Pregnancy begins with the fertilization of the ovum and its subsequent implantation into the uterine wall. The duration of pregnancy is counted in weeks of gestation from the first day of the last menstrual period and on average lasts 40 weeks. Presumptive signs of pregnancy include amenorrhea, nausea and vomiting, and breast enlargement and tenderness. Preconception counseling assists in the planning of pregnancy through education and risk assessment to help ensure best possible outcomes. Pregnancy can be confirmed definitively via positive serum or urine hCG tests and detection of the embryo on ultrasound. Ultrasound is also used to determine the gestational age and date of delivery. Women experience several physiological changes during pregnancy (e.g., increased plasma volume, venous stasis, increased insulin secretion, increased oxygen demand), which can lead to symptoms and conditions that may require treatment (e.g., peripheral edema, insulin resistance, hypercoagulability, dyspnea). Regular check-ups should be performed to detect potential high-risk pregnancies as well as fetal and maternal complications.
See also “” and “ .”
Gravidity: the number of times a woman has been pregnant, regardless of pregnancy outcome
- Nulligravidity: no history of pregnancy
- Primigravidity: history of one pregnancy
- Multigravidity: history of two or more pregnancies
Parity: the number of pregnancies that reached beyond 20 weeks' gestation or terminated with the birth of an infant weighing > 500 g
- Nulliparity: absence of pregnancies that reached beyond 20 weeks' gestation or birth of an infant weighing > 500 g
- Primiparity: a history of one pregnancy that reached beyond 20 weeks' gestation or birth of an infant weighing > 500 g
- Multiparity: a history of more than one pregnancy that reached beyond 20 weeks' gestation or birth of an infant weighing > 500 g
Fetal age 
- Counted as completed weeks of gestation and completed days (0–6) of the current week of pregnancy
- Gestational age: estimated fetal age (in weeks and days) calculated from the first day of the last menstrual period
- Conceptional age: the age (in weeks and days) of the fetus calculated from the day of conception (fertilization)
- Duration of pregnancy
Trimesters of pregnancy
- First trimester (weeks 1–13)
- Second trimester (weeks 14–26)
- Third trimester (weeks 27–40)
|TPAL||Obstetric recording system that comprises: term births (T), premature births (P), abortions (A), and living children (L)||A woman who reports 5 pregnancies with two miscarriages at weeks 11 and 14 of pregnancy, one medical abortion, one delivery at week 39 of pregnancy of a child weighing 3100 g, one delivery at week 29 of pregnancy of a child weighing 2100 g who died soon after birth should be reported as: T1, P1, A3, L1.|
|GTPAL||An extension of the TPAL recording system that also includes gravidity (G)||A woman who reports 5 pregnancies with two miscarriages at weeks 11 and 14 of pregnancy, one medical abortion, one delivery at week 39 of pregnancy of a child weighing 3100 g, one delivery at week 29 of pregnancy of a child weighing 2100 g who died soon after birth should be reported as: G5, T1, P1, A3, L1.|
|GP||Obstetric recording system that comprises: gravidities (G) and parities (P)||A woman who reports 4 pregnancies and one delivery of an infant weighing 2100 g at week 32 of pregnancy is reported as: G4, P1.|
Stages of pregnancy
Trimesters of pregnancy
- First trimester (week 1–13)
- Second trimester (week 14–26)
- Third trimester (week 27–40)
Stages of pregnancy
|Day 0|| |
|Days 6–14|| |
|Week 3|| || |
|From week 9|| |
The earlier disruptions take place during fetal development, the more complicated the resulting congenital anomalies!
- Fertile women of reproductive age should be asked about their intention to become pregnant by their healthcare provider (all those planning to become pregnant should receive counseling).
Preconception counseling aims to:
- Identify and address any modifiable factors that may negatively affect pregnancy and childbirth.
- Educate women and men about options for risk reduction and elimination.
Patient medical history
Medical conditions: review history and identify chronic medical conditions that may affect pregnancy (e.g., hypothyroidism, diabetes mellitus, chronic hypertension)
- Diabetes mellitus
- Family history of inherited conditions: assess family history of genetic conditions and cancer (e.g., breast cancer, endometrial cancer, colon cancer) and refer couples with a positive history for counseling.
- Communicable diseases
- Review current medications, including alternative medicine preparations (e.g., herbal medicine, naturopathy) and nutritional supplements.
- Discontinue and switch to safer medications, if possible.
- Adjust the regimen of necessary medications and consider using the lowest dose possible for potentially harmful agents.
- Measles, mumps, rubella (), and
- Influenza: Women who wish to conceive should receive the annual .
- Tetanus, diphtheria, and pertussis (Tdap vaccine): Women who wish to conceive should receive the Tdap vaccine according to the guidelines.
- Hepatitis B vaccine: Vaccinate women with high risk for hepatitis B.
- Review history of psychiatric disorders.
- Inform about the risks of medication during pregnancy.
- Screen women with no history of mental health conditions for anxiety and depression.
- Recommend maintaining a normal body weight prior to conception.
- Encourage regular moderate-intensity exercise.
- Screen for sufficient intake of macronutrients and micronutrients (calcium, iron, vitamin B12, vitamin B, vitamin D).
- Ensure vitamin A is not taken in excess
- Recommend intake of 0.4 mg of folic acid daily, ideally 4 weeks prior to conception, and continue for at least the first 2–3 months of pregnancy.
- Substance use
- Screen all women for alcohol, tobacco, and recreational drug use.
- Educate about associated adverse effects of substance use on maternal and fetal pregnancy outcomes.
- Provide assistance and/or refer to the proper specialists for tobacco, alcohol, and recreational drug use cessation.
Management of exposures 
- Exposure to harmful agents
- Advise patients to assess workplace and household for potentially harmful agents (e.g., heavy metals, solvents, chemicals).
- Educate the patient about the avoidance of harmful agents and refer them to occupational medicine programs as needed.
- Exposure to violence
- Screen for family violence at each visit.
- If ongoing abuse is identified, providers should:
- Provide community resources to the patient
- Report the case as appropriate
- Presumptive signs
|Probable signs |
|Signs||Physical findings||Weeks of pregnancy|
|Goodell||Cervical softening||First 4 weeks|
|Hegar||Softening of the lower segment of the uterus||Between 6–8 weeks|
|Ladin||Softening of the midline of the uterus||First 6 weeks|
|Chadwick||Bluish discoloration of vagina and cervix||Between 6–8 weeks|
|Telangiectasias and palmar erythema||Small blood vessels and redness of the palms||First 4 weeks|
|Chloasma||Hyperpigmentation of the face (forehead, cheeks, nose)||First 16 weeks|
Human chorionic gonadotropin (hCG)
- Site of production: placental syncytiotrophoblast
- Pregnancy test: measurement of human chorionic gonadotropin (β-hCG)
Ultrasound findings in normal pregnancy (abdominal or transvaginal)
- Confirms pregnancy
- At 5–6 weeks of pregnancy: detection of the embryo and cardiac activity
- At 10–12 weeks of pregnancy: detection of fetal heartbeat with doppler ultrasound
- At 18–20 weeks of pregnancy: fetal movements
|Transvaginal ultrasound findings |
in normal pregnancy
|Gestational age ||β-hCG mlU/mL|
Gestational age and estimated date of delivery
- Naegele rule: used to calculate the date of delivery (due date)
Symphysis fundal height: the length from the top of the uterus to the top of the pubic symphysis
- Used to assess fetal growth and development from approx. 20 weeks' gestation onwards
- Development is approx. 1 cm/week after 20 weeks
- Correlates with gestational age
Cardiovascular system 
- ↑ Progesterone → ↓ vascular tone → ↓ peripheral vascular resistance (↓ afterload)
- Innocent systolic murmur
- The apex beat is displaced upward.
- Varicosity and edema of lower limbs
- Aggravation of preexisting valvular diseases
Respiratory system 
- ↑ Oxygen consumption (by approx. 20%)
- ↑ Intraabdominal pressure through uterine growth → dyspnea (the diaphragm is displaced upwards → ↓ total lung capacity, residual volume, functional residual capacity, and expiratory reserve volume)
- Progesterone stimulates the respiratory centers in the brain → hyperventilation (to eliminate fetal CO2 more efficiently) → physiological, chronic compensated respiratory alkalosis
Renal system 
- ↑ GFR → ↓ BUN and creatinine
- ↑ Aldosterone → ↑ plasma volume and hypernatremia
- ↑ Glucose levels in urine (increased glomerular filtration results in overload of the glucose carrier responsible for its resorption)
- ↑ Urinary frequency
Endocrine system 
- Human placental lactogen: a hormone synthesized by syncytiotrophoblasts of the placenta, which promotes the production of insulin-like growth factors.
- Thyroid hormones
- ↑ Triglycerides and cholesterol (due to increased lipolysis and fat utilization)
- Hyperplasia of lactotroph cells in the anterior pituitary; → physiological enlargement of the pituitary gland (up to 40% increase from pregestational volume)
Hematologic system 
- ↑ Plasma volume → ↓ hematocrit, especially towards the end of pregnancy (30–34th week of gestation) → dilutional anemia (hemoglobin value rarely drops below 11 g/dL)
- ↑ RBC count (increases from 8–10th week of gestation until the end of pregnancy)
- ↓ Platelet count 
- ↑ WBC count
- ↓ Albumin
- Hypercoagulability is due to an increase in fibrinogen, factor VII, and factor VIII and a decrease in protein S (reduces the risk of intrapartum blood loss).
- ↑ Alkaline phosphatase (placental isoenzyme)
Gastrointestinal system 
- Increased pressure from the uterus, lumbar lordosis, and relaxation of the ligaments supporting the joints of the pelvic girdle can cause lower back pain.
- Spider angioma
- Palmar erythema
- Striae gravidarum: scarring that manifests as erythematous, violaceous, and/or hypopigmented linear striations on the abdomen.
- Hyperpigmentation: chloasma, linea nigra, hyperpigmentation of the nipples
- Uterus: increase in size
- Vulva and vagina
- Mammary glands increase in size
- Nutritional intake: must be adapted to meet the demands of both the mother and the fetus
- Limit caffeine intake: daily recommended dose < 200 mg (this equals about 1–2 cups of coffee or 2–4 cups of caffeinated tea)
- Avoid alcohol and tobacco use throughout pregnancy. 
- Avoid unwashed or uncooked foods.
- Fish (contamination with parasites and bacteria)
- Milk products: high risk of
- Meat: high risk of
- Avoid fish with possibly high levels of methylmercury, esp. tilefish, swordfish, shark, mackerel, and tuna.
|Recommended vitamin and mineral supplementation in pregnancy |
|Supplementation||Reason for increased demand||Consequences of deficiency|
|Folic acid || |
|Vitamin B12|| || || |
|Iron || || |
|Calcium || || |
|Iodine || || || |
Recommended weight-gain during pregnancy 
- Recommended weight-gain is determined by BMI prior to pregnancy
- Average recommended daily calorie intake
- Regular physical activity is recommended (see below).
- Regular physical activity (e.g., aerobic and strength-training exercise) is considered beneficial and is recommended before, during, and after pregnancy.
- Careful evaluation of medical and obstetric disorders is necessary before recommending regular physical activity.
- Exercise routines that are considered unsafe during pregnancy should be avoided or modified accordingly.
|Safe and unsafe sports during pregnancy |
|Safe activities|| |
Physical activity should be discontinued in the event of the following: antepartum or postpartum hemorrhage, uterine contractions, amniotic fluid leakage, chest pain, dyspnea before exertion, dizziness, headaches, calf pain/swelling, and/or muscle weakness with impaired balance.
Early identification of high-risk pregnancies is vital in order to prevent the occurrence of maternal and fetal complications. They require regular prenatal care to monitor and support the pregnant mother (see “ ”).
Risk factors for a complicated pregnancy 
- Family history (medical and obstetric) of complicated pregnancies
- Personal history
- Advanced maternal age (> 35 years)
- First pregnancy
- Multiparity (> 5 births)
- Medical conditions (e.g., epilepsy, malignancies) , , ,
- Social and environmental factors (e.g., drug use, stress)
- Preexisting gynecological conditions (e.g., uterine leiomyoma, history of uterine surgery)
- Prior complicated pregnancies
- Complications that arise during pregnancy: See “ ” and section below.
- Definition: amount of amniotic fluid is less than expected for gestational age
- Small abdominal girth and uterine size for gestational age
- Ultrasound: determine amniotic fluid and assess for fetal anomalies
Amniotic fluid index (AFI): a semiquantitative tool used to assess amniotic fluid volume (normal range: 8–18 cm)
- Determined by dividing the uterus into 4 quadrants, holding the transducer perpendicular to the patient's spine, and adding up the deepest vertical pocket of fluid in each quadrant.
- Oligohydramnios: < 5
- In pregnancies < 24 weeks and multiple gestations, the single deepest pocket is used (normal range: 2–8 cm).
- Intrauterine growth restriction (due to diminished mobility of the fetus)
- Birth complications (e.g., umbilical cord compression)
Potter sequence: oligohydramnios → intrauterine compression and decreased amniotic fluid ingestions → decreased space for fetal development → internal and external deformations
- Fetal bilateral renal agenesis (classical cause) → oligohydramnios
- Pulmonary hypoplasia (cause of death due to severe neonatal respiratory insufficiency)
- Craniofacial abnormalities (e.g., prominent epicanthal folds, flattened nose, receding chin, low set ears)
- Wrinkling of the skin
- Limb anomalies (e.g., bowed legs, clubbed feet)
Potter babies cannot Pee.
- Definition: excessive amniotic fluid volume expected for gestational age that results in uterine distention.
- Typically idiopathic (∼ 70% of cases) 
- Gastrointestinal (e.g., : , )reduced swallowing and absorption of amniotic fluid
- CNS: ; (leads to impaired swallowing of amniotic fluid, leakage of cerebrospinal fluid, and increased urination due to lack of fetal ADH), (due to leakage of cerebrospinal fluid) 
- Pulmonary: cystic lung malformations
- Multiple pregnancy: twin-to-twin transfusion syndrome
- Fetal anemia 
- Intrauterine infections (e.g., )
- Maternal conditions
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