormones.

Thyroxine

A hormone produced by the thyroid gland.

Triiodothyronine

Another hormone produced by the thyroid gland.

Parathyroid

Glands that regulate calcium levels in the body.

Insulin

A hormone that regulates blood sugar levels.

Cortisol

A hormone that helps manage stress and metabolism.

Aldosterone

A hormone that regulates sodium and potassium levels.